The interactions of metal ions with fulvic acids resulted in changes in the particle size and charge. Particle size distribution was trimodal for fulvic acids, bimodal for fulvic complexes with calcium and magnesium, and copper-fulvic complexes had only one size fraction. The compensation of negative charge of carboxylic and phenolic functional groups by positive charged metal ions resulted in the increase in zeta potential which was getting closer to zero in the case of copper-fulvic complexes. However, all metal humic complexes behaved as colloidally unstable which resulted in visually observable sedimentation. Calorimetric measurements provided positive values of changes in enthalpy which indicated endothermic processes. In contrast quantum chemical calculations as well as experiments with model compounds provided negative values indicated exothermic processes. Changes in Gibbs energy were determined as negative and changes in entropy as positive which meant spontaneous processes.

The present review is dedicated to using of peat on the example of fen peat in high added-value products and applications. Mainly, but not limited, last decade literature was analysed from the perspective of innovation potential of peat applications in environmental technologies on examples of studies from the Baltic Sea region. Paper covers a wide range of applications of peat products started from agriculture to medicine and cosmetics. A separate chapter is devoted to the deep-processed peat product - humic substances (humate, humic and fulvic salts and acids). Generalised dependence of product extraction rate and its properties, depending on the process parameters are provided. Widely are described applications of the humic sub-stance applications covering economic aspects, such as production costs. In the last chapter of the review are given recommendations for applications considering the most recent trends of peat-based product developments. This accumulated information could be useful for future production, development of new, environmentally friendly products and start-ups establishment.

This work presents the results of a comprehensive physico-chemical and biological study of hu-mic substances samples – an extract of humic and fulvic acids. The performed loss on drying test showed a 22 times different dry matter content between EHS and FA. The morphology and dis-tribution of particles in the dry residue of the samples assessed using the methods of optical and digital microscopy demonstrated differences in the qualitative features of the microstructures of their surfaces and granulometries. Shimadzu X-ray fluorescence spectrometry revealed Si (8.1 and 1.7%), P (33.5 and 2.7%), S (4.3 and 59.5%), K (1.35 and 2.5%), Ca (10.9 and 3.2%), Mn (0.27 and 0.06%), Fe (11 and 0.05%), Cu (0.16 and 0.45%), Zn (0.06 and 0.02%) in the dry residues of the EHS and FA samples, respectively. A high intensity of the X-ray fluorescence signal for Fe atoms in the EHS sample was demonstrated. The FT-IR spectra for EHS and FA are characterized by simi-lar vibration frequencies that are characteristic of the chromone derivatives (1-benzopyran-4-one). The UV absorption spectrum is characterized by max = 281 nm for FA. The EHS solution showed a fluorescence maximum at em = 560 nm at ex = 280 nm. Using the DLS method, nanoparticles of 1 nm and 200 nm were detected in EHS and FA diluted solutions, which are likely to condition the biochemical and physical properties of humic acids. Using the Spiro-tox-test method, the absence of the toxic effect of humic acids on the cell model of ciliates Sp. am-bigua was established. When the cell model was incubated in a solution of a toxicant of the fluo-roquinolone group, a decrease in toxicity was demonstrated when diluted with the EHS solu-tion. The results of the study of the antiviral activity of EHS and FA showed that the study ob-jects in the culture of Vero-E6 cells, in doses non-toxic to cells, suppress the reproduction of the SARS-CoV-2 virus both in the study of the virucidal effect and in the study of the antiviral activ-ity according to the therapeutic and prophylactic model scheme of injection. The results obtained suggest that standardized drugs based on humic acids may open up new perspectives in their biomedical application as antiviral drugs.