Том 59, № 2 (2023)

The adsorption-structural characteristics of diatomite and the surface charge density of diatomite were studied in the solution pH range of 1–14. It was found that the sign of the diatomite surface charge changes from positive (in the pH range of 1–5.5) to negative (in the pH range of 5.5–14) at pHPZC 5.5. The adsorption of an anionic organic compound, eosin H, which is readily soluble in water, on diatomite has been studied. It was found that, with an increase in the pH of the solution and with a decrease in the surface charge density of diatomite, the adsorption of eosin H on diatomite decreases. A probable mechanism for the adsorption of anionic organic compounds on diatomite is proposed.

In this work, a study was made of the sorption of boric acid from aqueous solutions by fibers of the FIBAN brand (Institute of Physical Organic Chemistry of the National Academy of Sciences of Belarus, Belarus), which have functional amino groups in their structure. The possibility of using FIBAN A-1, A-5, and A-6 fibrous materials for the extraction of boron compounds from aqueous solutions has been established. According to the sorption kinetic curves, a high rate of sorption of boric acid by high- and low-basic anion exchangers was noted. Also, some equilibrium characteristics of analyte sorption by the studied sorbents are estimated in the work. A complex multivariant mechanism of sorption of boric acid by FIBAN A-1 and A-5 fibers was revealed, which includes both chemisorption uptake of H3BO3 by amino groups of sorbents in the range of low concentrations and the possibility of formation and fixation of polyborates in the phase of the ion exchanger in the range of high concentrations (superequivalent sorption).

The degree of extraction of silver and copper from solutions of their salts by atomic hydrogen in Pd was studied, as well as the conditions for their most complete extraction. The Ag+ concentration was 12.67 and 0.635 g/L, and that of Cu2+ was 1.145 and 1.527 g/L. The residence time of Pd in solution was 1 h. Electrochemical hydrogenation of Pd was carried out in 1 M NaOH solution at 30 mA/cm2 for 9 min until completely saturated with hydrogen, at which H : Pd was 0.73. It has been established that the PdH system has the ability to efficiently extract silver (and copper) with 100% yield if the amount of hydrogen in Pd exceeds the amount of Ag in solution. The main conditions for this are solutions diluted with silver (with respect to copper) and a large working surface of Pd samples. It has been established that the chemical deposition of silver on PdH is accompanied by the formation of colloidal silver near the surface, which can be isolated from the solution. The main condition for this is a low hydrogen content in the sample (Н : Pd < 0.3). The result of this is a decrease in the rate of hydrogen diffusion to the sample–solution interface, and the lifetime of the colloid increases.

In this work, the effects of adsorbed water on the structural evolution in the PVDF layer of composite hydrophobic MFFC-3 and hydrophilic MFFC-3G membranes were studied using ATR IR spectroscopy. It has been found that adsorbed water molecules initiate the conformational rearrangement of PVDF polymer molecules in the hydrophilic membrane layer, while the conformation of PVDF polymer molecules in the hydrophobic membrane layer does not change. The deconvolution of the absorption bands of the stretching vibrations of OH groups was carried out using four Gaussians. Based on the frequencies of the Gaussian peaks, the energy was calculated and the hydrogen bonds of adsorbed water were classified. It is shown that the structure of adsorbed water with hydrogen bond energies EOH = 42.8, 35.7, 17.9, and 14 kJ/mol are “clusters” with three or four hydrogen bonds. Energy values EOH = 17.9, 10.6, 16.8, and 14 kJ/mol correspond to OH bonds of dimeric and monomeric water molecules. It is concluded that the structure of adsorbed water in the PVDF layer can be characterized by a mixed model of hydrogen bonds, consisting of monomeric, dimeric molecules, and associated clusters with hydrogen bond energies from 10.6 to 42.8 kJ/mol. A comparative analysis of the ATR IR spectra of water-saturated samples indicates that the adsorbed water molecules in the PVDF “polymer–water” interfacial space of the hydrophobic membrane do not form a layer of bound water, while, in the hydrophilic membrane, water enters the structure of molecules, forming a layer of bound water.

A study was made of a thermal interface based on a two-dimensional allotropic modification of carbon (graphene), presented in the form of a powder, for cooling integrated circuits. Such physical properties of the thermal interface as thermal conductivity, heat capacity, thermal diffusivity, and density are determined by the empirical method. The process of heat transfer in the most efficient thermal interface sample during the operation of integrated circuits in the ANSYS engineering analysis system is presented. The prospects of using pressed graphene powder as a thermal interface in order to eliminate the use of a binder are described. The paper also makes a comparison with the most effective type of thermal interfaces currently in use.

The electrochemical and corrosion behavior of Fe80.22Si8.25Nb10.09Cu1.44 amorphous metal alloy (AMA) was studied in alkali water solutions with the addition of potassium thiocyanate. An increase in the rate of electrode processes (stimulation) in comparison with the base solution was observed at a KSCN concentration of 0.5, 1.0, and 10.0 mM. At a concentration of 5.0 mM, there was a reduction in both cathodic and anodic processes (inhibition). These findings were interpreted within the framework of an electrochemical mechanism and specific structural features of the electrode material. A change in mechanical properties of AMA after exposure of the alkaline medium with a composition of 0.5 М KON + y mM KSCN, where y = 0.5, 1.0, 5.0, and 10.0, was studied. A change in surface roughness has been established. The fracture pattern changed from a brittle cleavage without influence of the environment to the plastic destruction with crack branching and formation of folded structures for all used solutions. After exposure of the 0.5 М KON + 5 mM KSCN solution, a twofold decrease in tensile strength and Young’s modulus was observed. An increase in the KSCN concentration leads to an increase in surface microhardness.

The effect of the hardening conditions and the nature of the filler and the organic modifier on the physical and mechanical properties of coatings based on a cycloaliphatic epoxy matrix filled with muscovite mica and TiO2 has been studied. The dependence of the values of hardness and the wetting angle on the amount of polyetheramine hardener (20–50 wt %) has been presented. The effect of the nature of the hardener and additives of ground granite and SiO2 microspheres on the values of hardness, adhesion, and impact and bending strengths of the epoxy coating has been studied. Four optimal compositions of epoxy coatings for the study of thermal stability and anticorrosive properties have been determined. It has been shown that coatings containing oligoethoxysiloxanes as organic modifiers are characterized by low degree of corrosion protection.