Том 59, № 3 (2023)

The results of a study of sorption properties of native and modified materials of polysaccharide and polyamide nature are presented, and the physicochemical regularities of the distribution of d-metals in a “biopolymer–aqueous solution” heterophase system have been established. The experimental sorption isotherms were analyzed within the framework of the Langmuir, Freundlich, and Dubinin–Radushkevich models. The sorption kinetics is most correctly described by the pseudo-second-order model. The influence of various factors affecting sorption efficiency such as temperature, mixing rate and others was examined. The effect of the environment pH on the sorption of heavy-metal ions onto polysaccharide and polyamide sorbents was observed. A number of regularities of the competitive sorption process of М2+/Н+ cations within the acid pH region with the involvement of various functional groups was established. The prospects are determined for the use of polysaccharide and polyamide biosorbents modified by employing new techniques that include a directional modification of surface properties based on the “structure–sorption activity” relationship.

The methods of scanning electron microscopy and low-temperature nitrogen adsorption were applied to assess the state of the surface and the formation of a multimodal pore system in the xylem of linen waste modified to obtain air filters. The change in the structure of the modified lignin was traced by Fourier IR spectroscopy. The sorption properties of native and biomodified shives with respect to phenol and m‑cresol vapors were studied at a temperature of 298–333 K, and the chemisorption indices for polysaccharide components and lignin were differentiated. An adequate description of the sorption kinetics is provided by a pseudo-second-order kinetic model. According to the specific volume of retained sorbate, the thermodynamic parameters of sorption of phenol and m-cresol vapors were determined. According to the results of comparison of sorption characteristics with data for absorption of ortho and para isomers of cresol, generalized patterns of sorption of volatile phenolic compounds were revealed, taking into account the structural features of flax shive lignin and the position of the substituent in the sorbate molecule.

The possibility of controlling the hydrogen content and storage in polycrystalline palladium has been elucidated by the internal-friction technique, in which the characteristics of local dissipative processes are analyzed to establish the interplay between the structural changes in a system during hydrogenation and dilution of a metal. The growth of the modulus of the @  solid solution up to the palladium modulus value has been explained by a decrease in the lattice constant due to the release of hydrogen atoms from it. The internal-friction method has also been used to analyze the dissipative processes in cadmium and copper in order to evaluate the possibility of their use for modifying the palladium surface to prevent desorption of hydrogen atoms from the 
–air interface. Spectral analysis has disclosed the possibility of violation of the adhesive contact of their surface layers and the palladium matrix upon variation in the temperature and frequency conditions, which points the way toward further use of the high-temperature polymer systems as blocking coatings.

The nature is presented of an anomaly on the temperature dependence of the resistance, heat capacity, and thermal diffusion of a polymer composite based on multiwalled carbon nanotubes and polytetrafluoroethylene in the range 298 < T < 450 K. The heat release of the nanocomposite was studied in order to establish the anisotropic nature of the distribution of heat release on the surface of the composite, which depends on the vertical or horizontal arrangement of the electrodes.

Composite electrochemical coatings (CECs) based on nickel modified with multilayer graphene oxide (GO) are obtained in the pulse electrolysis mode from a sulfate–chloride electrolyte. The microstructure of these CECs is studied by X-ray diffraction analysis and scanning electron microscopy. It is found that the microhardness of nickel–GO CECs increases approximately 1.40-fold in comparison with pure nickel. The corrosion electrochemical behavior of the nickel–GO composite coatings in 0.5 M H2SO4 is studied. It is found based on the tests in a 3% solution of NaCl that, in the case of including GO particles into the composition of electrolytic deposits of nickel, their corrosion resistance increases 1.50-fold.

The effect of the oxygen content in tantalum powders of different natures on the leakage currents of capacitor anodes has been examined. It has been established that the leakage current in the anodes from magnesium thermal powders with a highly developed surface depends on the oxygen content in them more weakly than in anodes from powders consisting of fragmented particles, which have a smaller surface area. This is explained by the fact that, during sintering of the anodes from powders with a large specific surface, the majority of the oxygen of the natural oxide interacts with the metal with the formation of Ta2O5 particles outside the tantalum particle volume.

The potentiodynamic method was used to study the influence of the cadmium complex of nitrilo-tris-methylenephosphonic acid Na4[Cd(H2O)N(CH2PO3)3]·7H2O on the corrosion-electrochemical behavior of low-carbon steel in neutral aqueous media in the presence of Cl ions-. The composition and structure of passive films formed at different potentials and composition of the medium were studied by X-ray photoelectron spectroscopy with layer-by-layer etching. When the content of Cl– ions up to 20 mg/dm3 Na4[Cd(H2O)N(CH2PO3)3]·7H2O at a concentration of 0.025–1.00 g/dm3 acts as a corrosion inhibitor, reducing the current density of anodic dissolution of the metal, and, at a concentration of more than 1.00 g/dm3, encouraging corrosion. The minimum corrosion rate is achieved at a concentration of Na4[Cd(H2O)N(CH2PO3)3]·7H2O 0.15 g/dm3 regardless of the concentration of Cl– ions. At Cl– ion concentrations of 50 mg/dm3 and more, Na4[Cd(H2O)N(CH2PO3)3]·7H2O is ineffective as a corrosion inhibitor.