Vol 99, No 5 (2025)

The solubility of tetra-4- and tetra-3-substituted copper phthalocyaninates with ortho-, meta-, or para-phenol moieties in the temperature range 288–318 K is studied. Regularities of dissolution of the compounds in chloroform depending on the position of the substituent located at the periphery of the molecule are discussed. Standard thermodynamic parameters of dissolution of synthesized metal complexes are calculated.

Thermal analysis of mixtures ofvarious alumina precursors (powders of fused corundum, smelter-grade alumina GKand non-smelter-grade alumina G-00, combustion product of xerogel from aluminumnitrate and citric acid) with periclase at different heating ratesis performed. By analyzing the shape and position of exothermicpeaks, which corresponded to the formation of magnesia spinel MgAl2O4, the values of the Avrami coefficient and theeffective values of the activation energy are determined according toKissinger, Augis-Bennett, and Ozawa equations. The effect of mechanoactivation (MA)of the reactants is analyzed. Co-treatment of periclase and corundum-containingreagents allowed reducing the activation energy of the reaction by15–20%. Pre-treatment of one of the components of the mixtureis most appropriate for periclase since it allowed reducingЕаby ~14%, whereas MA of corundum alone reduced thischaracteristic only by ~9%. Using the combustion product ofxerogel of alumina-oxide composition in spinel synthesis is very effectivesince it accelerated the process by reducingЕаby~11% even without MA. The values of the Avrami constantare found to be in the range 0.57–0.76, which correspondsto the mechanism of nucleation and crystal growth.

Kinetic and diffusionparameters of sorption of Co2+ions under static conditions fromaqueous solutions of cobalt chloride without salt background by asorbent based on industrial waste (borogypsum) obtained by their autoclavetreatment are studied. Kinetic curves of sorption of Co2+ions at temperatures from 20, 40, and 60°C areobtained and analyzed by chemical kinetics models. Thermodynamic parameters suchas the standard enthalpy (ΔH°), standard entropy (ΔS°), and standard free energy (ΔG°) are calculated. The diffusion coefficients of Co2+ionsin selected temperature modes are determined.

Existence of a new type of nonvariantpoints on isotherm-isobaric solubility diagrams of multicomponent systems is described.Realization of such nonvariant points is directly related to crystallizationof solid phases based on pure solvents at temperatures belowthe crystallization temperatures of the latter in single-component systems. Atype of nonvariant processes occurring at these points during isothermalevaporation of the solvent and stability of monovariant equilibria inthe nearest neighborhood of nonvariant points are considered. Characteristic examplesof realization of such nonvariant equilibria are presented by theexample of three- and four-component (mutual) water-salt systems.

The films of polymer nanocomposites based on poly-p-xylenecontaining cadmium sulfide (CdS) as a filler were studied byX-ray diffraction and IR spectroscopy. The films were synthesized bygas-phase polymerization on the surface by joint vapor deposition ofp-xylene monomer and CdS, had thicknesses of ~0.2, ~0.5, ~1 and ~1.5μm, and contained from 5to 90 vol. % of CdS. It is shown that insuch films, depending on their thickness and filler content, CdSnanoparticles can be both X-ray amorphous and crystalline oriented withwurtzite-type structure (size ~30 nm) or with RCP structure (size~9 nm). The polymer matrix in the vast majority offilms is X-ray amorphous and yet oriented in some films.Oxygen-containing compounds are identified in many films, which appear tobe formed as a result of partial oxidation of thefilms when they are exposed to air after synthesis. Possibleinfluence of these compounds on the structure formation of CdSnanoparticles is discussed.

The sorption/desorption behavior of divalent ions (Cu2+, Mn2+,Co2+, Ni2+) on amorphous titanium phosphate is studied.The sorption/desorption equilibrium is shown to be largely determined bythe solvated state of heavy metal cations; selectivity series areconstructed. Regardless of the degree of saturation of the sorbentwith cations of the metals being studied, the desorption degreeexceeds 99.9% in all cases. With multi-stage use of thesorbent, the efficiency of sorption/desorption processes is established to decreasebecause of its dehydration due to hydrolysis of the sorbent,which is 2.6 10–3 mg g–1·h–1. The efficiencyof sorption/desorption of the ions from multicomponent solutions is shown.

Electrochemical synthesis of hydrogen peroxideon anthraquinone-modified carbon/polymer composite is performed. The method of chemicalmodification of the electrode is improved by using the water-acetonitrilemedium and acetone for sorbent purification; the electrode potential andpolarization time is found to affect the hydrogen peroxide production.During oxygen electroreduction, hydrogen peroxide was accumulated by potentiostatic cathodicpolarization of a gas diffusion electrode with a thin filmof anthraquinone-modified carbon/polymer composite coated on it. The anthraquinone introductionis found to lead to the maximum of hydrogen peroxideaccumulation appearing in the first polarization wave of the cathodicoxygen reduction, thus reducing hydrogen peroxide formation overpotential and increasingthe current yield.

The phase analysisof nanocrystalline alloys of composition (Fe_0.97-xCr_xSi_0.03)₇₅C₂₅, wherex = 0.05and 0.10, in the states after mechanosynthesis (MS) and subsequentannealing is performed by methods of X-ray diffraction, Mössbauer spectroscopy,and magnetic measurements. MS yields ~46–58 vol. % of the X-rayamorphous phase (XAP), ~30–39 vol. % ofχ-carbide, and only ~9–11vol. % of cementite. Mechanosynthesized carbides are doped both with chromiumand silicon. During annealing in the temperature rangeТ_ann=400–500°C, the process of silicon release from carbides withits subsequent dissolution in ferrite is completed. XAP crystallization istwo-stage. The first stage (Т_ann < 500°C) is characterizedby carbides formed out of Si-depleted regions of XAP. Atthe second stage (Т_ann ≥500°C), the residual XAPdecomposes to form ferrite and cementite with a higher concentrationof Cr than that of the cementite formed both atthe first stage of XAP crystallization and during MS. Furtherincrease of Тann leads to a more homogeneous distribution ofchromium atoms in cementite.

Influenceof stearic acid and graphite additives during mechanical alloying oftitanium and silicon in petroleum ether on the structural-phase stateand stability of titanium carbosilicide during annealing up to 1300°Cis studied. Barrier layers on the particles formed inthe presence of surfactants are shown to enhance stability ofcarbosilicide more effectively than graphite does. Surfactant additives promote theformation of additional silicon-containing phase and more efficient sintering ofparticles.

An analytical form of the diagram of equilibrium structural-phase states ofnanocrystalline binary substitution alloys is developed and presented by methodsof mathematical simulation. It is shown that plastic deformation ofmultiphase nanocrystalline alloys accompanied by processes of complete dissolution ofsecondary phases most probably results in equilibrium chemically inhomogeneous single-phasesolid solutions of different degrees of saturation by impurity atomsbeing formed. Chemical inhomogeneities in single-phase states of nanocrystalline alloysarise due to the fact that intercrystalline boundaries generate inhomogeneousfields of electromagnetic and deformation origin in the sample volume.

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