Russian Journal of Physical Chemistry A最新文献

Abstract—The crystallization of aluminophosphate gels prepared using aluminum isopropoxide with di‑n-propylamine/Al₂O₃ was equal to 1.0, 1.4, and 1.8. It has been shown that changing the template/Al₂O₃ ratio in reaction gels leads to the formation of various intermediate phases during crystallization into the AlPO₄-11 molecular sieve. A method for controlling its secondary porous structure based on regulating the template/Al₂O₃ ratio is proposed in reaction gels.

Abstract—An experimental study has been carried out on the mineralization of oxalic acid H₂C₂O₄ and other oxidation-resistant organic compounds in aqueous solutions under the influence of oxygen, ozone, and ultraviolet radiation. It was found that in acidic solutions H₂C₂O₄ does not oxidize under the influence of ozone or UV irradiation in the presence of oxygen; when exposed simultaneously to O₃ + UV it has a low rate of oxidation. The possibility of photocatalysis of the mineralization process by Mn²⁺, MnO(_{4}^{ - }), Fe³⁺, Co²⁺, BrO(_{3}^{ - }), or IO(_{3}^{ - }) ions was studied The most effective photocatalysts are Fe³⁺ ions: in their presence and under UV irradiation, a fairly rapid oxidation of oxalic acid to CO₂ occurs, as under the influence of O₃ and O₂. The conditions for maximum ozone conversion during photomineralization of oxalic acid have been found. The possibility of oxidative destruction of a more oxidation-resistant substrate, acetic acid, is shown during ozonation and UV irradiation of solutions with Fe(III) and H₂C₂O₄ additives.

A mass spectrometric study is performed of the ionization of short peptides triglycine, alanyl glutamine and prolyl leucine via electrospray ionization (ESI) and surface-activated laser desorption/ionization (SALDI) using copper sulfate crystal hydrate. It is shown that having copper ions in a solution during ERI ionization initiates the aggregation of peptide molecules with the formation of large associates of up to 7–8 peptide molecules. The effect the nature of peptides has on that of ionization is studied. During SALDI ionization, there is competitive cationization of peptide molecules by copper ions, accompanied by the formation of ions M + Cu⁺. The fragmentation of peptides and the copper cationization of decarboxylation products are also characteristic.

A study is performed of tetra-4-carboxyphthalocyanine hydroxyaluminum. The thermal effects of the dissolution of crystalline phthalocyanine in aqueous solutions with different concentrations of KOH are determined via direct calorimetry at a temperature of 298.15 K. The thermal effects of stepwise dissociation AlOHРс(4-COOH)₄ are calculated using the HEAT computer program. The enthalpies of combustion of the studied compound are determined with an IKA C6000 isoperibol calorimeter (bomb calorimetry) and used to calculate the standard enthalpies of formation of AlOHРс(4-COOH)₄ along with products of its dissociation in aqueous solutions.

The MagAîxTic program package, which is based on the theory of effective Hamiltonian for crystal field and is used to estimate the parameters of effective exchange between magnetic moments in the d‑shells, is augmented by the smaller ferromagnetic contributions to those parameters. The updated package is tested based on the example of the three-nuclear basic acetates of iron(III) and chromium(III) of the composition (mu )³-OM₃(RCOO)₆, as well as of their mixed analogs. It is shown that the developed/upgraded package is able to reproduce either orders of magnitude of the exchange parameters in the range of dozens cm^–1 or their trends upon transition from one metal to another.

Thermogravimetry (TG), differential scanning calorimetry (DSC), and the X-ray diffraction of synchrotron radiation are used to study the reactivity and formation of phases during the oxidation of aluminum-based powders in the course of programmed heating. It is shown that the combination of thermal and phase analysis using synchrotron radiation gives an idea of the mechanism of rapid oxidation in order to accelerate the selecting of modifiers to optimize the properties of dispersed systems based on aluminum, and the technological parameters of synthesizing materials with controlled properties.

Abstract—The vapor–liquid equilibrium of methanol–chloroform–tetrahydrofuran mixtures of various compositions and methanol–chloroform–tetrahydrofuran–dimethyl sulfoxide mixtures with different dimethyl sulfoxide contents at 101.32 kPa were studied experimentally. A comparison of experimental and calculated values of the relative volatility of substances in four-component mixtures was carried out. The results of extractive distillation of ternary mixtures are predicted based on experimental data and calculated data obtained using the NRTL model.

Finely dispersed shungite is studied as an effective filler for composite materials. Experimental data are obtained on the effect the concentration of the filler of a composite material has on its characteristics of absorbing and shielding from electromagnetic radiation in the radio and microwave ranges. The data can be used to produce effective radio-absorbing materials and electromagnetic screens for protecting information and against unwanted effects of electromagnetic radiation in radio engineering and the military.

Kinetic characteristics are determined for the release of chlorine during the oxidation of chloride ion in solutions Na⁺–H⁺–HSO(_{4}^{ - })–Cl⁻, Mg²⁺–H⁺–HSO(_{4}^{ - })–Cl⁻, Zn²⁺–H⁺–HSO(_{4}^{ - })–Cl⁻, Cu²⁺–H⁺–HSO(_{4}^{ - })–Cl⁻, Fe³⁺–H⁺–HSO(_{4}^{ - })–Cl⁻, Mg²⁺–H⁺–Cl⁻, and Ca²⁺–H⁺–Cl⁻. With similar experimental parameters, the rate of the reaction acquires considerably different values, depending on the nature of the added salt. This is due to the possible catalysis of the reaction between O₃ and the Cl⁻(aq) cations of some metals; the formation of chloride and sulfate metal complexes, which alters the actual concentrations of reagents; and a change in the solubility of ozone. The solubility of ozone, the values of the Henry constant, and the Sechenov coefficient are found for aqueous solutions of zinc sulfate and magnesium sulfate with concentrations of 0–1 M at temperatures of 20 and 25°C.