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Over the last 20 years, metallic silver in the form of Ag nanoparticles has made a remarkable comeback as an example of a nanomaterial for control of microorganisms. The purpose of our study was a) to quantitatively estimate the antimicrobial effect of silver nanoparticles compared with that of silver ions and b) to check the efficacy of nanosilver as an antimicrobial agent against a range of microbes on the surface of water-soluble paint, 100% cotton fabric, and fibrous chemisorbent. Minimum inhibitory concentration tests quantitatively showed that Ag nanoparticles were less efficient than Ag+ ions against representatives of gram-positive / gram-negative bacteria and cosmopolitan saprotrophic fungi. Antifungal/antibacterial effects against Aspergillus niger, Penicillium phoeniceum, and Staphylococcus aureus were confirmed for nanosilver concentrations of even 1 μg/cm2 on the surface of cotton fabric and 0.8 μg/cm2 in water-soluble paint. As the concentration of nanosilver in water-soluble paint/cotton fabric was increased to 7 μg/cm2, the growth of Bacillus subtilis and Escherichia coli was suppressed as well. Microbiological tests conducted over a period of 60 days showed that there was no biofilm growth on the surface of a silver nanoparticle-coated fiber sorbent during its everyday operation as a household water treatment filter. Thus, silver nanoparticles as an add-on to water-soluble paints, textile fabrics or fiber chemisorbents had a remarkable antibacterial/antifungal effect, although some of the Ag nanoparticles were agglomerated into larger colloidal clusters

The minimum inhibitory concentrations (MICs) assays conducted for Escherichia coli, S Staphylococcus aureus, Bacillus subtilis, and Penicillium phoeniceum cultures have shown that the antimicrobial activity of silver ions was superior to that of silver nanoparticles. The efficacy of nanosilver as an antimicrobial agent has been estimated against a range of microbes on the surface of fibrous ion-exchange sorbents. The cytotoxicity of silver nanoparticles has been studied using NIH-3T3, HEP-G2, A-549, PC-12, and Colo-320 cells via the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium-bromide) test. The obtained MTT test results have shown that silver nanoparticles with concentrations of ~1–10 ppm entering the body from air or liquid suspensions can present a potential risk to human health.

This chapter deals with a novel nanocomposite specifically developed for chemical treatment of walls, floors, ceilings, roofs, etc. to prevent or limit exposure to dangerous gases seeping into buildings through constructive materials. The developed silica-based organic nanocomposite contains the mixture of polyethylhydrosiloxane and the solution of alkyltriethoxysilane in isopropanol with a tin-based catalyst. The nanocomposite fills micropores inside the concrete or another constructive material against hazardous gases, including volatile organic compounds, organic and inorganic gases, and radioactive gases emitting alpha particles. The method allows for reducing the coefficient of gas (air, Ar, 222Rn, CO, 85Kr, 133,135Xe, etc.) permeability 200–400 times. The consumption of chemicals depends on the porosity of the materials; it is equal to 0.2 L/m2 for gypsum and 0.3–0.4 L/m2 for concrete and cement, respectively.

Over the last decade direct (forward) osmosis has attracted much attention in practical applications including artesian water desalination, green power generation, industrial water purification etc. In comparison with the traditional reverse osmosis process the separation is due to natural osmosis, providing lower energy cost for external pressure that is needed for reverse osmosis and lower membrane fouling potential. The main problem for the direct osmosis application efficiency is a selection of appropriate draw solute (otherwise known as a working substance). In the present paper diethyl ether (C2H5)2O has been considered as a working substance having a relatively high osmotic pressure. Heating regeneration has been explored to obtain fresh water and recover the proposed draw solution. The advantage of the diethyl ether over known draw solutes has been discussed. It was noted that for further commercial applications of the diethyl ether as a working substance the membrane should have better characteristics of water permeability, stability, selectivity, and mechanical strength. The pilot device based on the described direct (forward) osmosis technique with the productivity of 1 m3/hr has been manufactured. In the beginning of 2020 the pilot device was successfully installed in a village of Navoiy Region, Uzbekistan to provide its inhabitants with the clean water.

Over the last decades, extensive studies have been carried out on nano-photocatalytic materials finding a broad range of applications mainly in solar energy conversion and environmental remediation. This article focuses on synthesizing a novel nano-photocatalyst material for purifying water from chloro-organic pollutants and microbes. It was synthesized in the electrolytic cell with titanium and graphite electrodes. TEM analysis revealed that the obtained nanocarbon-titanium composite has a spherical morphology, the average dimension of nanoparticles is 6±2 nm. The electrochemically synthesized nano-photocatalyst forms OH radicals in the presence of water vapor during daylight hours under sunlight’s ultraviolet radiation. As soon as extremely reactive OH radicals are formed, they react with organic pollutants. The results of photodegradation of E. Coli, methyl orange, methyl blue, and polychlorinated biphenyls in the ultraviolet spectrum of sunlight have been discussed. The effect of pH value on the decolorization efficiency has been also observed. The obtained photodegradation time of methyl orange (MeO) and methyl blue (MeB) solutions was less than 60 minutes, and the destruction time of polychlorinated biphenyl (PCB) compounds was about 6-8 hours. The practical application of the developed nano-photocatalyst material promises to be an inexpensive, viable alternative or complimentary method for water and wastewater treatment at ambient temperature to degrade various chemical and microbiological pollutants in water.