ARTICLE | doi:10.20944/preprints202002.0069.v1
Subject: Mathematics & Computer Science, Applied Mathematics Keywords: coal; supercritical CO2; Gaussian process regression; machine learning; adsorption model
Online: 5 February 2020 (14:09:33 CET)
Deep coal beds have been suggested as possible usable underground geological locations for carbon dioxide storage. Furthermore, injecting carbon dioxide into coal beds can improve the methane recovery. Due to importance of this issue, a novel investigation has been done on adsorption of carbon dioxide on various types of coal seam. This study has proposed four types of Gaussian Process Regression (GPR) approaches with different kernel functions to estimate excess adsorption of carbon dioxide in terms of temperature, pressure and composition of coal seams. The comparison of GPR outputs and actual excess adsorption expresses that proposed models have interesting accuracy and also the Exponential GPR approach has better performance than other ones. For this structure, R2=1, MRE=0.01542, MSE=0, RMSE=0.00019 and STD=0.00014 have been determined. Additionally, the impacts of effective parameters on excess adsorption capacity have been studied for the first time in literature. According to these results, the present work has valuable and useful tools for petroleum and chemical engineers who dealing with enhancement of recovery and environment protection.
ARTICLE | doi:10.20944/preprints202011.0500.v1
Subject: Engineering, Automotive Engineering Keywords: water vapour; bound water; diffusion; adsorption; wood; sorption experiment
Online: 19 November 2020 (10:34:08 CET)
The paper presents a model of moisture transport in wood taking into account diffusion and the accompanying adsorption of water vapour through the skeleton. A two-parameter form of the source term was proposed, depending on the distance of the current mass concentration of bound water from the equilibrium state. The tests on cubic samples with a side of 2 cm were carried out which allowed to determine the coefficients of the proposed model on the basis of the reverse method. The tests were performed for pine, larch, oak and ash in all directions of orthotropy. Also the tests on thin samples were performed to verify the source term.
ARTICLE | doi:10.20944/preprints201903.0274.v1
Subject: Engineering, General Engineering Keywords: adsorption kinetics; isotherm models; Jatropha curcas; Congo red; effects
Online: 29 March 2019 (08:09:08 CET)
The Batch process of Adsorption were conducted using Congo red (CR) as the adsorbate and Jatropha curcas seed (chaff) as the adsorbent material. Adsorption kinetics and isotherms analysis were conducted and results obtained confirmed the adsorption process as highly dependent on effects such as; contact time, adsorbent dosage, initial dye concentration and the particle sizes of adsorbate. However, the sorption equilibrium for Congo red dye unto jatropha curcas seed (chaff) was reached within 180 minutes, more so, the Adsorption efficiency was recorded at 82.05%. The process of the experimental sorption kinetics followed a pseudo-second-order kinetic model while Freundlich isotherm model was best applicable for obtaining the equilibrium of the parameters. These is an effective confirmation and validation of jatropha curcas seed (chaff) application as environmentally friendly and low-cost biomaterial for dye removal from aqueous solutions and industrial effluents.
ARTICLE | doi:10.20944/preprints201807.0489.v1
Subject: Chemistry, Physical Chemistry Keywords: CO2 adsorption, CH4 adsorption, biomass, activated carbon.
Online: 25 July 2018 (15:29:22 CEST)
The aim of the present study is to provide new insights into the CO2 and CH4 adsorption using a set of biomass-based activated carbons obtained by physical and chemical activation of olive-stones. The adsorption behavior is analyzed by means of pure gas adsorption isotherms up to 3.2 MPa at two temperatures (303.15 and 323.15 K).The influence of the activation method on the adsorption uptake is studied in terms of both textural properties and surface chemistry. For three activated carbons the CO2 adsorption was more important than that of CH4. The chemically activation resulted in higher BET surface area and micropore volume that lead to higher adsorption for both CO2 and CH4. For methane the presence of mesopores seems to facilitate the access of the gas molecules into the micropores while for carbon dioxide, the presence of oxygen groups enhanced the adsorption capacity.
ARTICLE | doi:10.20944/preprints201806.0294.v1
Subject: Chemistry, Organic Chemistry Keywords: microporous organic polymers; nitrogen-rich; CO2 adsorption; H2 adsorption; I2 vapor sorption
Online: 19 June 2018 (10:53:12 CEST)
Microporous organic polymers (MOPs) are promising materials for gas sorption because of the intrinsic and permanent porosity, designable framework and low density. The introduction of nitrogen-rich building block in MOPs will greatly enhance the gas sorption capacity. Here, we report the synthesis of MOPs from the 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine unit and aromatic azides linkers via click polymerization reaction. FTIR and solid state 13C CP-MAS NMR confirm the formation of the polymers. CMOP-1 and CMOP-2 exhibit microporous networks with BET surface area of 431 and 406 m2 g-1 and narrow pore size distribution under 1.2 nm. Gas sorption isotherms including CO2 and H2 were measured. CMOP-1 stores superior CO2 level of 8.2 wt% (1.88 mmol g-1) at 273 K/1.0 bar and H2 uptake up to 0.6 wt% at 77 K/1.0 bar, while CMOP-2 with smaller surface area shows lower CO2 adsorption capacity of 7.3 wt% (1.66 mmol g-1) and H2 uptake (0.5 wt%). In addition, I2 vapor adsorption was tested at 353 K. CMOP-1 shows higher gravimetric load of 160 wt%. Despite of the moderate surface area, the CMOPs display excellent sorption ability for CO2 and I2 due to the nitrogen-rich content in the polymers.
ARTICLE | doi:10.20944/preprints202211.0492.v1
Subject: Materials Science, General Materials Science Keywords: calixcrown; carrier; cesium; adsorption; comparision
Online: 28 November 2022 (04:19:27 CET)
The adsorption of supramolecular composites for Cs(I) in high level liquid waste (HLLW) are different due to different carriers. We chose 25,27-bis(ethyl)-calixarene-26,28-crown-6 (ECC6) as adsorbent, SiO2-P, XAD-7 and UiO-66 as carriers. The synthesis and characterization of supramolecular ECC6 loaded with three different carriers were presented. SEM, N2 adsorption/desorption isotherms, TG-DSC spectra, FT-IR spectra results shown that ECC6 was successfully introduced into the pores of carriers via physical intermolecular interactions. ECC6/SiO2-P, ECC6/XAD-7 and ECC6/UiO-66 shown high efficiency, high selectivity towards Cs(I) over 18 typical fission or corrosion products in HNO3 solution. The adsorption properties of the three materials were investigated after electron irradiation. These results demonstrate that ECC6/SiO2-P possess greater potential for highly efficient removal of Cs(I) from HLLW.
ARTICLE | doi:10.20944/preprints202208.0049.v1
Online: 2 August 2022 (08:18:40 CEST)
CoFe2O4 is a promissing catalytic material for many chemical reactions. We have used ab initio molecular dynamic simulations to study the structure and reactivity of the A- and B-terminations of the low index CoFe2O4 (001) surfaces to water adsorption at room temperature. Upon adsorption, water partly dissociates on both termination with a higher dissociation degree on the A- termination (30% versus 19%). The 2-fold coordinated Fe3+(tet) in the tetrahedral voids and the 5-fold coordinated Fe3+(oct) in the octahedral voids are the main active sites for water dissociation on the A- and B-termination, respectively. Molecular water, hydroxydes and surface OH resulting from proton transfer to surface oxygens are present on the surfaces. Both water free sur- face terminations undergo reconstruction. The outermost Fe3+(tet) on the A-termination and B-termination move towards the nearby unoccupied octahedral voids. In the presence of a thin film of 32 water molecules, the reconstructions are partially and completely lifted on the A- and B-termination, respectively.
ARTICLE | doi:10.20944/preprints202105.0003.v1
Subject: Materials Science, Biomaterials Keywords: Palladium; Chitin; Crosslinking; Adsorption; Reusability
Online: 3 May 2021 (09:10:22 CEST)
This study reports the recovery of Pd(II) from acid solution by a polyethylenimine (PEI) crosslinked chitin (PEI-chitin) biosorbent. FE-SEM analysis demonstrated that there are many slot-like pores on PEI-chitin. N2 adsorption-desorption experiment revealed that the average pore size was 47.12 nm. Elemental analysis verified the successful crosslinking of PEI with raw chitin. The Langmuir model better explained the isotherm experimental data and the theoretical maximum Pd(II) uptake was 59.6 mg/g. The adsorption kinetic data was better described by pseudo-second-order model and the adsorption equilibrium was achieved within 30 min for all initial Pd(II) concentrations of 50-200 mg/L. In the fixed-bed column, the adsorption of Pd(II) on PEI-chitin showed slow breakthrough and fast saturation performance. The desorption experiments achieved a concentration factor of 8.4 ± 0.4. In addition, adsorption-desorption cycles in the fixed-bed column were performed up to 3 times, consequently confirming the good reusability of PEI-chitin for Pd(II) recovery. Therefore, the PEI-chitin can be used as a promising biosorbent for the recovery of Pd(II) in practical applications.
Online: 21 July 2020 (13:40:39 CEST)
Commercially available oxidized (carboxylic groups) and non-oxidized multiwalled carbon nanotubes were studied as adsorbents of cerium(III) in batch operation mode. Several variables affecting the rare earth adsorption were investigated, including: the stirring speed applied to the system, the pH of the solution and the metal concentration and carbon dosages. Although the removal of cerium from the solution is different and dependent upon the adsorbent type: i) adsorption in non-oxidized multiwalled carbon nanotubes, ii) cation exchange in the case of using oxidized multiwalled carbon nanotubes, the adsorption kinetics, the rate law and the isotherm models are the same for both adsorbents: pseudo-second order, film diffusion and Langmuir Type-1, respectively. Cerium is desorbed from loaded adsorbents using acidic solutions.
ARTICLE | doi:10.20944/preprints201911.0203.v1
Online: 17 November 2019 (13:17:04 CET)
The present investigation deals with the adsorption of chromium(III) from alkaline media using multi-walled carbon nanotubes. The adsorption of Cr(III) has been studied under various experimental conditions: stirring speed of the aqueous solution, initial metal and adsorbent concentrations, NaOH concentration in the aqueous solution, and temperature. The rate law indicated that chromium adsorption is well represented by the particle diffusion model, whereas the adsorption process fits to the pseudo-second order kinetic model within an exothermic character. Equilibrium data fit to the Langmuir type-2 equilibrium isotherm in an spontaneous process. Chromium(III) can be eluted from metal-loaded nanotubes using acidic solutions, from which fine chromium(III) oxide pigment can be ultimately yielded.
REVIEW | doi:10.20944/preprints202212.0192.v1
Subject: Chemistry, Applied Chemistry Keywords: aerogels; environmental remediation; uranium adsorption; environmental water decontamination; adsorption thermodynamics and kinetics; extraordinary adsorption capacity; qmax values; competitive ions; material recycling; uranium recovery
Online: 12 December 2022 (04:06:36 CET)
Aerogel-based adsorbents present extraordinary sorption capacity for hexavalent uranium that can be as high as 8.8 mol kg–1 (2088 g kg–1). The adsorption data follow generally the Langmuir isotherm model and the kinetic data are better described by the pseudo-second-order kinetic model, which is associated with chemisorption. Evaluation of the thermodynamic data reveals that the adsorption is generally an endothermic, entropy-driven process (ΔHo, ΔSo > 0). Spectroscopic studies (e.g., FTIR, XPS) indicate that the adsorption is based on the formation of in-ner-sphere complexes between surface active moieties and the uranyl cation. Regeneration and uranium recovery by acidification and complexation using carbonate or chelating ligands (e.g., EDTA) have been found to be successful. The application of aerogel-based adsorbents to uranium removal from industrial processes and uranium-contaminated waste waters was also successful, assuming that these materials could be very attractive as adsorbents in water treatment and uranium recovery technologies. However, the selectivity of the studied materials towards hexavalent uranium is limited suggesting further development of aerogel materials which could be modified by surface derivatization with chelating agents (e.g., salophen, iminodiacetate) presenting high selectivity for uranyl moieties.
ARTICLE | doi:10.20944/preprints202208.0510.v1
Online: 30 August 2022 (06:00:56 CEST)
The occurrence of potential spikes in a cell is a sign of life, and it is called action potential. There is a common notion that neuron signal conduction is the conduction of action potential. Hence, action potential is a typical and essential life activity. However, such potential spikes occur even in simple nonliving systems. According to the experimental observations by Pollack, structured water molecules can generate a negative potential environment. From this observation, the potential spike generation process for both living and nonliving systems caused by ion and water molecule adsorption-desorption process could be explained in this paper. So, taking into consideration the electrically neutral water molecules,the action potential generation mechanism could be explained. It is a fully inanimate model. Hence, the action potential may not be a life activity. Here, the role of water molecules in life is investigated further. It was found that the phase transition of the membrane is involved in the neuron signal conduction, but the membrane phase transition could be due to the change of state of the water molecules, which forms a large-scale structure in the cavities created by a number of lipids.
REVIEW | doi:10.20944/preprints202108.0449.v1
Subject: Chemistry, Organic Chemistry Keywords: Biosorption; Citrus aurantifolia; characteristics; adsorption isotherm
Online: 23 August 2021 (14:10:36 CEST)
Heavy metal pollution in the aquatic water bodies via the discharge of various toxic heavy metals from industrial effluents has been a major concern in the present era. Various physical and chemical processes are available to solve this problem of heavy metal pollution. Biosorption is considered as a potential alternative for the removal of heavy metals from waste waters as compared to other conventional processes. In the present work, biosorption of Cu(II), Cr(VI), Pb(II) and Zn(II) ions from aqueous solutions was carried out by using peels of Citrus aurantifolia. The peels were found to be efficient in the biosorption of all four metal ions under study. The biosorption process was found to be influenced by factors like contact time, temperature, pH, turbidity as well as biosorbent dose. Further, the change in characteristics of Citrus aurantifolia after biosorption process was studied by using E-SEM, EDAX and FT-IR analysis. The adsorption isotherm studies revealed that Freundlich isotherm model showed better fir to experimental data as compared to Langmuir isotherm model. The results were found to be significant statistically. The regeneration of biosorbent was carried out by desorption study by using certain eluents.
REVIEW | doi:10.20944/preprints202105.0599.v1
Subject: Chemistry, Analytical Chemistry Keywords: organic dyes; adsorption; removal; wastewaters; environment
Online: 25 May 2021 (10:14:49 CEST)
Even in the first quarter of XXI century, the presence of organic dyes in wastewaters is a normal occurrence in a series of countries, and being these compounds toxics, their removal from these waters is of a necessity. Among the separation technologies, adsorption processing appeared as one of the most widely used to reach this goal. The present work reviewed the most recent approaches (first half of 2021 year) about the use of a variety of adsorbents on the removal of, also, a variety of organic dyes of different nature.
ARTICLE | doi:10.20944/preprints202012.0458.v2
Subject: Engineering, Biomedical & Chemical Engineering Keywords: ammonium; adsorption; sewage sludge; kinetic; isotherm
Online: 24 December 2020 (13:50:11 CET)
Sewage sludge was utilized into biochar using the slow pyrolysis method. The biochar was then being used for ammonium removal. The sewage sludge biochar was produced at temperature of 550°C, 600°C, 650°C, 700°C and 750°C. A few characterization tests were carried out to study about the physical and chemical properties of the biochar. For instance, moisture and ash content analysis, FTIR spectroscopy, pH Zero Point Charge, biochar yield and SEM. As the pyrolysis temperature increased, the moisture content of SSB decreased while the ash content increased. The FTIR spectra of sewage sludge biochar showed that there were various organic functional groups on the surface of the biochar which were responsible for ammonium adsorption. Furthermore, through pH Zero Point Charge analysis, pH 7.0 was the most optimum pH for the adsorption test of ammonium. The optimum adsorbent dosage was 0.01g while optimum contact time was 150 minutes. Furthermore, 1.2ppm was the most optimum concentration for adsorption process. Based on the result of the characterization tests, SSB700 was the most effective biochar for ammonium adsorption. Based on the result of kinetic and isotherm analysis, the adsorption of ammonium ions usign sewage sludge biochar was a monolayer chemisorption process.
ARTICLE | doi:10.20944/preprints202005.0302.v1
Subject: Chemistry, Applied Chemistry Keywords: lanthanum; multiwalled carbon nanotubes; adsorption; recovery
Online: 18 May 2020 (12:35:28 CEST)
The behaviour of oxidized and non-oxidized multiwalled carbon nanotubes in the adsorption of lanthanum(III) from aqueous solutions is described. Metal uptake is studied as a function of several variables such as the stirring speed of the system, pH of the aqueous solution and metal and nanomaterial concentrations. The experimental results are fitted to various kinetics and isotherm models, being the rate law fitted to the film diffusion and particle diffusion models, when the non-oxidized and the oxidized nanomaterials are used to remove lanthanum from the solution, respectively. Sulphuric acid solutions seem to be appropriate to recover the metal from La-loaded nanomaterials.
REVIEW | doi:10.20944/preprints202003.0032.v1
Subject: Earth Sciences, Environmental Sciences Keywords: mercury(II); adsorption; processing; liquid effluents
Online: 3 March 2020 (02:17:56 CET)
Mercury is a toxic metal, thus, it is an element which has more and more restrictions in its uses, but despite the above, the removal of this metal, from whatever the form in which it is encountered (zero valent metal, inorganic or organic compounds), and from different sources, is of a widespread interest. In the case of Hg(II), or Hg2+, the investigations about the treatment of Hg(II)-bearing liquid effluents (real or in most cases synthetic solutions) appear not to end, and from the various separation technologies, adsorption is the most popular among researchers. In this topic, and in the 2019 year, more than 100 publications had been devote to this field: Hg(II)-removal-adsorption. This work examined all of them.
ARTICLE | doi:10.20944/preprints201909.0185.v1
Subject: Materials Science, Metallurgy Keywords: activated carbon; adsorption; copper; winemaking wastes
Online: 17 September 2019 (11:44:45 CEST)
This article presents the copper ions adsorption process using an activated carbon from winemaking wastes. The pH, temperature, activated carbon amount and initial copper concentration were varied based on a full factorial 2k experimental design. Kinetic and thermodynamic studies were also carried out. The adsorption kinetics was found follow a pseudo-second-order model. The adsorption data fit better to the Langmuir isotherm. The ANOVA demonstrated that both pH of the solution and activated carbon dosage had the greatest influence on copper adsorption. The activation energy was -32 kJ·mol-1 suggesting that the copper adsorption is a physic-sorption process. The best fit to a linear correlation was the moving boundary equation that controls the kinetics for the adsorption copper ions onto the activated carbon. The X-ray photoelectron spectroscopy (XPS) results reveal the existence of different copper species (Cu2+, Cu+ and or Cu0) on the surface of the carbonaceous adsorbent after the adsorption, which could suggest a simultaneous reduction process.
ARTICLE | doi:10.20944/preprints201810.0730.v1
Online: 30 October 2018 (20:35:07 CET)
The BIOTON® biochar, produced by a wood biomass pyrolysis process, usually applied as a soil amendment, was investigated for a novel application, i.e. the adsorption of lead from contaminated solutions. The experimental activity firstly included the physical-chemical characterization of BIOTON®; SEM images were also obtained to highlight its internal structure. The adsorption process was investigated through batch and column experiments. Adsorption kinetics showed a very rapid achievement of the equilibrium conditions, i.e. at 2h and 4h for 50 mg/L and 100 mg/L initial Pb concentration, respectively. Complete removal also occurred within the same time. The Brunauer–Emmett–Teller model better fitted the equilibrium data for both Pb concentrations, whereas the kinetics were best represented by the pseudo second order model. The column tests showed that the addition of biochar as adsorbent media within the bed significantly extended the time of breakthrough and exhaustion, with respect to the column filled with soil only. The adsorption capacities of BIOTON® versus lead solutions was found to be comparable to that reported for commercial adsorbents. Therefore, BIOTON® can be considered a valid option, with the additional benefit to reduce the environmental impact since allows to recover a residue which alternately would need to be disposed of.
ARTICLE | doi:10.20944/preprints201807.0108.v1
Subject: Materials Science, Nanotechnology Keywords: Zein; nanocomposite membrane; adsorption; wastewater; RB19
Online: 6 July 2018 (08:01:59 CEST)
The present work demonstrates the new nanofiber mats prepared through co-electrospinning of two different polymers i.e. corn protein namely Zein and Nylon-6. The composite nanofiber membrane was used as an effective adsorbent material for the removal of toxic reactive dye i.e. Reactive Blue 19 (RB 19) from water solution. These co-electrospun nanofibers had good mechanical strength compared to zein nanofibers alone. Experimental results suggested that zein/nylon nanofibers have greater potential for total removal of RB19 at room temperature within 10 min of contact time from aqueous solution. The maximum capacity was found to be 70 mg/g of nanofibers. The mechanism of RB19 removal on proposed nanofibers is mainly through hydrogen bond and electrostatic means.
ARTICLE | doi:10.20944/preprints201801.0084.v1
Subject: Earth Sciences, Geochemistry & Petrology Keywords: antimony; ferrihydrite; silica; adsorption; co-precipitation
Online: 10 January 2018 (07:02:42 CET)
Elevated antimony concentrations in aqueous environments from anthropogenic sources is becoming of global concern, here iron oxides are known to strongly adsorb aqueous antimony species with different oxidation states, but the effect of silica on the removal characteristics is not well understood despite being a common component in the environment. In this study, ferrihydrite was synthesized at various Si/Fe molar ratios to investigate its adsorption and co-precipitation behaviors with aqueous antimony anionic species, Sb(III) and Sb(V). The XRD analyses of the precipitates showed two broad diffraction features at approximately 35° and 62° 2θ, which are characteristic of 2-line ferrihydrite, no significant shifts in peak positions in the ferrihydrite regardless of the Si/Fe ratios. The infrared spectra showed a sharp band at ~990 cm−1, corresponding to asymmetric stretching vibrations of Si-O-Fe bonds which increased in intensity with increasing Si/Fe molar ratios. Further, the surface charge on the precipitates became more negative with increasing Si/Fe molar ratios. The adsorption experiments indicated that Sb(V) was preferentially adsorbed at acidic conditions and decreased dramatically with increasing pH while the adsorption rate of Sb(III) ions was independent of pH, however, the presence of silica suppressed the adsorption of both Sb(III) and Sb(V) ions. The results showed that Sb(III) and Sb(V) ions were significantly inhibited by co-precipitation with ferrihydrite even in the presence of silica by isomorphous substitution in the ferrihydrite crystal structure.
ARTICLE | doi:10.20944/preprints202301.0464.v1
Subject: Biology, Forestry Keywords: Adsorption water movement; adsorption hypothesis; plant long-distance water transport; thermodynamic water movement; not-hydraulic movement
Online: 26 January 2023 (03:02:38 CET)
Ad- and desorption forces move water in living xylem/wood from the root to the leaf thermodynamically. The doctrine of plant water transport, the so-called cohesion- or cohesion-tension theory, postulates however that the process is physically based on a hydraulic fluid flow with negative pressure in water conducting tubes originating from the leaves. Lower pressure (suction) driven volume flow is physically a branch of mechanics. Moisture absorbed from the soil via the root is thought to be pulled up the stem by the leaves in continuous and tensioned threads of water. It is assumed that the hydraulic Hagen/Poiseuille flow law, derived for tubes, applies in the xylem. In a textbook of botany you can find the opinion: "Just as the pipes of a water pipe supply necessary water to each household, leaf nerves supply water and nutrient salts to each individual cell.” (Translated from German). Many plant physiologists consider this hydraulic principle to be correct, but it does not remain unchallenged. Doubts are repeatedly expressed. The question arises: How does water transport actually take place? It is shown how the diffusive/adsorption transport principle works. The partial dehydration (desorption) of the plant, driven by the diffusive process of transpiration, forms a combined concentration and adsorption-site gradient for water in the xylem matrix. Especially with open stomata the lowest moisture concentration and the highest number of adsorption-sites for water (sites with free van der Waals forces), can be found in the mesophyll cell walls at the liquid/vapor boundary in the leaf. The water taken up by the root moves spontaneously in the direction of this boundary and can thus partially or completely compensate for the existing concentration- and adsorption-site- differences for water. Thus, a thermodynamic overlapping diffusive/adsorptive movement of moisture along the stationary xylem/wood takes place. After the introduction and a review of some controversies with cohesion theory, the physiology of the processes associated with long-distance water displacement is mentioned below. A thermodynamic adsorption hypothesis of the natural water transport in plants, based on known facts, is presented.
ARTICLE | doi:10.20944/preprints202211.0449.v1
Subject: Materials Science, General Materials Science Keywords: organophosphate pesticide; removal; adsorption; kinetics; textural properties
Online: 24 November 2022 (03:19:52 CET)
Due to the accumulation of pesticides in the environment, the development of efficient strategies for their removal is of utmost importance. Activated carbons are currently seen as excellent candidates for adsorptive pesticide removal based on several beneficial properties, like a large surface area, developed porosity, and low price. However, a deep link between materials' properties and performance is still elusive. Here we focus on the kinetics of three organophosphate pesticides removal, aliphatic dimethoate and malathion and aromatic chlorpyrifos, using a series of carefully prepared activated carbon fibers. Used adsorbents have a wide range of specific surface areas, pore size distributions, and elemental content, allowing the establishment of the link between physicochemical properties and their performance as adsorbents. We use data analysis tools to link these properties and discuss their different roles in the removal of three structurally different yet extremely dangerous pesticides. The obtained results can guide the synthesis of novel adsorbents or rationally select adsorbents for specific target pollutants based on the physicochemical properties of adsorbents and the chemical structure of pollutants.
ARTICLE | doi:10.20944/preprints202106.0720.v1
Subject: Arts & Humanities, Anthropology & Ethnography Keywords: Biochar; Cadmium; Pyrolysis temperature; Adsorption kinetics; Desorption
Online: 30 June 2021 (09:10:01 CEST)
Biochar has high potential usage in retaining various contaminants, wastewater treatment, and water purification. In this study, three rice husk derived biochars with pyrolysis temperature 300, 400 and 500 ºC, respectively, and pristine rice rusk were used to remove cadmium from aqueous solution. The results showed that about 70% or more of Cd2+ adsorption occurred in the first 960 mins of adsorption kinetics. The Cd2+ adsorption capacity under equilibrium increased with increasing pyrolysis temperature, probably attributed to the increased specific surface area (SSA) under higher pyrolysis temperature noting that significant linear correlation occurred between Cd2+ adsorption capacity and SSA. The Cd2+ adsorption could be best fitted by pseudo-second order model relative to Elovich model and pseudo-first order model. The Cd2+ adsorption rates were higher in ﬁlm diffusion stage, indicating that ﬁlm diffusion stage was signiﬁcant and fast in the early stage of Cd2+ adsorption. In contrast, Cd2+ adsorption by intra-particle diffusion accounted for 47.0%, 47.9% and 43.9% on average of the total Cd2+ adsorption, respectively, indicating that intra-particle diffusion of Cd2+ played a more predominant role in limiting Cd2+ adsorption rate. When reaching Cd2+ desorption equilibrium, removal ratio (RR) values were averaged 0.96, 0.91, and 0.90 under three initial concentrations. More than 90 percentage on average of Cd2+ was removed from aqueous solution by biochars and rice rusk as well, thus biochars can be used to efficiently remove contaminants from aqueous environment. Cation exchange, electrostatic attraction, and the complexation with surface functional groups could be the main dominant mechanisms for Cd2+ adsorption-desorption on biochars.
ARTICLE | doi:10.20944/preprints202106.0591.v1
Subject: Earth Sciences, Atmospheric Science Keywords: Adsorption; Desorption; Dissipation; Herbicide half-life; Leaching.
Online: 23 June 2021 (16:02:59 CEST)
Chemical weed control using herbicide glyphosate to manage emerged weeds is an important production practice in Florida citrus. Despite the extensive use of glyphosate in citrus orchards, very limited information is available on its environmental fate and behavior in Florida soils that are predominantly sandy in nature. Hence, the study's objective was to understand the adsorption-desorption, dissipation dynamics, and vertical movement or leaching of glyphosate in sandy soils in citrus orchards. Laboratory, field, and greenhouse experiments were conducted at Southwest Florida Research and Education Center in Immokalee, Florida. The adsorption-desorption behavior of glyphosate in the soils from three major citrus production areas in Florida was studied utilizing a batch equilibrium method. The dissipation of glyphosate was tracked in the field following its application at the rate of 4.20 kg ae ha-1. Soil leaching columns in greenhouse conditions were used to study the vertical movement of glyphosate. The results suggest that glyphosate has a relatively lower range of adsorption or binding (Kads = 14.28 to 30.88) in the tested soil types. The field dissipation half-life (DT50) of glyphosate from surface soil was found to be 26 days. Glyphosate moved vertically or leached into the soil profile, up to 40 cm in the soil column, when analyzed 40 days after herbicide application. The primary degradation product of glyphosate, i.e., aminomethyl phosphonic acid (AMPA), was also detected up to the depth of 30 cm below the soil surface, indicating the presence of microbial metabolism of glyphosate in the soil.
REVIEW | doi:10.20944/preprints202105.0140.v1
Subject: Engineering, Automotive Engineering Keywords: Adsorption; Scale Inhibitors; Fine sands; Colloids; Reservoir
Online: 7 May 2021 (10:42:36 CEST)
Scale inhibitors are deployed as preventive and rejuvenation operation in oil and gas industry when production operations are under threat or menace of scale blockage. The application of scale inhibitors is carried out through a method known as squeezing. In general, the squeeze process is governed by inhibitor-rock interaction which is described by adsorption/desorption isotherm. Most reservoirs produce loose sand grains or fine sand which float and flow within the pore spaces along with the squeezed scale inhibitors. Hypothetical reports have shown that not all scale inhibitors pumped into the formation adsorb onto the formation rock. A number of factors (irreversible adsorption, pH changes, competing ions, concentration and temperature) have been considered to affect the adsorption and return profile of these scale inhibitors. This review work examines the performances of most common scale inhibitors used in the oil and gas production activities, theoretical application in reservoirs and how loose fine sand grains affect the adsorption and desorption characteristics of squeezed scale inhibitors. Additionally, presented were overviews of previous reports on fine sand production and migration of fine sands through formation pores in reservoirs.
Subject: Engineering, Automotive Engineering Keywords: Magnetite (Fe3O4); wool keratin; Cu2+ ions; adsorption
Online: 17 March 2021 (11:35:16 CET)
The treatment of wastewater containing heavy metals and the utilization of wool waste are very important for the sustainable development of textile mills. In this study, the wool keratin modified magnetite (Fe3O4) powders were fabricated by using wool waste via a co-precipitation technique for removal of Cu2+ ions from aqueous solutions. The morphology, chemical compositions, crystal structure, microstructure, magnetism properties, organic content, and specific surface area of as-fabricated powders were systematically characterized by various techniques including field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), thermogravimetric (TG) analysis, and BET surface area analyzer. The effects of experimental parameters such as the volume of wool keratin hydrolysate, the dosage of powder, the initial Cu2+ ion concentration, and the pH value of solution on the adsorption capacity of Cu2+ ions by the powders were examined. The experimental results indicated that the Cu2+ ion adsorption performance of the wool keratin modified Fe3O4 powders exhibited much better than that of the chitosan modified ones with a maximum Cu2+ adsorption capacity of 29.2 mg/g under favorable conditions (0.05 g powders; 50 mL of 40 mg/L CuSO4; pH 5; temperature 293 K). The high adsorption capacity towards Cu2+ ions on the wool keratin modified Fe3O4 powders was primarily because of the strong surface complexation of -COOH and -NH2 functional groups of wool keratins with Cu2+ ions. The Cu2+ ion adsorption process on the wool keratin modified Fe3O4 powders followed the Langmuir adsorption isotherm model and the pseudo-second-order adsorption kinetic model. After Cu2+ ion removal, the wool keratin modified Fe3O4 powders were easily separated using a magnet from aqueous solution and efficiently regenerated using 0.5 M EDTA-H2SO4 eluting. The wool keratin modified Fe3O4 powders possessed good regenerative performance after five cycles. This study provided a feasible way to utilize waste wool textiles for preparing magnetic biomass-based adsorbents for the removal of heavy metal ions from aqueous solutions.
ARTICLE | doi:10.20944/preprints202102.0450.v1
Subject: Materials Science, Biomaterials Keywords: Wet spinning; Lanthanum oxide; Biochar; Chromate; Adsorption
Online: 22 February 2021 (08:51:53 CET)
Lanthanum chemical compound incorporates a sensible anionic complexing ability, however lacks stability at low pH scale. Biochar fibers will benefit of their massive space and plethoric useful teams on surface to support metal chemical compound. Herein, wet spinning technology was used to load La3+ onto sodium alginate fiber, and convert La3+ into La2O3 through carbonization. The La2O3 modified biochar (La-BC) fiber was characterized by SEM, XRD and XPS, etc. The adsorption experiment proved that La-BC showed excellent adsorption capacity for chromates, and its saturation adsorption capacity was about 104.93mg/g. The information suggested that the adsorption was in step with both Langmuir and Freundlich model, followed pseudo-second-order surface assimilation mechanics, which instructed that the Cr (VI) adsorption was characterized by single-phase and polyphase adsorption, mainly chemical adsorption. Thermodynamic parameter proved that the adsorption process was spontaneous and endothermic. The mechanistic investigation revealed that the mechanism of adsorption of Cr (VI) by La-BC may include electrostatic interaction, ligand exchange or complexation. Moreover, co-existing anions and regeneration experiments proved that La-BC was recyclable and had a good prospect in the field of chrome-containing wastewater removal.
Subject: Chemistry, Analytical Chemistry Keywords: mixed oxide-LDHs; manganese; wastewater; adsorption kinetics
Online: 17 July 2020 (09:14:45 CEST)
In this study, Mg-Al and Mg-Al-Ni - layered double hydroxides (LDHs) were successfully synthesized for efficient removal of Mn2+ from synthetically wastewater. LDH adsorbents (Mg-Al and Mg-Ni-Al) were prepared by co-precipitation method. The formation of the layered double hydroxide, the adsorption of manganese on both LDH (Mg-Al and Mg-Ni-Al) were observed by XRD, SEM and EDX analysis. The various parameters such as the effect of shaking time, initial Mn2+ concentration, temperature were controlled and optimized to removal of Mn2+ from synthetic wastewater. The kinetics and adsorption isotherms for Mn2+ removal from wastewater were studied in batch mode. At temperatures of 10 °C and 20 °C the adsorption equilibrium was reached after 24 h. Adsorption isotherms of Mn2+ are well fitted by Langmuir and Freundlich isotherm equation. The adsorption capacity of Mn2+ from synthetic wastewater of 80.607 mg/kg was obtained for (Mg-Al-Ni)-LDH. It is found that the adsorption kinetics is best described by the pseudo-second order model. These results prove that LDHs can be considered as a potential material for adsorption of Mn2+ from wastewater.
Subject: Chemistry, Chemical Engineering Keywords: adsorption; lead; biocomposite; alginate; Ficus carica L.
Online: 7 May 2020 (08:03:17 CEST)
In this study, fig leaves, zeolite and alginate were used to prepare a biocomposite for the adsorption of Pb(II) ions from aqueous solutions. Effects of various parameters on the biosorption process such as pH, temperature, initial lead concentration and contact time have been investigated. Maximum uptake of Pb(II) ions (85%) has been achieved at pH 6, with 25 mg/L of initial concentration and at a temperature of 288.15 K. Among the applied models, the data correlated well with Freundlich and D-R models and it was established that the biosorption was physical in nature. The amount of adsorbed lead per gram of sorbent was found to be 150.3 mg/g. Thermodynamic parameters showed the exothermic heat of biosorption and the feasibility of the process. Results have suggested that the prepared biosorbent possesses promising biosorption potential.
ARTICLE | doi:10.20944/preprints202001.0254.v1
Subject: Materials Science, Metallurgy Keywords: adsorption; Lanthanum; Cerium; carbon nanotubes; rare earth
Online: 22 January 2020 (03:21:11 CET)
Since the 1960s Rare earths (REs) applications gradually have expanded to everyday life. REs have great strategic importance in industrial and technological development, so it is expected an increase in their demand. Among the REs the European Commission considered Cerium and Lanthanum as critical raw materials. This research article studies the adsorption of Ce and La onto two carbon nanomaterials, multiwalled carbon nanotubes (MWCNT) and carboxylic functionalized multiwalled carbon nanotubes (MWCNT_ox). The latter has slightly more affinity for REs than MWCNT. The recovery percentage for Ce were 89 and 98% and in the case of for La were 99 and 92% using 0.8 g of MWCNT and 0.2 g of MWCNT_ox respectively. The adsorption process fits a pseudo second-order kinetic model and the Langmuir isotherm best represented the metal uptake.
ARTICLE | doi:10.20944/preprints201910.0257.v1
Subject: Materials Science, Nanotechnology Keywords: adsorption; chitosan; isotherm; nanochitosan; pb (ii) removal
Online: 22 October 2019 (10:35:50 CEST)
In this work, nanochitosan (NC) was prepared through ionic gelation using low-molecular-weight chitosan and maleic acid (MA). The synthesized NC was charac¬terized by means of Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). In the course of preparation, the particle size of the material was strongly depended on the parameters such as chitosan concentration and pH of the solution. By controlling the above parameters, NC with the size of smaller than 100 nm was prepared. The chitosan and prepared NC were used for the adsorption of Pb (II) from aqueous solutions in a batch system. Among the sorption parameters, pH showed the strongest effect on the sorption process and maximum Pb (II) removal was obtained at pH value of 6. The pseudo-first-order and pseudo-second-order were used to track the kinetics of adsorption process. Langmuir and Freundlich isotherms were subjected to sorption data to estimate the sorption capacity. NC proved to be an excellent adsorbent with remarkable capacity to remove Pb (II) ions from the aqueous solutions at various concentrations. The NC also showed incredible performance with a comparatively easier preparation process than other reported work.
ARTICLE | doi:10.20944/preprints201908.0076.v1
Subject: Chemistry, Applied Chemistry Keywords: dysprosium; activated carbon; spent coffee ground; adsorption
Online: 6 August 2019 (12:23:23 CEST)
This paper describes the physico-chemical study of the adsorption of dysprosium (Dy3+) in aqueous solution onto two types of activated carbons synthesized from spent coffee ground. KOH activated carbon is a microporous material with a specific BET surface area of 2330 m2·g-1 and pores with a diameter of 3.2 nm. Carbon activated with water vapor and N2 is a solid mesoporous, with pores of 5.7 nm in diameter and a specific surface of 982 m2·g-1. A significant dependence of the adsorption capacity on the solution pH was found, while it does not depend significantly neither on the dysprosium concentration nor on the temperature. A maximum adsorption capacity of 31.26 mg·g-1 and 33.52 mg·g-1 for the chemically and physically activated carbons, respectively, were found. In both cases, the results obtained from adsorption isotherms and kinetic study were better fit to a Langmuir model and a pseudo-second-order kinetics. In addition, thermodynamic results indicate that dysprosium adsorption onto both activated carbons is an exothermic, spontaneous and favorable process.
ARTICLE | doi:10.20944/preprints201811.0413.v1
Subject: Engineering, General Engineering Keywords: Citrus aurantifolia Swingle; hesperidin; citrus byproducts; adsorption
Online: 19 November 2018 (04:14:44 CET)
The processing of Mexican limes generates great amounts of peel as a byproduct. Lime peel is mainly rich in the flavonoid hesperidin, whose bioactivity is oriented mainly to cardiovascular diseases and cancer. The purpose of this work was to develop a green process for the extraction and purification of hesperidin from Mexican lime peel. The extraction of hesperidin was investigated on a laboratory scale by varying the solvent composition and the solid-to-solvent ratio. The best conditions (solid-to-solvent ratio of 0.33 g/mL and 60% ethanol) were used for the extraction of hesperidin in a pilot scale (Volume = 20 L). The kinetics of the extraction was studied to find the maximum hesperidin concentration at 100 min. The concentrated extract had a hesperidin content of 0.303 mg/mL. Next, a purification process using adsorption resins was assessed. Through static tests, it was determined that higher adsorption efficiencies were achieved with the EXA-118 resin and diluted extract (4:6 ratio with 10% DMSO). Finally, the adsorption of hesperidin from the diluted extract (hesperidin concentration of 0.109 mg/mL) was carried out at 25 °C in a column packed with 80 mL of EXA-118 resin. The mean recovery efficiency of hesperidin from the extract was almost 90%.
REVIEW | doi:10.20944/preprints201809.0336.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Adsorption; Emerging contaminants; Biomass; Biochar; Activated carbon
Online: 18 September 2018 (09:06:00 CEST)
This review analyzes the synthesis and characterization of biomass-derived carbons for adsorption of emerging contaminants from water. The study begins with the definition and different types of emerging contaminants more often founded in water streams and the different technologies available for their removal including adsorption. It also describes the biomass sources that could be used for the synthesis of biochars and activated carbons. The characterization of the adsorbents and the different approaches that could be employed for the study of the adsorption processes are also detailed. Finally, the work reviews in detail some studies of the literature focused on the adsorption of emerging contaminants on biochars and activated carbons synthesized from biomass precursors.
ARTICLE | doi:10.20944/preprints201705.0112.v1
Subject: Chemistry, Physical Chemistry Keywords: adsorption; magadiite; cationic clay; methylene blue; remediation
Online: 15 May 2017 (12:14:05 CEST)
The removal of methylene blue (MB) dye from water was investigated using synthetic nano-clay magadiite (SNCM). SNCM was synthesized by hydrothermal treatment under autogenous pressure. A rosette-shaped single mesoporous magadiite phase with 16.63 nm average crystallite size and 33 m2.g-1 BET-surface area was recorded. The adsorption results indicated the pronounced affinity of the SNCM to the MB dye molecules which reached adsorption uptake of 20.0 mg MB dye/g of SNCM. The elimination of MB dye by the SNCM was kinetically and thermodynamically considered; a pseudo second order kinetic model was attained, and a spontaneous, chemical, and exothermic in nature was verified.
ARTICLE | doi:10.20944/preprints202301.0295.v1
Subject: Materials Science, General Materials Science Keywords: Gas sensor; Jarosite; Manganite; Composite ceramic; Gas adsorption.
Online: 17 January 2023 (06:08:41 CET)
This report aimed to know the performance of local mineral-based composite ceramic. The materials used consist of Indonesian local minerals, which are jarosite and manganite minerals as sources of oxide iron and Mangan. The materials were synthesized using the precipitation method, whereas composite ceramic was fabricated using a screen printing method and fired at 600 oC using a furnace. The results of the characterizations indicate that the sample forms three phases on diffraction peaks. The differences in the resistance values in ambient and ethanol environments indicate that the sample has very different responses. The high porosity of the sample greatly support the gas adsorption process. Thus, the sample has a high level of sensitivity. With the above characteristics, the composite ceramic which was fabricated has the potential to be applied to gas sensors, especially ethanol gas sensors.
ARTICLE | doi:10.20944/preprints202110.0186.v1
Subject: Chemistry, Applied Chemistry Keywords: Adsorption; DFT; Starch-based Activated Carbon; Kinetics; Thermodynamics
Online: 12 October 2021 (14:58:07 CEST)
Cadmium (II) contamination in the environment is an emerging problem due to its acute toxicity and mobility, so it is very urgent to remove this species from industrial wastewater before it is discharged into the environment. Thus, a starch-based activated carbon (AC) with a specific surface area of 1600 m2g-1 is used as an adsorbent for the capturing of toxic Cadmium (II) ions from synthetic solution. The sorbent is characterized by BET, SEM, TEM, XRD, FT-IR, TGA, and zeta potential. The maximum uptake (284 mg g-1) of Cadmium (II) ion is obtained at pH 6. The thermodynamics parameters like ∆G, ∆H, ΔS are found to be -17.42 kJmol-1, 6.49 kJ mol-1, and 55.66 Jmol-1K-1 respectively, revealing that the adsorption mechanism is endothermic, spontaneous, and feasible. The experimental data follows the D-R and Langmuir models well. The mass transfer is controlled by pseudo 2nd order kinetics. Furthermore, the density functional theory simulations demonstrate that the activated carbon strongly interacted with the Cd (II) ion through its various active sites. The adsorption energy noted for all interactive sites is highly negative (-0.45 eV to -10.03 eV), which shows that the adsorption process is spontaneous and stable which is in agreement with the experimental thermodynamics analysis.
ARTICLE | doi:10.20944/preprints202107.0292.v2
Subject: Chemistry, Analytical Chemistry Keywords: Activated carbon; adsorption; ciprofloxacin; pollutant; pumpkin seed; thermodynamics
Online: 14 July 2021 (14:12:02 CEST)
Antibiotics are among the most critical environmental pollutant drug groups. One of the methods used to remove this pollution is adsorption. In this study, activated carbon was produced from the pumpkin seed shell and then modified with KOH. This adsorbent obtained was used in the re-moval of ciprofloxacin from aqueous systems. Fourier Transform-Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), elemental, X-ray Photoelectron Spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and Zeta analyzes were used for the characterization of the ad-sorbent. In particular, the surface area was found to be a very remarkable value of 2730 m2/g. The conditions of the adsorption experiments were optimized based on interaction time, adsorbent amount, pH and temperature. Over 99% success has been achieved in removal works carried out under the most optimized conditions. In addition, it was determined that the Langmuir isotherm is the most suitable model for the adsorption interaction.
ARTICLE | doi:10.20944/preprints202106.0325.v1
Subject: Chemistry, Chemical Engineering Keywords: Poultry litter; Carbon nanotubes; Catalyst; Experimental conditions; Adsorption
Online: 11 June 2021 (14:59:33 CEST)
Pakistan being an agricultural country is raising 146.5 million commercial and domestic poultry birds which generate around 544,831 tons of waste. This waste finds its final disposal in agricultural land as soil fertilizer or disposal site amendment. The uncontrolled use of poultry litter for this purpose results in environmental impacts such as the emission of methane, a greenhouse gas. However, other options like thermochemical conversion of this waste can offer a better solution wherein poultry litter can be used as low-cost carbon sources for the synthesis of Carbon Nanotubes (CNTs). In this study, efforts have been made to utilize this cheap and plenty of available carbon source for synthesis of CNTs in the presence of Ni/Mo/MgO as a catalyst, through pyrolysis. The optimum mole ratio of catalyst (4:0.2:1) was found to yield more carbon product. Furthermore, process parameters such as temperature, time, polymer & catalyst weight were also optimized. The best possible process parameters that resulted (pyrolysis time (12 min), temperature (825◦C), and catalyst weight (100 mg) good yield of CNTs . The structure and morphology of produced nanotubes were confirmed through X-ray Diffractometer (X-RD) & Scanning Electron Microscopy (SEM). The environmental application of the nanotubes was tested in synthetic chromium solution in the lab using a batch experiment. Different experimental conditions (pH, adsorbent dosage and contact time) were optimized to enhance the adsorption of Cr (VI) by carbon nanotubes and UV-Visible spectrophotometer was used at 540nm to measure the absorbance of Cr (VI). Results show that up to 81.83% of Cr (VI) removal was achieved by using 8 mg of CNTs at pH 3 with 400 rpm at 180 min of contact time. Thus, it was concluded that poultry litter can be a useful source for the synthesis of CNTs and thereby removal of Cr (VI) from industrial tanneries wastewater.
ARTICLE | doi:10.20944/preprints202008.0599.v1
Subject: Chemistry, Physical Chemistry Keywords: polypropylene; suspension grafting; melt-blown spinning; adsorption; aniline
Online: 27 August 2020 (08:27:29 CEST)
This paper uses polypropylene (PP) as the matrix and acrylic acid (AA) and maleic anhydride (MAH) as functional monomers to prepare PP-g-(AA-MAH) fibers by suspension grafting and melt-blown spinning technology that are easy to industrially scale-up. The fibers can be used to adsorb aniline from wastewaters. Results showed that the grafting ratio reached the maximum of 12.47%. The corresponding optimal conditions were grafting time of 3h, AA : MAH = 0.75, total monomer content of 55%, benzoyl peroxide 1.4%, xylene concentration of 6 mL/g PP, and deionized water content of 8 mL/g PP. Owing to its good fluidity and thermal stability, the product of suspension grafting can be used for melt-blown spinning. Infrared spectroscopic and nuclear magnetic resonance spectroscopic analyses indicated that AA and MAH were successfully grafted onto PP fibers. After grafting, the hydrophilicity of PP-g-(AA-MAH) fiber increased. Therefore, it had higher adsorptivity for aniline and the adsorption capacity could reach 42.2 mg/g at 45 min. Moreover, the PP-g-(AA-MAH) fibers showed good regeneration performance.
ARTICLE | doi:10.20944/preprints202002.0369.v1
Subject: Engineering, Energy & Fuel Technology Keywords: Solar Cooling; Adsorption; Evacuated tube collectors; Experimental testing
Online: 25 February 2020 (11:12:51 CET)
The high environmental impact of conventional methods of cooling and heating has increased the need for renewable energy deployment for covering thermal loads. Towards that direction, the proposed system aims at offering an efficient solar powered alternative, coupling a zeolite-water adsorption chiller with a conventional vapor compression cycle. The system is designed to operate under intermittent heat supply of low-temperature solar thermal energy (<90 °C) provided by evacuated tube collectors. A prototype was developed and tested in cooling mode operation. The results of separate components testing showed that the adsorption chiller was operating efficiently, achieving a maximum coefficient of performance (COP) of 0.65. With respect to the combined performance of the system, evaluated on a typical week of summer in Athens, the maximum reported COP was approximately 0.575, mainly due to the lower driving temperatures at a range of 75 °C. The corresponding mean energy efficiency ratio (EER) obtained was 5.8.
ARTICLE | doi:10.20944/preprints201811.0140.v1
Subject: Chemistry, Chemical Engineering Keywords: Smithsonite; Flotation; 2-(Hexadecanoylamino)acetic acid; Collector; Adsorption
Online: 6 November 2018 (11:59:07 CET)
Zinc is mostly extracted from zinc oxide and sulfide minerals, and this process involves flotation as a key step. While it is easier to float the sulfide mineral, its consumption and depletion has led to an increased reliance on zinc oxide minerals, including smithsonite; hence the development of efficient ways of collecting smithsonite by flotation is an important objective. Herein, we describe the use of 2-(hexadecanoylamino)acetic acid (HAA), a novel surfactant, as a collector during smithsonite flotation. The mechanism and flotation performance of HAA during smithsonite flotation were investigated by total organic carbon (TOC) content studies, zeta potential measurements, FTIR spectroscopy, and XPS analyses, combined with micro-flotation experiments. The flotation results revealed that HAA is an excellent collector in pulp over a wide pH range (9–12) and at a relatively low concentration (2 × 10‒4 mol/L), at which a recovery of close to 90% of the smithsonite mineral was obtained. TOC-content studies reveal that the good flotation recovery is ascribable to large amounts of collector molecule adsorbed on the smithsonite surface, while zeta potential measurements show that the HAA is chemically adsorbed onto the smithsonite. FTIR and XPS analyses reveal that the HAA-collector molecules adsorb onto the smithsonite surface as zinc-HAA complexes involving carboxylate moieties and Zn sites on the smithsonite surface in alkaline solution.
ARTICLE | doi:10.20944/preprints201810.0769.v1
Subject: Engineering, Civil Engineering Keywords: Bentonite; Sawdust; Chemically treatment; Heavy metal; Adsorption capacity
Online: 1 November 2018 (18:18:19 CET)
In recent years, the need for safe and modern composite barrier for the prevention of groundwater contamination and the provision of Geo-environmental protection has been studied together with the need of designing low cost and effective liner for isolating landfill contents from the environment. In this study, various mix designs involving two natural adsorbents, the Na-Bentonite and the pH-adjusted sawdust were prepared for a series of Geo-environmental experiments to be carried out to determine the adsorption capacity, buffering capacity, pH changes, and COD changes among others, in the presence of Pb(NO3)2 contaminant concentrations. Generally, the results showed an increase in adsorption capacity in the acidic segment of the treatment. An increase of 58% of the adsorption efficiency of the Na-Bentonite in adsorbing the contaminant at the highest concentration was the most important achievement of the system while in the acidic segment.
ARTICLE | doi:10.20944/preprints201809.0190.v1
Subject: Earth Sciences, Geochemistry & Petrology Keywords: zeolite; ion-exchange; adsorption; ammonium; Si/Al; temperature
Online: 11 September 2018 (08:50:29 CEST)
We investigate the ammonium removal abilities of natural and synthetic zeolites, which have distinct Si/Al ratios and various surface areas, to study how adsorption and ion-exchange processes in zeolites perform under different ammonium concentrations and different temperatures. Five zeolites including natural mordenite, chabazite, erionite, clinoptilolite and synthetic merlinoite were immersed in 20 mg/kg, 50 mg/kg and 100 mg/kg ammonium solutions. The results demonstrate that zeolites under high ammonium concentrations (100 mg/kg) possess higher physical adsorption capacity (0.398–0.468 meq/g), whereas those under lower ammonium concentrations (20 mg/kg) possess greater ion-exchange property (64–99%). The ion-exchange ability of zeolites are extremely dependent on the cation content of the zeolites, and the cation content is affected by the Si/Al ratio. The surface area of zeolites also has a partial influence on its physical adsorption ability. When the surface area is less than 100 m2/g, the adsorption ability of zeolite increases obviously with surface area; however, adsorption ability is saturated as the surface area becomes larger than this critical value of 100 m2/g. When we carried out the zeolites in 50 mg/kg ammonium concentration at different temperatures (5~50 ℃), we found that zeolites exhibit the highest ammonium removal ability at 30°C and the potassium release was enhanced at 30~40 ℃.
REVIEW | doi:10.20944/preprints202212.0043.v1
Subject: Chemistry, Other Keywords: adsorption; GBV; heavy metals; secondary pollution; spent adsorbent reuse
Online: 2 December 2022 (08:43:18 CET)
Water contamination has intensified over the year as the world's population and industrial activities have grown. Heavy metals (HMs) are amongst the environmental contaminants commonly found in water and wastewater. These include Lead, Manganese, Chromium, Mercury, etc. Various techniques have been used to remediate this environmental challenge and adsorption has proven to be more effective because it is simple to use, excellent efficiency, low cost, possibility to operate in several experimental conditions. Regrettably, this method yields waste materials, which represents a scaling restriction. Furthermore, after the HM has been removed and loaded onto the adsorbent, there is still a question of the fate of the metal-loaded adsorbent. Most of the time these metal loaded adsorbents are discarded in the environment and constitute a secondary pollution. New applications for heavy metals laden have been investigated. This review article presents the various applications that had been investigated to reuse the loaded metal adsorbent. A case study on developing tools for combatting gender-based violence (GBV) has also been discussed.
ARTICLE | doi:10.20944/preprints202210.0133.v1
Subject: Earth Sciences, Environmental Sciences Keywords: cyanidation wastewater; cyanide; photodegradation; adsorption; clay; blast furnace sludge
Online: 11 October 2022 (03:25:22 CEST)
This research is mainly focused on the evaluation of TiO2/Fe2O3 composite and two industrial types of waste (kaolin (Clay-K) and a blast furnace sludge (BFS)) as adsorbent materials of cyanide and as photocatalysts. First, adsorption tests were performed in the absence of light. During photodegradation experiments, the effect of the type of irradiation (ultraviolet (UV) light), visible light and natural sunlight), irradiation time, the type of photocatalyst, as well as irradiance in case of natural sunlight use, were investigated. Adsorption results indicate that Clay-K and TiO2/Fe2O3 materials adsorb approximately twice as much cyanide compared to the BFS sample, which only adsorbs 33.3% (124.87 mg/g); this is due to its smaller specific surface area (5.69 m2/g) compared to that of the other two materials (Clay-K and TiO2/Fe2O3 (14.93 m2/g and 66.59 m2/g, respectively). The results obtained from the study of photodegradation of cyanide under UV irradiation, indicate that Clay-K and BFS samples photodegrade cyanide by 96.44% and 92.66%, respectively. On the other hand, using UV irradiation plus solar irradiation and visible plus solar irradiation, the best photocatalyst was the TiO2/Fe2O3, with 98.66% photodegradation. The use of natural sunlight (irradiance of 600 to 800 W/m2) of a NaCN solution of 750 mg/L, the BFS material was the most efficient to photodegrade cyanide, obtaining 97% in two hours and 87% in just 30 minutes of irradiation.
ARTICLE | doi:10.20944/preprints202112.0319.v1
Subject: Earth Sciences, Environmental Sciences Keywords: Waste water; Phosphate co-product; Adsorption; Red Acid 52
Online: 21 December 2021 (09:15:16 CET)
Water is essential for all living things however its pain has become serious. Many industrial activities cause its pollution by the release of polluting byproduct. Waste water treatment is hence necessary. In this context, the waste water of the textile industry containing Red Acid 52 was treated by the solid waste of the washed natural phosphate byproduct. Natural phosphate was also studied. The solid materials were first characterized by chemical analysis, Fourier Transform Infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The phosphate materials were after that, tested in the adsorption of the Red Acid 52. The experimental data indicated that the phosphate waste rock allowed the removal of Red Acid 52. Its maximum retention capacity attained 18.4 mg.g-1. Calcinations of materials inhibits the removal capacity found reduced by 60 to 70%. The adsorption kinetics of the Red Acid 52 on the material is well described by the pseudo second order model while the adsorption isotherms are identified by the Langmuir model. Hereafter, the thermodynamic study revealed that the adsorption process is spontaneous and exothermic. Keywords: Waste water, Phosphate co-product, Adsorption, Red Acid 52.
ARTICLE | doi:10.20944/preprints202112.0002.v1
Subject: Life Sciences, Biochemistry Keywords: ammonia; emission control; saturation point; absorption tower; adsorption reactor
Online: 1 December 2021 (10:22:31 CET)
Ammonia known as harmful gas that could impact on health and environment. Typically, ammonia gas emitted by fertilizer industry, rubber factory, etc. There are many options for advance industry to control ammonia gas pollution, absorption tower using water scrubber and using activated carbon as adsorption reaction could be an option. But for middle- and lower-class industry, it is common in Indonesia, as seen on many rubber factories, ammonia gas pollution is serious problem to control, actually they have used wet scrubber but eficiency is lower about 47%. This study measure performance for ammonia elimination as gas pollutant using absorption tower and adsorption tower in laboratory scale. Using electrochemical gas sensor, we measure both ammonia concentration for inlet and outlet simultaneously to settle saturation point of these two types of ammonia emission control. In conclusion, Ammonia absorbed in water proportional to saturation time and absorbent volume. Highest absorbed ammonia concentration 1.538 mg/L on 4000 mL absorbent. For Adsorption system, saturation time proportional and correlated to adsorbent weight and Adsorption capacity reverse correlated to adsorbent weight. Optimum adsorption point can be achieved from intersection curve between saturation time and adsorption capacity which is 1200 grams adsorbent
ARTICLE | doi:10.20944/preprints202110.0157.v1
Subject: Chemistry, Chemical Engineering Keywords: Adsorption; Cane Papyrus; Oily water; Produced water; Isotherm; Kinetic
Online: 11 October 2021 (11:53:37 CEST)
High quantities of wastewater produced from producing natural gas and oil from the aquifer, which called produced water. The produced water was comprised of dissolved solids, suspended solids, emulsified oil, and organic and inorganic compounds. That should be treated it's before disposal because it causes harm to the environment. This study takes the produced water from the southern Iraqi oilfield drilling company to adsorption by the Cane papyrus as natural and low-cost adsorbent. The analysis completed by using Fourier transforms infrared spectroscopy, EDX spectra and Scanning Electron Microscopic (SEM) for Cane papyrus. Investigating the effect of many parameters such as adsorbent dosage, temperature, solution pH, mixer speed and contact time. The Langmuir, Freundlich, Temkin and Harkins-Henderson isotherm models were tested, the results were 0.998,0.966, 0.931 and 0.966 respectively. The Langmuir model was more suitable described the adsorption process than the other models. The kinetics results were, 0.984 for Pseudo-first-order, 0.938 for Pseudo-second order is, 0.979 for Intra particle diffusion study and 0.912 for the Elovich model, the Pseudo-first-order kinetic equation best described the kinetics of the reaction. The thermodynamics study effect temperature changes on the thermodynamic parameters such as standard free energy change (∆G°), standard enthalpy change (∆H°) and standard entropy change (∆S°). The experimental data obtained demonstrated that Cane papyrus is a suitable adsorbent for removing oil from produced water.
ARTICLE | doi:10.20944/preprints202109.0331.v1
Subject: Chemistry, Applied Chemistry Keywords: Adsorption; DFT; Cadmium(II) ion; Activated carbon; Kinetics; Thermodynamics
Online: 20 September 2021 (12:22:22 CEST)
Cadmium(II) contamination in the environment is an emerging problem due to its acute toxicity and mobility, so it is very urgent to remove this species from industrial wastewater before it is discharged into the environment. Thus, a starch-based activated carbon (AC) with a specific surface area of 1600 m2g-1 is used as an adsorbent for the capturing of toxic cadmium(II) ions from synthetic solutions. The sorbent is characterized by BET, SEM, TEM, XRD, FT-IR, TGA, and zeta potential. The maximum uptake (284 mg g-1) of Cadmium(II) ion is obtained at pH 6. The thermodynamic parameters like ∆G, ∆H, ΔS are found to be -17.42 kJmol-1, 6.49 kJ mol-1, and 55.66 Jmol-1K-1 respectively, revealing that the adsorption mechanism is endothermic, spontaneous, and feasible. The experimental data follows the D-R and Langmuir models well. The mass transfer is controlled by pseudo 2nd order kinetics. Furthermore, the density functional theory simulations demonstrate that the activated carbon strongly interacted with the Cd(II) ion through its various active sites. The adsorption energy noted for all interactive sites is highly negative (-0.45 eV to -10.03 eV), which shows that the adsorption process is spontaneous and stable which is in agreement with the experimental thermodynamics analysis.
ARTICLE | doi:10.20944/preprints202103.0123.v1
Subject: Materials Science, Biomaterials Keywords: fly ash waste; platinum nanoparticles; industrial dyes; adsorption; photodegradation
Online: 3 March 2021 (10:03:12 CET)
New materials are obtained by transforming fly ash wastes into a valuable composite, with tandem adsorption and photodegradation properties. Mild hydrothermal synthesis, from titanium dioxide, Platinum nanoparticles and zeolite materials obtained from a waste, fly ash, as support, was involved in the composite preparation. The Platinum nanoparticles extended the photocatalytic activity of the composite in Visible range (Eg = 2.1 eV). The efficiency of tandem adsorption and photocatalytic activity of the new composite were evaluated to 80.70% for Bemacid Blau and 93.89% for Bemacid Rot, after 360 min, the irradiation time, with H2O2 addition.
Subject: Chemistry, Analytical Chemistry Keywords: Azolium MOFs; Dye adsorption; Post modification; Cross-coupling reactions
Online: 30 November 2020 (14:14:52 CET)
Two ligands, 1, 3-bis(4-carboxyphenyl)imidazolium chloride and 4, 4՛-bipyridine, were employed to prepare nickel and zinc azolium based MOFs, 1 and 2 by the mixed ligand solvothermal approach. The positively charged azolium moieties in the imidazolium linker resulted in a charged environment in the as-synthesized frameworks. As a result, 1 and 2 demonstrated preferential adsorption of CO2 over methane molecules in the gas phase adsorption due to the higher quadruple moment of CO2, which interacts more with the positively charged frameworks. Besides, in aqueous media, 1 and 2 exhibited incredible adsorption efficiency for anionic dyes. In the following, MOF 1 was metallated at the carbene site of the azolium linker to generate the novel heterogeneous catalyst 1-Pd, which was successfully applied for Sonogashira and Suzuki-Miyaura coupling reactions without losing its activity after three cycles.
ARTICLE | doi:10.20944/preprints202010.0448.v1
Subject: Chemistry, Analytical Chemistry Keywords: Cellulose; agricultural waste; bioadsorbent; rare earth; terbium adsorption-desorption
Online: 22 October 2020 (09:00:24 CEST)
Preparation of a low-cost cellulose-based bioadsorbent from the cellulosic material extracted from the rose stems (CRS) was carried out; rose stems were considered agricultural wastes. After the required pretreatment of this waste, and its further treatment with an acidic mixture of acetic and nitric acids, the CRS product was yielded. The resulting bioadsorbent was characterized by several techniques, such as X-ray diffraction, which revealed diffraction maxima related to cellulose structure, whose calculated crystallinity index (CrI) was 75 %. In addition, Fourier Transform Infrared spectroscopy (FTIR), 13C Nuclear Magnetic Resonance (NMR), and X-ray Photoelectron Spectroscopy (XPS) showed signs of acetylation of the sample, also, the thermal properties of the solid was evaluated through Thermogravimetric Analysis (TGA). Scanning Electron Microscopy (SEM) showed cellulose fibers before and after the adsorption process, some particles with not regular shapes were also observed. The CRS bioadsorbent was used in the effective adsorption of valuable Tb(III) from aqueous solution. The adsorption data resulted in a better fit to the Freundlich isotherm, and pseudo-second-order kinetic models; however, chemisorption had not been ruled out. Finally, desorption experiments revealed a recovery of terbium ions with an efficiency of 97 % from terbium-loaded bioadsorbent.
Subject: Chemistry, Physical Chemistry Keywords: CO2 capture; Activated carbon; Carbon nanomaterials; Adsorption; Surface area.
Online: 8 April 2020 (11:37:06 CEST)
Carbon dioxide (CO2), a major greenhouse gas, capture and separation has recently become a crucial technological solution to reduce atmospheric emissions from fossil fuel burning. Thereafter, many efforts have been put forwarded to reduce the burden on climate change by capturing and separating them especially from larger power plants by the utilization of different technologies. Those technologies have often suffered from high operating cost and huge energy consumption. On right side, physical process such as adsorption is very cost effective process which have been widely used to adsorb different contaminants including CO2. Henceforth, this review covers the overall efficacies of CO2 capture by the utilization of carbon based materials through adsorption technology. Subsequently, we also address the associated challenges and future opportunities of carbon based materials (CBMs). For CO2 capture, it was found that CBMs followed the order of carbon nanomaterials (i.e., graphene, graphene oxides, carbon nanotubes and their composites) < mesoporous -microporous or hierarchical porous carbons < biochar and activated biochar < activated carbons.
Subject: Chemistry, Chemical Engineering Keywords: hypercrosslinked polymer; p-hydroxy-phthalic acid; pollutants; adsorption; biodegradation
Online: 17 September 2019 (11:36:51 CEST)
Adsorption is an effective strategy for the removal of pollutants from the wastewater. Herein, a 2-hydroxyterephthalic acid (HTC) modified hypercrosslinked polymer (HTC-HCP) is successfully synthesized via Friedel-Crafts reactions, and used as an adsorbent for the different types of pollutants including organic contaminants and heavy metal ions from wastewater. Excellent adsorption capacities are observed for amines (aniline, p-methylaniline (p-MA), p-chloroaniline (p-CA), and p-aminobenzoic acid (p-ABA)), phenols (phenol, p-chlorophenol (4-CP) Bisphenol A (BPA), 1-Naphthol (1-NP)), dyes (rhodamine B (RhB) and methyl orange (MO)), and metal ions (Pb2+, Hg2+, and Cd2+). The resulting polymers exhibited excellent adsorption performance towards these pollutants. Especially, the removal rate of aniline is above 95% in the concentration of 2.5 mg/L in 40 min at 25 °C. The interaction mechanism has been investigated, and confirmed by FTIR and the theoretical calculation results. It is due to surface complexation and chemisorption between adsorbent and adsorbate. The polymer exhibits good performance such as high adsorption capacity, high separation efficiency, biodegradable properties, and easy regeneration, suggesting that its potential technological applications for the removal of organic compounds and heavy metal ions from actual industrial effluent.
ARTICLE | doi:10.20944/preprints201804.0080.v2
Online: 2 August 2018 (08:46:23 CEST)
β-dicalcium silicate (β-Ca2SiO4, or β-C2S in cement chemistry notation) is one of the most important minerals in cement. An improvement of its hydration rate would be the key point for developing environmentally friendly cements with lower energy consumption and CO2 emissions. However, there is a lack of fundamental understanding on the water/β-C2S surface interactions. In this work we aim to evaluate the water adsorption on three β-C2S surfaces at the atomic scale using density functional theory (DFT) calculations. Our results indicate that thermodynamically favorable water adsorption takes place in several surface sites, with a broad range of adsorption energies (−0.78 to −1.48 eV), depending on the particular mineral surface and adsorption site. To clarify the key factor governing the adsorption, the electronic properties of water at the surface were analyzed. The partial density of states (DOS), charge analysis, and electron density difference analyses suggest a dual interaction of water with β-C2S (100) surface: a nucleophilic interaction of the water oxygen lone pair with surface calcium atoms, and an electrophilic interaction (hydrogen bond) of one water hydrogen with surface oxygen atoms. Despite the elucidation of the adsorption mechanism, no correlation was found between the electronic structure and the adsorption energies.
ARTICLE | doi:10.20944/preprints201807.0205.v1
Subject: Materials Science, Nanotechnology Keywords: γ-alumina; nanocomposite particle; epoxide functionality; adsorption; Remazol navy.
Online: 11 July 2018 (14:29:57 CEST)
In this investigation magnetic γ-Al2O3 ceramic nanocomposite particles bearing epoxide functionality are prepared following a multistep process. The ultimate nanocomposite particles are named as γ-Al2O3/Fe3O4/SiO2/poly(glycidyl methacrylate (PGMA). The surface property is evaluated by carrying out the adsorption study of Remazol navy (RN), a model reactive azo dye, on both γ-Al2O3/Fe3O4/SiO2 and γ-Al2O3/Fe3O4/SiO2/PGMA nanocomposite particles. The adsorption is carried out at the point of zero charge (PZC) to neutralize the effect of particle surface charge. The adsorption rate is very fast, reached equilibrium (qe) value within five min. Due to mesoporous structure of silica layer γ-Al2O3/Fe3O4/SiO2 nanocomposite particles possessed relatively higher specific surface area and magnitude of adsorption is dependent on the total specific surface area. The introduction of epoxide functionality favored high adsorption capacity in mass per unit surface area. The adsorption process strictly followed Langmuir model. Thermodynamic equilibrium parameters implied that irrespective of surface functionality the adsorption process is spontaneous and exothermic. Pseudo-second-order rate kinetic model is more appropriate to explain the adsorption kinetics.
ARTICLE | doi:10.20944/preprints201805.0217.v1
Subject: Engineering, Civil Engineering Keywords: Layered double hydroxides; Hydrotalcite; Starch; Fluoride; Adsorption property; Thermodynamics
Online: 15 May 2018 (11:39:28 CEST)
A novel starch stabilized Mg/Al LDHs material (S-LDH) was prepared in a facile approach and its fluoride ion removal performance was developed. Characterization of S-LDH was employed by using XRD, FTIR and particle size distribution. The adsorption property was studied through the assessment of adsorption isotherms, kinetic models, thermal dynamics and pH influence. The result shows that a low loading of starch of 10 mg onto LDH could obviously improve fluoride removal rate. The S-LDH had 3 times higher adsorption capacity to fluoride than that of Mg/Al LDH to fluoride. The particle size was smaller and the particle size distribution was narrower for S-LDH than that for Mg/Al LDH. Langmuir adsorption isotherm model and pseudo-second-order kinetic model fitted well with the experimental data. In thermodynamic parameters, the enthalpy (△H0) value was 35.63 kJ mol-1 and the entropy (△S0) value was 0.0806 kJ mol-1K-1. The values of △G0 were negative, implying the adsorption process is spontaneous. S-LDH reveals stable adsorption property in a wide pH range from 3 to 9. The mechanism for fluoride adsorption on S-LDH included surface adsorption and interaction ion exchange.
ARTICLE | doi:10.20944/preprints202205.0200.v1
Subject: Life Sciences, Biophysics Keywords: membrane potential; Nernst equation; ion adsorption; surface charge; surface potential
Online: 16 May 2022 (08:12:52 CEST)
Although there is a common physiological notion that the origin of the membrane potential is attributed to transmembrane ion transport, it is theoretically possible to explain its generation by the mechanism of ion adsorption. It was previously suggested that the ion adsorption mechanism led even to the potential formulas which are even identical to either the famous Nernst equation or Goldman-Hodgkin-Katz equation. Our further analysis shown in this paper indicates that the potential formula based on the ion adsorption mechanism leads to one equation which is the function of material surface charge density and the material surface potential. Furthermore, we confirmed that the equation holds in all the different experimental systems we studied. Although we have not succeeded in elucidating why such an equation is established, the equation appears to be the key equation governing the characteristics of the membrane potential regardless of the systems in question.
ARTICLE | doi:10.20944/preprints202204.0038.v1
Subject: Biology, Physiology Keywords: Goldman-Hodgkin-Katz eq.; Nernst eq.; ion adsorption; membrane potential
Online: 6 April 2022 (08:37:53 CEST)
Current physiology attributes the mechanism of membrane potential generation to transmembrane ion transport, but ion adsorption could just as well play this fundamental role. The evidence shows that the ion adsorption mechanism accurately reproduces the experimentally measured membrane potential. The Goldman-Hodgkin-Katz equation (GHK eq.) and the Nernst equation (Nernst eq.) are the typical mathematical formulas representing the membrane potential in current physiology. However, the authors were able to show that the potential formulas by ion adsorption mechanism give identical results to GHK eq. and Nernst. eq. Our experimental and theoretical analyses suggest that there is a special relationship between the membrane potential and the membrane surface charge density, and this unique equation inevitably leads to the establishment of a GHK eq and/or a Nernst eq. The authors found that the unique equation is the foundation of thermodynamics “Boltzmann distribution”. Thus, the GHK eq. and the Nernst eq. are simply the natural consequence of thermodynamics from the view of the ion adsorption mechanism.
ARTICLE | doi:10.20944/preprints202110.0138.v1
Subject: Materials Science, Nanotechnology Keywords: α- Fe2O3; hematite; gelatin; f-127; hexagonal-flake; adsorption; ibuprofen
Online: 8 October 2021 (11:17:24 CEST)
Hematite (-Fe2O3) with uniform hexagonal flakes morphology has been successfully synthesized using a combination of gelatin as natural template with F127 via hydrothermal method. The resulting hematite was investigated as adsorbent and photocatalyst for removal of ibuprofen as pharmaceutical waste. Hexagonal flake-like hematite was obtained following calcination at 500 oC with the average size was measured at 1-3 µm. Increasing the calcination temperature to 700 oC transformed the uniform hexagonal structure into cubic shape morphology. Hematite also showed high thermal stability with increasing the calcination temperatures, however, the surface area was reduced from 47 m2/g to 9 m2/g. FTIR analysis further confirmed the formation Fe-O-Fe bonds, and the main constituent elements of Fe and O were observed in EDX analysis for all samples. Fe2O3-G samples have an average adsorption capacity of 55-25.5 mg/g at 12-22% of removal efficiency when used as adsorbent for ibuprofen. The adsorption capacity was reduced with increasing the calcination temperatures due to the reduction of available surface area of the hexagonal flakes when transformed into cube. Photocatalytic degradation of ibuprofen using hematite flakes achieved 50% of removal efficiency meanwhile combination of adsorption and photocatalytic degradation further removed 80% of ibuprofen in water/hexane mixtures.
ARTICLE | doi:10.20944/preprints202107.0395.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Melatonin; molecular modelling; adsorption; clays; modified drug release; molecular dynamics
Online: 19 July 2021 (08:44:04 CEST)
Melatonin is a hormone used for treating several disorders. However, its oral administration is problematic due to the variable absorption and extensive first-pass metabolism. The topical application of this drug does not present these disadvantages and can be used for therapeutic and skin protection purposes. The adsorption and release of melatonin in the montmorillonite clay was investigated experimentally and theoretically. The drug-clay interaction products were prepared and characterized, showing a modified and improved diffusion and release of melatonin. The crystal structure and spectroscopic properties of melatonin and melatonin-water-mineral materials were studied by molecular modeling, finding that the adsorption of this drug is energetically favourable, and the results were consistent with the experimental data. Ab initio molecular dynamics simulations with the metadynamics methodology showed the release of melatonin from the confined interlayer nanospace of montmorillonite to the liquid bulk water with a 20 kcal/mol free energy barrier.
ARTICLE | doi:10.20944/preprints202103.0541.v1
Subject: Chemistry, Analytical Chemistry Keywords: α-Amylase inhibition; Tannic acid; Mixing order; Binding interactions; Adsorption
Online: 22 March 2021 (15:35:35 CET)
The effects of mixing orders of tannic acid (TA), starch and α-amylase on the enzyme inhibition of TA were studied, including mixing TA with α-amylase before starch addition (order 1), mixing TA with pre-gelatinized starch before α-amylase addition (order 2) and co-gelatinizing TA with starch before α-amylase addition (order 3). It was found that the enzyme inhibition was always highest for order 1 because TA could bind with the enzyme active site thoroughly before digestion occurred. Both order 2 and 3 reduced α-amylase inhibition through decreasing binding of TA with the enzyme, which resulted from the non-covalent physical adsorption of TA with gelatinized starch. Interestingly, at low TA concentration, α-amylase inhibition for order 2 was higher than order 3, while at high TA concentration, the inhibition was shown with opposite trend, which arose from the difference in the adsorption property between the pre-gelatinized and co-gelatinized starch at the corresponding TA concentrations. Besides, both the crystalline structures and apparent morphology of starch were not significantly altered by TA addition for order 2 and 3. Conclusively, although a polyphenol may have an acceptable inhibitory activity in vitro, the actual effect may not reach the expected one when taking processing procedures into account.
Subject: Chemistry, Analytical Chemistry Keywords: CO2 capture; adsorption; amine-based adsorbents; mesoporous carbon; triethylenetetramine; ethylenediamine
Online: 3 March 2021 (14:16:48 CET)
Carbon sequestration via carbon capture and storage (CCS) method is one of the most useful methods to lower the CO2 emission in the atmosphere. Ethylenediamine (EDA) and triethylenetetramine (TETA) modified mesoporous carbon (MC) has been successfully prepared as CO2 storage materials. The effect of various concentrations of EDA or TETA added to MC as well as activated carbon (AC) on their CO2 adsorption capacity were investigated using high purity CO2 as feed and titration method to quantitatively measure the amount of adsorbed CO2. The results showed that within 60 min adsorption time, MCEDA49 gave the highest CO2 capacity adsorption (19.68 mmol/g), followed by MC-TETA30 (11.241 mol/g). The improvement of CO2 adsorption capacity at low TETA loadings proved that the four amine functional groups in TETA gave advantages to CO2 adsorption. TETA functionalized MC has a potential to be used as CO2 storage materials as it is used at low concentration. Therefore, it is more benign and friendly to the environment.
ARTICLE | doi:10.20944/preprints202009.0562.v1
Subject: Materials Science, Biomaterials Keywords: adsorption; graphene oxide; methylene blue; pharmaceuticals; kinetics, isotherms and thermodynamics
Online: 24 September 2020 (04:27:52 CEST)
The remarkable adsorption capacity of graphene derived materials has prompted their examination in composite materials suitable for deployment in treatment of contaminated waters. In this study, crosslinked calcium alginate – graphene oxide beads were prepared and activated by exposure to pH 4 by using 0.1M HCl. The activated beads were investigated as novel adsorbents for the removal of organic pollutants (Methylene Blue dye and the pharmaceuticals Famotidine and Diclofenac) with a range of physicochemical properties. Effects of initial pollutant concentration, temperature, pH and adsorbent dose were investigated and kinetic models were examined for fit to the data. Maximum adsorption capacities qmax obtained were 1334, 35.50 and 36.35 mg g-1 for the uptake of Methylene blue, Famotidine and Diclofenac respectively. The equilibrium adsorption had an alignment with Langmuir isotherms while the kinetics were most accurately modelled using a pseudo- first –order and second order models according to the regression analysis. Thermodynamic parameters such as ΔG◦, ΔH◦ and ΔS◦ were calculated and the adsorption process was determined to be exothermic and spontaneous.
ARTICLE | doi:10.20944/preprints201909.0286.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: pd doped graphyne; dissolved gases; adsorption; density functional theory (dft)
Online: 25 September 2019 (16:01:58 CEST)
To realize high response and selectivity gas sensor in detecting dissolved gases in transformer oil, in this study, the adsorption of four kinds of gases (H2, CO, C2H2 and CH4) on Pd-graphyne as well as the gas sensing properties evaluation were investigated. The energetically favorable structure of Pd doped γ-Graphyne was first studied, including the comparison of different adsorption sites and discussion of electronic properties. Then, the adsorption of these four molecules on Pd-graphyne was explored. The adsorption structure, adsorption energy, electron transfer and electron distribution, the band structure and density of states were calculated and analyzed. The results show that the Pd atom prefers to be adsorbed on the middle of three C≡C bonds and the band gap is smaller. The CO adsorption exhibits the largest adsorption energy and electron transfer and brings obvious change to the structure and electron properties to Pd-graphyne. Because of the conductance decrease after adsorption CO and acceptable recovery time at high temperature, the Pd-graphyne can be promising gas sensing materials to detect CO with high selectivity. This work offers theoretical support for the design of nanomaterials based gas sensor using novel structure for industrial application.
ARTICLE | doi:10.20944/preprints201908.0134.v1
Subject: Chemistry, Electrochemistry Keywords: aluminium alloy; corrosion inhibitor; alkaline environment; impedance analysis; adsorption; dihydroxybenzene
Online: 12 August 2019 (03:58:57 CEST)
Selection of efficient corrosion inhibitors requires detailed knowledge regarding interaction mechanism, which depends on the type and amount of functional groups within the inhibitor molecule. Position of functional groups between different isomers is often overlooked but not less important since factors like steric hinderance may significantly affect the adsorption mechanism. In this study we have presented how different dihydroxybenzene isomers interact with aluminium alloy 5754 surface, reducing its corrosion rate in bicarbonate buffer (pH = 11). We have shown the highest inhibition efficiency among tested compounds belongs to catechol at 10 mM concentration, although differences were moderate. Utilization of novel impedance approach to adsorption isotherm determination allowed to confirm that while resorcinol chemisorbs on aluminium surface, catechol and quinol follows ligand exchange model of adsorption. Unlike catechol and quinol, the protection mechanism of resorcinol is bound to interaction with insoluble aluminium corrosion products layer and was only found efficient at concentration of 100 mM (98.7%). The aforementioned studies were confirmed with scanning electron microscopy and x-ray photoelectron spectroscopy analyses. There is a significant increase of the corrosion resistance offered by catechol at 10 mM after 24 h exposure in electrolyte: from 63 to 98%, with only negligible changes in inhibitor efficiency observed for resorcinol at the same time. However, in the case of resorcinol a change in electrolyte color was observed. We have revealed that the differentiating factor is the keto-enol tautomerism. The NMR studies of resorcinol indicate the keto form in structure in presence of NaOH, while the chemical structure of catechol does not change significantly in alkaline environment.
ARTICLE | doi:10.20944/preprints201807.0418.v1
Subject: Materials Science, Nanotechnology Keywords: graphitic carbon spheres; catalytic graphitization; hierarchical pores; supercapacitors; dye adsorption
Online: 23 July 2018 (11:47:13 CEST)
Hierarchical micro-/mesoporous graphitic carbon spheres (HGCS) with a uniform diameter of ~0.35 μm were synthesized by Fe-catalyzed graphitization of amorphous carbon spheres resultant from hydrothermal carbonization. The HGCS resultant from 3 h at 900 °C with 1.0 wt% Fe catalyst had high graphitization degree and surface area as high as 564 m2/g. They also exhibited high specific capacitance of 140 F/g at 0.2 A/g, good electrochemical stability with 94% capacitance retention after consecutive 2500 cycles. The graphitization degree of the HGCS contributed about 60% of their specific capacitance, and their specific capacitance per unit surface area was as high as 0.2 F/m2 which was much higher than in the most cases of porous amorphous carbon materials reported before. In addition, the HGCS showed a high adsorption capacity of 182.8 mg/g for methylene blue (MB), which was 12 times as high as that in the case of carbon spheres before graphitization.
REVIEW | doi:10.20944/preprints201806.0385.v1
Subject: Engineering, Mechanical Engineering Keywords: adsorption; heat storage; thermo-chemical; zeolite; silica gel; adsorbent materials
Online: 25 June 2018 (11:56:14 CEST)
Thermal energy storage (TES) is a key technology to enhance the efficiency of energy systems as well as to increase the share of renewable energies. In this context, the present paper reports a literature review of the recent advancement in the field of adsorption TES systems. After a first introduction about different heat storage technologies, the adsorption TES working principle is explained and compared to the other technologies. Subsequently, promising features and critical issues at material, component and system levels are deeply analyzed and the ongoing activities to make this technology ready for marketing are introduced.
ARTICLE | doi:10.20944/preprints201608.0189.v1
Subject: Chemistry, Physical Chemistry Keywords: amine-modified MCM-41; CO2 adsorption; inorganic alkali; alkali amounts
Online: 22 August 2016 (05:47:02 CEST)
Three kinds of inorganic alkali are introduced into tetraethylenepentamine (TPEA) and polyethyleneimine (PEI) modified MCM-41 as the CO2 adsorbents. FT-IR and TGA are used to characterize the surface groups and the thermal stability of adsorbents. Chemical titration method is used to measure the alkali amounts of adsorbents. Thermo-gravimetric analysis with 10%CO2/N2 as the simulated flue gas is used to test the CO2 adsorption performance of adsorbents. The results show that all three kinds of inorganic alkali containing adsorbents exhibit promoted CO2 adsorption capability than traditional TPEA and PEI modified samples. Ca(OH)2 and PEI modified samples exhibit the highest adsorption capacity and stable regeneration property. The introduction of inorganic alkali changes the chemical adsorption mechanism between CO2 and increases the effective alkali amounts due to its hydroxyl groups. The CO2 adsorption capacities have a linear dependence relation with the alkali amounts of adsorbents, indicating that alkali amount is a critical factor for novel adsorbents exploring.
ARTICLE | doi:10.20944/preprints202212.0434.v1
Subject: Chemistry, Analytical Chemistry Keywords: Adsorption; β-agonists; Magnetic-composite; Metal-Organic Frameworks; Pollutant; Removal; Terbutaline
Online: 23 December 2022 (01:51:10 CET)
Mechanochemical production of copper (II) isonicotinate Metal-Organic Framework ([Cu (INA)2]-MOF) and its modified magnetic iron composite ([Cu (INA)2]-MOF@Fe3O4]) allowed for the adsorptive removal of Terbutaline from water. A variety of characterization techniques, including Fourier, transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM), were used to elucidate the distinct chemical and morphological features of the two advanced materials. The optimal adsorption conditions were determined by investigating a wide range of adsorption-related variables, including contact time, initial Terbutaline concentration, adsorbent dosages pH, and temperature. The chemistry involved in the adsorption process between the adsorbents and the adsorbate molecules was evaluated using the best-fitting models, such as kinetics, isotherms, and thermodynamics, and the regeneration study was performed to evaluate the adsorbents' reusability. Incredibly maximum adsorption capacities (Qmax) of 1667 and 2500 mg L-1 were attained within 40 minutes under alkaline pH 11 by the [Cu (INA)2]-MOF and the [Cu (INA)2]-MOF@Fe3O4, respectively. The adsorbents have been proven to be good for the adsorption of Terbutaline as a priority pollutant in an aqueous solution, with pseudo-first order and Langmuir as the best-fitting models for the kinetic and isotherm models respectively.
ARTICLE | doi:10.20944/preprints202205.0369.v1
Subject: Earth Sciences, Environmental Sciences Keywords: carbamazepine; adsorption; clay minerals; organoclays; advanced oxidation processes; photocatalysis; water reuse
Online: 27 May 2022 (04:42:22 CEST)
Carbamazepine (CBZ) is one of the most common emerging contaminants released to the aquatic environment through domestic and pharmaceutical wastewater. Due to its high persistence through conventional degradation treatments, is considered a typical indicator for anthropogenic activities. This study tested the removal of CBZ through two different clay-based purification techniques: adsorption of relatively large concentrations (20-500 μmol L-1) and photocatalysis of lower concentrations (<20 μmol L-1). The sorption mechanism was examined by FTIR measurements, exchangeable cations released, and colloidal charge of the adsorbing clay materials. Photocatalysis was performed in batch experiments under various conditions. Despite the neutral charge of carbamazepine, the highest adsorption was observed on negatively charged montmorillonite-based clays. Desorption tests indicate that adsorbed CBZ is not released by washing. The adsorption/desorption processes were confirmed by ATR-FTIR analysis of the clay-CBZ particles. A combination of synthetic montmorillonite or hectorite with low H2O2 concentrations under UVC irradiation exhibits efficient homo-heterogeneous photodegradation at μM CBZ levels. The two techniques presented in this study suggest solutions for both industrial and municipal wastewater, possibly enabling water reuse.
ARTICLE | doi:10.20944/preprints202204.0049.v1
Subject: Materials Science, Biomaterials Keywords: L-asparaginase; Enzyme immobilization; Carbon xerogels; Physical adsorption; Central Composite Design
Online: 6 April 2022 (13:49:49 CEST)
L-asparaginase (ASNase) is an aminohydrolase currently used in the pharmaceutical and food industries. Enzyme immobilization is an exciting option for both applications, allowing a more straightforward recovery and increased stability. High surface area and customizable porosity make carbon xerogels (CXs) promising materials for ASNase immobilization. This work describes the influence of contact time, pH, and ASNase concentration on the immobilization yield (IY) and relative recovered activity (RRA) using Central Composite Design methodology. The most promising results were obtained using CX with an average pore size of 4 nm (CX-4), reaching IY and RRA of 100%. At the optimal conditions, the ASNase-CXs biocomposite was characterized and evaluated in terms of kinetic properties and operational, thermal and pH stabilities. The immobilized ASNase onto CX-4 retained 71% of its original activity after six continuous reaction cycles, showed a good thermal stability at 37 °C (RRA of 91% after 90 min) and was able to adapt to both acidic and alkaline environments. Finally, the results indicated a 3.9-fold increase in the immobilized ASNase affinity for the substrate, confirming the potential of CXs as a support for ASNase and as a cost-effective tool for subsequent use in the therapeutic and food sectors.
Subject: Keywords: membrane theory; Association-Induction Hypothesis; ion transport, ion adsorption; membrane potential
Online: 13 August 2021 (08:53:04 CEST)
Accurate prediction of the membrane potential by membrane theory is possible on the basis that the plasma membrane is selectively permeable to ions and that permeability determines the characteristics of the membrane potential. However, an experimental and artificial cell system with an impermeable membrane serving as a model plasma membrane has a non-zero membrane potential, and this potential generated across the membrane is somehow consistent with the potential characteristics predicted by the membrane theory, despite the impermeability of the membrane to ions. A long-forgotten theory, called the association-induction hypothesis (AIH), has emerged as a more plausible mechanism for generating the membrane potential than the membrane theory to explain this unexpected behavior. The AIH asserts that ion-selective membrane permeability is not necessary for the generation of the membrane potential, which is contrary to the membrane theory. Although such an idea is not easy to accept, the experimental results clearly suggest the correctness of the AIH.
ARTICLE | doi:10.20944/preprints202101.0352.v1
Subject: Earth Sciences, Environmental Sciences Keywords: adsorption; astrobiology; chemical evolution; origin of life; polymerization; surface complexation modeling
Online: 18 January 2021 (15:01:36 CET)
The ubiquity of amino acids in carbonaceous meteorites has suggested that amino acids are widespread in the Universe, serving as a common class of components for the emergence of life. However, parameters for modeling amino acid polymerization at mineral–water interfaces remain limited, although the interfacial conditions inevitably exist on planets with surface liquid water. Here, we present a set of extended triple-layer model parameters for aspartate (Asp) and aspartyl-aspartate (AspAsp) adsorptions on ferrihydrite, anatase, and γ-alumina determined based on the experimental adsorption data. By combining the parameters with the reported thermodynamic constants for amino acid polymerization in water, the impacts of these minerals on Asp dimerization are calculable over a wide range of environmental conditions. It was predicted, for example, that ferrihydrite strongly increases the AspAsp/Asp equilibrium ratio in neutral to acidic pH; the ratio in the adsorbed state reaches 40% even from a low Asp concentration (0.1 mM) at pH 4. This percentage is approximately 5 × 107 times higher than that attainable without mineral (8.5 × 10–6%). Our exemplified approach enables us to screen wide environmental settings for abiotic peptide synthesis from a thermodynamic perspective, thereby narrowing down the geochemical situations to be explored for life’s origin on Earth and Earth-like habitable planets.
REVIEW | doi:10.20944/preprints201807.0242.v1
Subject: Materials Science, General Materials Science Keywords: Metal-organic frameworks; heat transformation; low temperature heat; adsorbent; water adsorption.
Online: 13 July 2018 (15:32:52 CEST)
Metal-Organic Frameworks (MOFs) are a subclass of porous materials that have unique properties such as varieties of structures from different metals and organic linkers, tunable porosity from a structure or framework design, etc. Moreover, modification/functionalization of the material structure could optimize the material properties and demonstrate high potential for a selected application. MOF materials exhibit exceptional properties and make these materials widely applicable including in energy storage and heat transformation applications. This review aims to give a broad overview of MOFs and their development as adsorbent materials having the potential for heat transformation applications. We summarize current investigations, developments, and possibilities of metal-organic frameworks (MOFs) especially the tuning of the porosity and hydrophobic/hydrophilic design required for this specific application. These materials applied as adsorbent are promising in the thermal driven adsorption for heat transformation using water as working fluid and related application.
ARTICLE | doi:10.20944/preprints201806.0260.v1
Subject: Chemistry, Physical Chemistry Keywords: ATRP; chitosan grafted poly acrylic acid; heavy metals; adsorption; water treatment.
Online: 15 June 2018 (14:50:41 CEST)
In this work, we synthesized chitosan grafted-poly acrylic acid (CS-g-PA) through surface-initiated atom transfer radical polymerization (SI-ATRP). We also studied the adsorption process of copper and lead ions onto CS-g-PA surface. Adsorption equilibrium studies indicated pH 4.0 as the best pH for the adsorption process, while the maximum adsorption capacity for Pb2+ ions was 98 mg*g-1 and for Cu2+ was 164 mg*g-1, higher adsorption capacities than chitosan alone (CS), where Pb2+ was only 14.8 mg*g-1and Cu2+ was 140 mg*g-1, respectively. Furthermore, the adsorption studies indicated that Langmuir model describes all the experimental data. All these results suggest that the new CS-g-PA polymers had potential as adsorbent for hazardous and toxic metal ions produced by different industries.
ARTICLE | doi:10.20944/preprints201612.0100.v1
Subject: Earth Sciences, Environmental Sciences Keywords: engineering barriers; bentonite clays; thermochemical treatments; montmorillonite; structure modification; adsorption properties
Online: 19 December 2016 (11:08:23 CET)
The paper discusses the mechanism of montmorillonite structure alteration and bentonites properties modification (on the example of samples from clay deposit Taganka, Kazakhstan) due to the thermochemical treatment (treatment with inorganic acid solutions at different temperatures, concentrations and reaction times). With the use of the suit of methods certain processes were distinguished: transformation of montmorillonite structure, which appears in the leaching of interlayer and octahedral cations, protonation of the interlayer and OH groups at octahedral sheets. Changes in the structure of the 2:1 layer of montmorillonite and its interlayer result in significant changes in the properties – reduction of cation exchange capacity and an increase of specific surface area. The results of the work showed that bentonite clays retain a significant portion of its adsorption properties even after the long term and intense thermochemical treatment (6M HNO3, 60°C, 108 hours)
ARTICLE | doi:10.20944/preprints202301.0154.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Amine functionalized MWCNTs; Reactive yellow 2; Adsorption; Rapid removal; Ionic strength; Reusability
Online: 9 January 2023 (09:02:49 CET)
This research intended to report amine-functionalized multiwall carbon nanotubes (MWCNTs) prepared by a simple method for efficient and rapid removal of Reactive Yellow 2 (RY2) from water. EDS analysis showed that the N content increased from 0 to 2.42% and from 2.42 to 8.66% after modification by APTES and PEI, respectively. BET analysis displayed that the specific surface area, average pore size, and total pore volume were reduced from 405.22 to 176.16 m2/g, 39.67 to 6.30 nm, and 4.02 to 0.28 cm3/g, respectively. These results proved that the PEI/APTES-MWCNTs were successfully prepared. pH edge experiment indicated that pH 2 was optimal for RY2 removal. At pH 2 and 25 °C, the time required for adsorption equilibrium was 10, 15, and 180 min at initial concentrations of 50, 100, and 200 mg/L, respectively; and the maximum RY2 uptake calculated by the Langmuir model was 714.29 mg/g. Thermodynamic studies revealed that the adsorption process was spontaneous and endothermic. 0-0.1 mol/L of NaCl showed negligible effect on RY2 removal by PEI/APTES-MWCNTs. Five adsorption/desorption cycles confirmed the good reusability of PEI/APTES-MWCNTs in RY2 removal. Overall, the PEI/APTES-MWCNTs are a potential and efficient adsorbent for reactive dye wastewater treatment.
ARTICLE | doi:10.20944/preprints202112.0308.v1
Subject: Physical Sciences, Other Keywords: Nano-ZrO2+3 mol.%Y2O3; Hydrogen generation; Kinetics; Thermal processes; Adsorption, Desorption.
Online: 20 December 2021 (10:50:44 CET)
The physicalchemistry properties and crystal structure of were nano-ZrO2+3mol.%Y2O3 determined. The kinetics of the formation of H2 as a result of the decomposition of H2O on the surface of nano-ZrO2+3mol.%Y2O3 was studied. Effects of adsorption and desorption process on ZrO2+3 mol.%Y2O3 nanoparticles were studied at different (T=400÷10000C) temperature. The study of H2 in thermal processes at nano-ZrO2+3 mol.%Y2O3 system increased. Such an increase in H2 generation in comparison with a pure H2O as thermal processes had formedactive centers for H2O decomposition on the surface of the catalyst at the expense of δ-electrons emitted on the surface of nano-ZrO2+3 mol.%Y2O3. This showed that the dimensions of the studied nanoscale particles systems are comparable to the free running distance of energy carriers generated by of nano-ZrO2+3 mol.%Y2O3 as a result of thermal processes. These results are promising for hydrogen generation by waer spliting in near future.
ARTICLE | doi:10.20944/preprints202106.0485.v1
Subject: Engineering, Civil Engineering Keywords: Metal Organic Framework; Cu (II) ion- industrial waste water; pH; time; adsorption
Online: 18 June 2021 (15:16:57 CEST)
Copper is a heavy metal used in many industries and known for its negative impacts on the environment and human’s health. A novel structured metal organic framework (MOF) was used for copper adsorption for this work. SEM, EDAX, XRD and FTIR were done to confirm the structure of MOF prepared. MOF of 0.05 gm was used to examine its ability in Cu+ 2 removals with different initial concentrations of Cu+2 and pH values (5, 7 and 9). The prepared MOF was able to achieve Cu removal with 94.6%, 93%, 91.5%, and 92.5 % for the initial concentrations of 5, 10, 15, and 20 ppm respectively. It also performed very well for pH 5 and 7 with average removal ranging from 93.9%-95% for pH 5 and 7 for the initial concentrations of 5, 10, and 15 respectively which indicate that the prepared MOF is of high ability in Cu+ 2 removal.
ARTICLE | doi:10.20944/preprints202102.0171.v1
Subject: Chemistry, General & Theoretical Chemistry Keywords: P–fertility, orthophosphate, glycerolphosphate, inositolhexaphosphate, goethite, adsorption, surface complexation, MD simulations, QMMM
Online: 8 February 2021 (07:43:53 CET)
Knowledge of the interaction between inorganic and organic phosphates with soil minerals is vital for improving the soil P fertility. To achieve an in-depth understanding we combined adsorption experiments and hybrid ab initio molecular dynamics simulations to analyze the adsorption of common phosphates, i.e. orthophosphate (OP), glycerolphosphate (GP) and inositolhexaphosphate (IHP), onto the 100 surface plane of goethite. Experimental adsorption data per mol P-molecule basis fitted to the Freundlich model show the adsorption strength increases in the order GP < OP < IHP, and IHP adsorption being saturated faster followed by GP and OP. Modeling results show that OP and GP form stable monodentate (M) and binuclear bidentate (B) motifs with B being more stable than M, whereas IHP forms stable M and 3M motifs. Interfacial water plays an important role through hydrogen bonds and proton transfers with OP/GP/IHP and goethite. It also controls the binding motifs of phosphates with goethite. Combining both experimental and modeling results, we propose that the B motif dominates for OP, whereas GP forms M and IHP forms a combination of M and 3M motifs. The joint approach plausibly explains why IHP is the predominant organically bound P form in soil. This study could be considered as a preliminary step for further studies for understanding the mechanisms of how microbes and plants overcome the strong IHP–mineral binding to implement the phosphate groups into their metabolism.
ARTICLE | doi:10.20944/preprints201908.0093.v2
Subject: Chemistry, Food Chemistry Keywords: spent coffee grounds; polyphenols; extraction; subcritical fluid; activated carbon; methylene blue; adsorption.
Online: 20 September 2019 (10:23:51 CEST)
A valorization process of spent coffee grounds (SCG) was studied. Thus, a two-stage process, a stage of extraction of the polyphenols and a stage of obtaining activated carbon (AC) by a carbonization process, was performed. The extraction was carried out with a hydro-alcoholic solution in a pressure reactor, modifying time and temperature. To optimize the extraction of polyphenols, a two-level factorial design with three replications at the central values was used. The best results were obtained by performing the extraction at 80 °C during 30 min, using a mixture of EtOH:H2O 1:1 (v/v) as extraction solution. Caffeine and chlorogenic acid were the most abundant compounds in the analyzed extracts, ranging from 0.09 to 4.8 mg∙g-1 and 0.06 to 9.7 mg∙g-1, respectively. The precursor obtained in the extraction stage were transformed into AC. An experimental design was realized in order to analyze the influence of different variables in the AC obtained process (reaction time and amount of potassium hydroxide used). Actived carbons with BET specific surface (SBET) comprised between 1600 m2∙g-1 and 2330 m2∙g-1 had a microporous surface. Under the optimum conditions, the obtained AC presented a maximum adsorption capacity of methylene blue (qm) between 411 mg∙g-1 and 813 mg∙g-1.
ARTICLE | doi:10.20944/preprints201809.0605.v2
Subject: Materials Science, Nanotechnology Keywords: adsorption; 3-Aminopropyltriethoxysilane; carbon dioxide; functionalization; mesoporous silica; MCM-41; SBA-15
Online: 27 December 2018 (05:28:16 CET)
The adsorption of carbon dioxide on amino silanes-functionalized MCM-41 and SBA-15 materials is reported. The functionalization of mesoporous silicas was made by post-synthesis method, by impregnation of 3-aminopropyltriethoxysilane. The obtained materials were characterized by X-ray diffraction, scanning and transmission electron microscopies, nitrogen adsorption-desorption and X-ray photoelectron spectroscopy measurements. The carbon dioxide adsorption capacities for the samples were carried out under ambient pressures. The obtained results evidenced that amino-silanes with a terminal amine (–NH2) were functionalized through covalent coupling of this group on the surface of the channels in the ordered mesoporous silica, meaning that the amine is anchored on the surface of the bigger pores of the MCM-41 and SBA-15 support. For functionalized materials, the CO2 adsorption capacity of the AMCM-41 increased from 0.18 to 1.1 mmol·g−1, whereas for ASBA-15, it was from 0.6 to 1.8 mmol·g−1. The Lagergren kinetic algorithms were applied in order to validate the obtained results, evidencing the enhanced carbon dioxide adsorption capacity and stability of the functionalized ordered mesoporous molecular sieves.
ARTICLE | doi:10.20944/preprints201808.0305.v1
Subject: Life Sciences, Microbiology Keywords: Ostreococcus tauri; Mamiellophyceae; Phycodnaviridae; resistance; karyotype; rearrangement; chromosome; specificity; host range; adsorption
Online: 17 August 2018 (12:26:51 CEST)
Prasinoviruses are large dsDNA viruses commonly found in aquatic systems worldwide, where they can infect and lyse unicellular prasinophyte algae such as Ostreococcus. Host susceptibility is virus strain-specific, but resistance of susceptible Ostreococcus tauri strains to a virulent virus arises frequently. In clonal resistant lines that re-grow, viruses are usually present for many generations, and genes clustered on chromosome 19 show physical rearrangements and differential expression. Here, we investigated changes occurring during the first two weeks after inoculation of viruses. By serial dilutions of cultures at the time of inoculation, we estimated the frequency of resistant cells arising in virus-challenged O. tauri cultures to be 10−3–10−4 of the inoculated population. Re-growing resistant cells were detectable by flow cytometry 3 days post-inoculation (dpi), visible re-greening of cultures occurred by 6 dpi, and karyotypic changes were visually detectable at 8 dpi. Resistant cell lines showed a modified spectrum of host-virus specificities and much lower levels of OtV5 adsorption.
ARTICLE | doi:10.20944/preprints201806.0128.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: biogas purification; coconut shells; biomass valorization; textural characterization; adsorption isotherms; breakthrough curves.
Online: 7 June 2018 (16:27:12 CEST)
Biomass is a widely distributed and renewable source of carbon. The main objective of this work is to produce an activated carbon from coconut shells with suitable characteristics to separate CO2 from biogas. The textural characterization of the adsorbent has been determined. Pure component adsorption isotherms of CO2 and CH4 at 30, 50 and 70 °C have been measured. Moreover, the performance of the produced activated carbon, as potential adsorbent for CO2 capture from a CO2/CH4 gas mixture has been evaluated under dynamic conditions in a purpose-built fixed-bed setup.
ARTICLE | doi:10.20944/preprints202010.0627.v1
Subject: Chemistry, Analytical Chemistry Keywords: activated carbon; winemaking waste; wastewater; Cr(VI) removal; adsorption process; Cr(VI) reduction
Online: 30 October 2020 (08:28:29 CET)
A winemaking waste was used as a precursor of activated carbon used in hazardous Cr(VI) removal from solutions. The preparation process consisted of a hydrothermal process, and a chemical activation, of the resulting product, with KOH. The adsorption results showed that the adsorption of Cr(VI) on the obtained activated carbon is strongly dependent on the stirring speed applied to the carbon/solution mixture, pH of the solution, and temperature. The equilibrium isotherm was well fitted to the Langmuir type-II equation, whereas the kinetic can be described by the pseudo-second-order kinetic model. Thermodynamic studies revealed that Cr(VI) adsorption was an exothermic and spontaneous process. Finally, desorption experiments showed that Cr(VI) was effectively desorbed using hydrazine sulfate solutions, and at the same time, the element was reduced to the less hazardous Cr(III) oxidation state.
ARTICLE | doi:10.20944/preprints201910.0344.v1
Subject: Materials Science, General Materials Science Keywords: banana empty fruit bunch; TiO2/fibre; adsorption; rhodamine B; isotherm and kinetic adsorptions
Online: 30 October 2019 (02:21:11 CET)
Indonesia is one of the largest banana producing countries in the world remaining abundance solid waste of banana fruit bunch. The banana fruit bunch contains high natural fibers which were obtained by an impregnation process using potassium hydroxide (KOH) and followed by a carbonization process under steam at 250°C for 5 h. The nanomaterial of TiO2/fibre was prepared by a hydrothermal process at 200°C for 4 h. Surface morphology proved that the TiO2 was loaded into the fibre by an increasing roughness of the surface and irregular size of porosity. The development of amorphous to crystalline phase of TiO2/fibre was clearly observed. The effectiveness of TiO2/fibre for removal of rhodamine B was investigated from different parameters of adsorptions in aqueous solution. The equilibrium adsorptions show that the Langmuir and Freundlich isotherm exhibited the best correlation coefficient (R2 > 0.94) relating to the chemisorption and physisorption interaction in the adsorption process. Kinetic models were well described by the pseudo-first and second-order with the best correlation coefficient (R2 > 0.99). These results indicate that nanomaterial TiO2/fibre can be used as an effective adsorbent for removal of rhodamine B in aqueous solution.
ARTICLE | doi:10.20944/preprints201812.0107.v1
Subject: Chemistry, Physical Chemistry Keywords: clay; diazonium salt; ion imprinted polymers; radical photopolymerization; visible light; adsorption; copper ions
Online: 10 December 2018 (14:27:52 CET)
There is an urgent demand worldwide for the development of highly selective adsorbents and sensors of heavy metal ions and other organic pollutants. Within these environmental and public health frameworks, we are combining the salient features of clays and chelatant polymers to design selective metal ion adsorbents. Towards this end, the ion imprinting approach has been used to develop a novel nanohybrid material for the selective separation of Cu2+ ions in aqueous solution. The Cu2+-imprinted polymer/ montmorillonite nanocomposite (IIP/Mt) and non-imprinted polymer/montmorillonite nanocomposite (NIP/Mt) were prepared by radical photopolymerization process in the visible light. Ion imprinting was indeed important as the recognition of copper ions by IIP/Mt was significantly superior to that of NIP/Mt that is the nanocomposite synthesized in the same way but in the absence of Cu2+ ions. The adsorption process as batch study was investigated under the experimental condition affecting same parameters such as contact time, concentration of ions metals and pH. The adsorption capacity of Cu2+ ions is maximized at pH 5. Removal of Cu2+ ion achieved equilibrium within 15 minutes; the results obtained were found to be fitted by the pseudo-second order kinetics model. The equilibrium process was well described by the Langmuir isothermal model and the maximum adsorption capacity was found to be 23.6 mg/g.
ARTICLE | doi:10.20944/preprints201701.0029.v2
Subject: Chemistry, General & Theoretical Chemistry Keywords: electron transfer; Marcus equation; enzymatic fuel cell; hydrogen oxidation; electrode adsorption; DFT; bioelectrochemistry
Online: 9 January 2017 (02:49:00 CET)
Biohydrogen is a versatile energy carrier for the generation of electric energy from renewable sources. Hydrogenases can be used in enzymatic fuel cells to oxidize dihydrogen. The rate of electron transfer (ET) at the anodic side between the [NiFe]-hydrogenase enzyme distal iron-sulfur cluster and the electrode surface can be described by the Marcus equation. All parameters for the Marcus equation are accessible from DFT calculations. The distal cubane FeS-cluster has a three cysteine and one histidine coordination [Fe4S4](His)(Cys)3 first ligation sphere. The reorganization energy (inner- and outer-sphere) is almost unchanged upon a histidine-to-cysteine substitution. Differences in rates of electron transfer between the wild-type enzyme and the all-cysteine mutant can be rationalized by a diminished electronic coupling between the donor and acceptor molecules in the [Fe4S4](Cys)4 case. The fast and efficient electron transfer from the distal iron-sulfur cluster is realized by a fine-tuned protein environment which facilitates the flow of electrons. This study enables the design and control of electron transfer rates and pathways by protein engineering.
ARTICLE | doi:10.20944/preprints202109.0054.v1
Subject: Engineering, Civil Engineering Keywords: Water desalination; Flow-electrode capacitive deionization; Salt removal efficiency (SRE); Salt adsorption capacity (SAC)
Online: 3 September 2021 (10:20:35 CEST)
Population growth and increasing global demand for freshwater have raised a serious challenge for the depleting sources of freshwater in the 21st century. Desalination technologies can be a reliable technique for providing freshwater. Capacitive deionization is one of the innovative desalination methods that has received increasing interest. Flow-electrode capacitive deionization (FCDI) (a new architecture of capacitive deionization) is one of the efficient, cost-effective, and environmentally-friendly desalination methods for freshwater production. In this experimental research, the performance of an FCDI system was investigated and the influence of important parameters such as flow rate of flow-electrodes, electrolyte salt concentration of flow-electrodes, and initial feed water concentration will be assessed on the efficiency of desalination operation. In this study, the flow-electrodes operated in short-circuited closed-cycle operation (SCC) mode, and also the feed water operated similarly to the flow-electrodes in closed-cycle. Moreover, in all the experiments, the salt adsorption capacity (SAC) and salt removal efficiency (SRE) was calculated. Herein, by optimizing the above mentioned parameters, the salt removal efficiency of 83% and a SAC value of 29.12 mg/g dry carbon were achieved in 5 hours.
ARTICLE | doi:10.20944/preprints202010.0187.v1
Subject: Keywords: sodium adsorption ratio; SAR; CROSS, electrical conductivity; specific conductivity; salinity; irrigation; groundwater; water quality
Online: 9 October 2020 (08:45:56 CEST)
Soil water loss by evaporation influences the sodium adsorption ratio (SAR) of irrigation drainage water. Evaporation concentrates sodium and magnesium but calcite precipitation has a more complicated effect on soluble calcium and alkalinity. Here we propose a revised sodicity hazard assessment that quantifies the impact of evaporative water loss and calcite precipitation on drainage water SAR. This paper shows sodicity hazard is determined by the initial composition of irrigation water as originally suggested by previous researchers, and provide a simple, accurate way to identify the potential sodicity hazard of any irrigation water. In particular, the initial equivalent concentration of alkalinity and calcium determine the salinization pathway followed during evaporation. If the irrigation water alkalinity exceeds soluble calcium expressed as equivalent concentrations, drainage water SAR approaches an upper limit determined by the initial relative concentration of sodium and magnesium. If irrigation water alkalinity is less than soluble calcium, drainage water SAR approaches a lower limit determined by the initial calcium, magnesium and sodium. In both cases the SAR is scaled by the square root of the concentration factor √Fc quantifying soil water loss. To assess the impact of evaporation and calcite precipitation on the SAR and test the accuracy of the new sodicity hazard assessment, we evaluated data from previously published lysimeter studies. We plotted water composition boundaries for each source water, comparing these boundaries to the drainage water composition recorded in the lysimeter studies. As salinity increased by evaporation, each drainage water followed a distinct salinization path.
ARTICLE | doi:10.20944/preprints201811.0477.v1
Subject: Materials Science, Other Keywords: Li-Al-OH LDH; mechanochemical preparation; boron adsorption; physical and chemical synergism; competitive adsorbent
Online: 20 November 2018 (04:02:33 CET)
In this study, Li-Al-OH layered double hydroxide (LDH), which was prepared by solvent-free one-step mechanochemical reaction of LiOH and Al(OH)3, was applied to remove boron from aqueous solution. Dry-grinding for 3 h at a rotational speed of 500 rpm, Li/Al molar 1/2 was the optimum condition to prepare highly crystalline of Li-Al LDH phase with no evident impure phases. Two milling products with Li/Al molar ratio at 1/2 and 2/2 were evaluated for boron adsorption. The results confirmed that Li/Al molar ratio 2/2 sample showed high boron adsorption capacity due to the physical adsorption of Li-Al-OH LDH and chemical synergism of phase gel Al(OH)3. The adsorption isotherms, described by the Langmuir model, indicated maximum monolayer boron uptake capacity 45.45 mg/g, implying competitive adsorption capacity of the material in our experiment.
ARTICLE | doi:10.20944/preprints202112.0221.v1
Subject: Earth Sciences, Environmental Sciences Keywords: metal adsorption; soil organic matter; iron oxide; Semi-quantitative analysis method; antagonistic effect; DCB extraction
Online: 14 December 2021 (10:23:18 CET)
The combination of organic matter, iron oxide, and clay minerals is of great significance for the adsorption of copper ions (Cu). The purpose of this study is to explore the characteristics of Cu adsorption and laws governing Cu complexation to organic–inorganic, organic–clay mineral, and iron-oxide–clay mineral complexes in the sediments in the estuary of plateau fault and sinking lake——Dianchi Lake. In this study, Cu adsorption tests were performed on the three complexes, in order to study the kinetic behavior of adsorption, Langmuir and Freundlich isotherm models were used. The samples before and after adsorption were characterized via scanning electron microscope (SEM), Fourier infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Our results show that, the Freundlich isotherm models model was able to describe adsorbent behavior in comparison to the Langmuir models. During the Cu adsorption process, the iron-oxide–clay mineral complex is able to adsorb Cu, via coordination exchange, through the –OH contained therein. Organic-matter–clay mineral complexes bonded to the surfaces of clay minerals by replacing the hydroxyl groups with functional groups (carboxyl groups or phenolic hydroxyl groups) contained in the organic matter. Organic–inorganic composites then adsorbed Cu through the coordination exchange of –OH in the polar functional groups of alcohols, phenols, and carboxylic acids. The adsorption capacity of Cu in these three sediment complexes was observed to have the following order: organic–inorganic complex > organic-matter–clay mineral complex > iron-oxide–clay mineral complex. The semi-quantitative analysis results of Fourier Infrared Spectroscopy show that the organic matter (changes in the peak area of functional groups such as carboxyl groups) in the organic-inorganic composite material has an important effect on the amount of copper ions adsorbed by clay minerals.
ARTICLE | doi:10.20944/preprints202111.0180.v1
Subject: Earth Sciences, Environmental Sciences Keywords: Electrical Conductivity, Sodium Adsorption Ratio, Salinity, Sodicity, Groundwater Chemistry, Surface Water Chemistry, Irrigation Water Quality
Online: 9 November 2021 (14:08:29 CET)
Seyfe Lake is an important part of the natural ecosystem of Central Anatolia and lies within a 1487 km2 closed basin. Groundwater withdrawal for irrigation and recent climatic change have caused lake area to decrease for decades and to completely disappear briefly in August 2008. Groundwater quality is crucial for sustainable irrigation in the Seyfe Basin. A key finding of this study is the difference in the Hardie-Eugster alkalinity-to-calcium ratio of the lake water and that of most groundwater wells in the basin. This difference in the chemical signature of Seyfe Lake and basin groundwater means the evaporative salinization pathway of most groundwater discharged into the lake cannot account for the composition of Seyfe Lake. The ratio of actual evapotranspiration to precipitation will increase under current climate change projections. A second finding, with implications for soil salinization, is that most groundwater in Seyfe Basin has a Hardie-Eugster alkalinity-tocalcium ratio greater than unity, meaning soil alkalization will accompany soil salinization.
ARTICLE | doi:10.20944/preprints202102.0118.v1
Subject: Materials Science, Biomaterials Keywords: Adsorption; Amido black (AB); Central composite design (CCD); Eosin B (EB); MWCNT/ZrO2/Pb-NCs
Online: 3 February 2021 (14:42:15 CET)
This research illustrates modification of multi-walled carbon nanotubes (MWCNT) by ZrO2/Pb to construct nanocomposites (MWCNT/ZrO2/Pb-NCs) by simple precipitation technique and subsequently examine its ability for adsorption of Amido black (AB) and Eosin B (EB) dyes in binary system. The present nanocomposites investigation by FESEM, XRD, FTIR, and EDX analysis, reveal its as-synthesized crystalline nature with cubic morphology and average particle size 30–50 nm. The present nano-adsorbent represent high efficiency for AB and EB adsorption from aqueous solution, while dependency of variables including pH, initial concentration of dyes, contact time and MWCNT/ZrO2/Pb-NCs mass were analyzed by central composite design (CCD). The predicted maximum removal percentage was 95% removal for both dyes is consequence of adjustment of operational conditions at pH of 6.0; 0.05 g MWCNT/ZrO2/Pb-NCs; 15 min stirring at 15 mg L-1 for both dyes. The Langmuir as applicable for representation and description of reveal data of adsorption with adsorption capacity of 15.46 and 16.92 mg g-1 for AB and EB, respectively. Pseudo-first order model owing to its high correlation coefficient and closeness of experimental and theoretical data well represented behavior of corresponding adsorption system. Mechanism examination strongly proof high contribution of external mass transference as the main rate-controlling step. The successful regeneration of MWCNT/ZrO2/Pb-NCs suggested their usefulness in wastewater treatment and its ability of environmental management.
ARTICLE | doi:10.20944/preprints201905.0155.v1
Subject: Engineering, Other Keywords: Green Tuff; Towada stone; calcination; recycle; tile; hydrogen peroxide; radical; ESR; adsorption; formaldehyde, UV; photocatalysis
Online: 13 May 2019 (10:26:06 CEST)
Wasted Green tuff powder produced by cutting Towada stone is recycled as environmental cleaning material. The optimum temperature for green tuff powder calcination to reduce the hydroxyl radical produced in hydrogen peroxide decomposition with ultraviolet light (UV) and no light. The green tuff calcined at 800 °C shows the large decomposition rate of hydrogen peroxide with no UV light when measured by using ESR. With UV light, the optimum temperature for calcinating the green tuff powder in order to reduce hydroxyl radical is also 800 °C. Next, the powder calcined at 800 °C is used to produce the tile by compression and heating, and then the formaldehyde adsorption rate was measured. The green tuff powder calcined at 800 °C showed a high adsorption rate, similar to that of the activated carbon. The tiles formed at 40 MPa and heated st 1100 °C were the strongest and also adsorbed formaldehyde. The adsorbed formaldehyde on the green tuff tile and powder might have a possibility to decompose by photocatalytic.
ARTICLE | doi:10.20944/preprints202111.0417.v2
Subject: Physical Sciences, Other Keywords: nanopowders; zirconium oxide nanoparticles; adsorption phase transition; polymorphism in zirconium dioxide; size effect of structural stabilization
Online: 1 December 2021 (13:07:43 CET)
The present study was aimed at revealing the influence of the mechanical stress induced by water molecules adsorption on the composition of crystalline phases in the ZrO2–3mol%Y2O3-nanoparticles. Three basic methods have been used to determine the phase transition: neutron diffraction, Raman microspectroscopic scanning, and X-ray diffraction. The fact of phase-structural β → α transformation and the simultaneous presence of two polymorphic structural modifications (β is the phase of the tetragonal syngony and α of monoclinic syngony in nanosized particles (9nm)) under normal physical conditions was established by these methods. Satisfactory consistency was achieved between the results obtained using different techniques.
ARTICLE | doi:10.20944/preprints202010.0498.v1
Subject: Materials Science, Biomaterials Keywords: HCO-doped-(Fe3O4)x adsorbent; Sb(III) and Sb(V); Ce/Fe molar ratio; Adsorption mechanism
Online: 23 October 2020 (16:41:56 CEST)
Concern over potential antimony mediated toxicity from mining and smelting activities has instigated novel concepts toward removing aqueous antimony ions. The iron based adsorbent Fe3O4/HCO was found to be efficient for treating antimony-containing wastewater However, ineffective methodology for preparation limited its effective adsorption capacity and thus wider application. In this study, a new type of HCO-doped-(Fe3O4)x adsorbent was prepared by co-precipitation method for doping Fe3O4 into HCO sludge (HCO), thereby improving adsorption performance for Sb(III) and Sb(V) ions, with the maximum adsorbing capacity being 44.46 mg/g and 47.91 mg/g, respectively. According to the results of BET, SEM-EDS, XRD and XPS, it were confirmed that the FeOOH and X≡Fe-OH were formed during the preparation process, bring about the increased the surface area, thus resulting in further increase of surface area, hydroxyl groups and the net negative ionic charge. Moreover, the adsorption kinetics followed the pseudo-second-order kinetic model which indicated that adsorption process of Sb(III)/Sb(V) by HCO-doped-(Fe3O4)x adsorbent was controlled by chemical reaction. The main adsorption mechanism is that antimony ion and amorphous iron oxide X≡Fe-OH undergo coordination exchange reaction and complexation reaction with CeO2 or Ce2O3. Furthermore, HCO-doped-(Fe3O4)x could adapt to wide pH and had stable adsorption ability after regeneration. The good adsorption performance of HCO-doped-(Fe3O4)x makes it a potential applications of adsorbent for removal of antimony.