ARTICLE | doi:10.20944/preprints202308.0681.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: recycle; circular economy; cryogenic removal
Online: 8 August 2023 (13:02:27 CEST)
Finished tanned leather are usually covered by a thin polymeric layer. This layer has the scope to change the morphological aspect of the last leather layer, as well as to improve the impermeabilization properties. Often, the finished product is refused by the final client and tanneries must restore significant quantity of materials. Therefore, it is very important to remove this finished polymeric layer, to recover the underneath tanned leather and to predispose it to a new finishing. The bonding between the polymeric film and leather is so strong that, today, only a blade shaving process can perform this separation at the expenses of also removing a layer of tanned leather and consequently reduce the leather thickness. Here, a novel separation method was developed, based on the significant difference in the dilation properties between the tanned hide and the polymeric film at low temperature. The use of cryogenic fluids, in particular the direct application of liquid nitrogen, can freeze the polymeric layer under the glass transition temperature and then inducing a brittle behaviour. The result is an easy separation without any alteration of the tanned leather layer. Thus, the process here developed, allows the reuse of the tanned leather towards a new life in the respect of the circular economy principles.
COMMUNICATION | doi:10.20944/preprints202102.0556.v1
Subject: Environmental And Earth Sciences, Waste Management And Disposal Keywords: Waste; environment; reuse; recycle; product
Online: 24 February 2021 (16:41:43 CET)
Solid waste management is a global issue that affects every individual living in the world directly or indirectly. Failing to manage the waste properly will cause harm on public health, our natural environment, and even our happiness and prosperity. When asked about the reason behind the failure of third time plastic ban in Bhutan, one of the Bhutanese said it’s because of the lack of cooperation from public to support the move of government. Clean Bhutan, a non-governmental organization (NGO) that aims Zero Waste Bhutan by 2030, has collected around 5,900 metric tons of waste from December 2014 to February 2018. This project will create some awareness regarding the management of waste at individual level when people come in contact with the family of the researcher. It also talks abot how waste management and biodiversity conservation can go side by side.
REVIEW | doi:10.20944/preprints202012.0790.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: Spent Pot Lining; SPL; Aluminum; Recycle; Toxicity
Online: 31 December 2020 (11:38:02 CET)
In this study, a summary of the processes performed on the SPL for recycling, reduction in toxicity and treatment were examined on an industrial and laboratory scale. In writing this research, an attempt has been made to address the useful processes that have taken place in this field. Spent pot lining or SPL is a type of solid waste that is produced in the aluminum production process. After 3 to 8 years, the cathode blocks become problematic and can no longer be used, and need to be replaced due to adverse effects on cell function. SPL is known to be a hazardous waste to nature due to its fluoride and cyanide content. Research has shown that SPL ingredients have destructive and very dangerous effects on human DNA, which is why they are so important to maintain and recycle.
ARTICLE | doi:10.20944/preprints202310.0936.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: waste PET; recycle; water/oil separation; high value reuse
Online: 16 October 2023 (10:59:18 CEST)
As one of the important wastes, waste PET pollutes human living and natural environment seriously. PET is an important solid waste that needs to be recycled at present. The complete degradation of PET was realized at low temperature. The lipophilic hydrophobic membrane was formed on the surface of stainless steel mesh (SSM) by a simple dip coating method, and the oil-water separation material was successfully prepared. Due to the load of degradation products, the surface roughness of SSM increased from 19.09 μm increased to 62.33 μm. The surface changed from hydrophilic to hydrophobic, and the water contact angle increased to 123o. The oil-water separation flux of modified SSM is 9825 L/(m2·h) and the separation efficiency is 98.99%. The modified SSM has good reuse performance. This hydrophobic modification method can also be used to modify other porous substrates, such as activated carbon, filter paper, foam, and other materials. In this study, the porous substrate modified by the degradation product of waste PET was used to prepare oil-water separation materials, which not only solved the problem of white pollution, but also reduced the dependence on non renewable resources in the conventional preparation methods of oil-water separation materials. The research provided new raw materials and methods for the industrial production of oil-water separation materials, and had important application prospects.
ARTICLE | doi:10.20944/preprints202210.0372.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: Keywords carbochlorination; spent lithium-ion batteries; circular economy; recycle; LiCl.
Online: 25 October 2022 (02:05:51 CEST)
The abundant use of lithium-ion batteries (LIBs) in a wide variety of electric devices and vehicles will generate a large number of depleted batteries, which contain several valuable metals such as Li, Co, Mn, and Ni present in the structure of the cathode material (LiMO2). The present work investigates chemical, technological, and environmental aspects in the treatment of such wastes, development of a methodology for the extraction of lithium, cobalt, nickel, manganese, and graphite by a carbochlorination pyrometallurgical process. Mixtures of cathode and anode materials (called black mass, mixed oxides of Li, Co, Ni, Mn, and graphite) from different LIBs, carbon black (as reducing agent), and CaCl2 (as chlorinating agent) were used. Non-isothermal thermogravimetric tests up to 850°C and isothermal tests at 700°C of the mixtures in an inert atmosphere were carried out. It was experimentally observed that the LiMO2-C-CaCl2 reaction takes place at 700°C. LiCl, Ni, and Co were obtained as final products, and to a lesser extent, CoO, NiO, and MnO2. CaCO3 was also obtained as a by-product. The obtained results show that carbochlorination is an efficient and effective alternative route for the extraction and recovery of metals from different LIBs, focused on the sustainability and circular economy
ARTICLE | doi:10.20944/preprints201810.0427.v1
Subject: Social Sciences, Political Science Keywords: Water recycle; upscaling; water governance; water availability; climate change adaptation
Online: 18 October 2018 (16:34:29 CEST)
Cleaning wastewater and using it again for secondary purposes is a measure to address water scarcity in urban areas. However, upscaling of recycled water schemes is challenging due to the possible emergence of various barriers. Based on a review of the governance literature we suggest that a set of five governance conditions is necessary for a successful upscaling of recycled water schemes; (1) policy leadership, (2) policy coordination, (3) availability of financial resources, (4) awareness of a problem, and (5) the presence of a public forum. In order to elaborate on the practical relevance of these conditions we studied a recycled water scheme currently being upscaled in Sabadell, Spain. We reviewed policy documents, conducted a set of 21 semi-structured interviews, and attended two policy meetings about the subject. Our results suggest that Sabadell meets the required conditions for upscaling reused water to a certain extent. However, the presence of a public forum is lacking. We discuss the implications of the absence of the venue and procedures for public participation in Sabadell and how it could be strengthened. Following this discussion, we conclude with some lessons for other cities that plan to upscale their recycled water schemes.
ARTICLE | doi:10.20944/preprints202306.1066.v1
Subject: Engineering, Civil Engineering Keywords: Concrete; recycle aggregate; microstructure; Nano-silica; slag; compressive strength; tensile strength; flexure strength.
Online: 15 June 2023 (02:53:21 CEST)
In this work the effect of recycled concrete aggregate modified with mineral admixtures and Nano-silica on the mechanical properties and performance of the concrete was investigated after curing in tap water for 28 and 90 days. The compressive, ƒc, indirect tensile, ƒt, and flexural, ƒb, strengths for cured concrete specimens were measured and concrete strength ratios were analyzed. The water and rapid chloride permeability were measured. SEM analysis of microstructure was, also, investigated. The coarse aggregates used were dolomite (control) and recycled concrete aggregate with the incorporation of different mineral admixtures including ground granulated blast slag and granite as well as Nano-silica. It was found that, the slump values of the dolomite concrete decreases compared with recycle aggregate concrete. The results indicate that, the concrete mix containing recycle aggregate have the highest compressive strength, tensile strength and flexural strength compered to concrete mix containing dolomite aggregate. As far as the compressive strength is concerned, the addition 1 % NS and 15 % of slag improved the physico-mechanical properties of the recycled aggregate concretes compared to the other mixes after curing in tap water.
ARTICLE | doi:10.20944/preprints202304.1217.v1
Subject: Engineering, Architecture, Building And Construction Keywords: sustainability; recycle; cement-based composites; energy performance; concrete; perlite; thermal performances; mechanical properties
Online: 29 April 2023 (05:46:08 CEST)
There is an international concern for reducing energy consumption and protecting environment by application of circular economy principles in the construction industry. The thermal resistance of concrete plays a significant role in the energy efficiency of a building, and this can be improved by using concrete products with high thermal resistance. This study analyzes the influence of perlite, as an addition, on the physico-mechanical properties of concrete, with the aim of identifying perlite concrete products that will respond to the improvement of the heat transfer resistance of the building envelope. The study examines the effect of replacing different amounts of concrete aggregates with perlite in percentages of 10%, 20%, 30% and 100%. The results show that the replacement of sand with perlite improves the thermal performance of concrete, but its mechanical properties are negatively affected. The research carried out highlighted that perlite can be successfully introduced in the production of concrete blocks used for external non-bearing walls pannels, the outstanding feature being the reduction of energy consumption in buildings. Overall, the paper identifies an efficient and environmentally friendly way of using perlite in the construction industry, improving the energy performance of buildings, and reducing the environmental impact of construction wastes.
ARTICLE | doi:10.20944/preprints201905.0155.v1
Subject: Engineering, Chemical Engineering 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/preprints201707.0069.v1
Subject: Environmental And Earth Sciences, Pollution Keywords: waste management; waste minimization; recycling; rural district municipalities; community residents; households; satisfaction levels; willingness to recycle; waste separation; municipal solid waste; benefits and barriers
Online: 25 July 2017 (05:14:07 CEST)
Whereas waste management research has focused on mostly urban municipalities in South Africa, not much is known about the current performance of waste management services from the perspective of community residents in rural municipalities. This study reports on the status and effectiveness of waste management practices from the perspective of community residents in the Umkhanyakude and Zululand Districts in the rural areas of the KwaZulu-Natal province of South Africa. Making use of structured questionnaires, primary data was obtained by interviewing 333 respondents representing households in the study area. Results have revealed several shortfalls in the provision of municipal waste management services, except for solid waste removal from households (66%), and management of landfill sites (41%). The degree of dissatisfaction for waste management services rendered was very high (97.3%). Furthermore, the majority (61.4%) of respondents were not willing to participate in waste segregation due to lack of appropriate knowledge and infrastructure. The study also pinpointed some benefits associated with waste minimization, as well as barriers constraining effective waste recycling. Based on these findings, there is a dire need for transforming current waste management practices toward increased recycling rates by creating more environmental awareness and a supporting infrastructure.