Russian Journal of Physical Chemistry A最新文献

Principles of approaches used to describe molecular flows in dispersed phases are discussed. The approaches are based on the current continuum mechanics methods, the physical interpretation of hydrodynamics and non-equilibrium thermodynamics that differently introduce the concept of pressure in the bulk phase. Differences are emphasized in these three mentioned model-free methods of determining the pressure, which equally imply the use of experimental data and do not allow the calculation of the pressure. To implement pressure calculations it is needed to apply the statistical physics methods closing the calculations of the mechanical and thermodynamic properties in wide temperature and density ranges, which also have different definitions of pressure. The calculation of pressure in fluids and three-aggregate systems of limited volumes is considered based on the lattice gas model. The introduction of local and average pressure values in these fluids is discussed along with the question how they depend on indirect interactions between solids through the fluid phase, apart from the direct surface potential effect of solids. Microscopic hydrodynamics enables the calculations of local non-equilibrium corrections in the flow to the equilibrium pair distribution function of molecules, which affect all characteristics of dispersed phases. These corrections are related to local hydrodynamic velocities, and they govern the conditions of local equilibrium used to calculate local dissipative coefficients in any part of the system. It is shown that in all situations, the second law of thermodynamics makes it possible to indicate the correct definitions of the pressure value, which provides the possibility of its modeling.

The thermal effects of the protolytic equilibria of ethylenediamine-N,N,N',N'-tetrapropionic acid (EDTP) at 298.15 K and ionic strengths of 0.1, 0.5, and 1.0 (KNO₃) were determined by direct calorimetry. The standard thermodynamic characteristics (pK°, Δ_disG°, Δ_disH°, Δ_disS°) of the stepwise dissociation reactions of this complexon were calculated using the combined results of thermochemical and potentiometric studies performed under identical experimental conditions. The results were compared with the corresponding data for related compounds.

The results of the study and use of chemical factors that make it possible to control flame propagation and gas explosion and detonation are presented. In view of the chain nature of reactions in these processes, an important role of heterogeneous reactions of atoms and radicals in all combustion modes was discovered. The tendencies in explosion and detonation inhibition are discussed; examples of control over the explosion intensity and detonation velocity by using inhibitors and by varying the chemical properties of the reactor surface are given.

Data on the influence of high hydrostatic pressure on the rate constants (equilibrium constants) of polar and isopolar reactions were collected and analyzed. An equation was derived for determination of the activation volume (reaction volume) from only two values of the rate constants (equilibrium constants) at atmospheric pressure and 1000 bar. The differences between experimental activation (reaction) volumes and those calculated using the equation derived are within the standard errors of experimental determination of this volume parameter.

The interaction of o-bromobenzoic acid with the surface of dispersed ice was studied by the method of sorption from solution. It is shown that at low concentrations, sorption is caused by a transition of the acid from solution into the quasi-liquid film on the ice surface. At increased concentrations, sorption abruptly increases due to the thickening of the transition film associated with the melting of the bulk phase of ice bordering the film. This is followed by a slowdown in acid sorption due to the adsorption of acid molecules on the surface of ice particles, which prevents the penetration of hydroxonium ions into the quasi-liquid film.

A crystalline sample of 5-amino-1H-tetrazole synthesized by us was used. The enthalpies of solution of crystalline 5-amino-1H-tetrazole in an aqueous KOH solution at 298.15 K were measured by a direct calorimetric method. The equilibrium composition of the system, including the stepwise dissociation of 5-amino-1H-tetrazole and water dissociation, was calculated using the KEV program. The standard enthalpies of formation of 5-amino-1H-tetrazole and its dissociation products in aqueous solution were calculated.

The experimental isotherms of carbon dioxide adsorption by the metal-organic frameworks MOF-177 and MOF-505 and by the activated carbon Norit RB2 at 25°C were interpreted within the framework of the cluster adsorption model. It is shown that CO₂ molecules are adsorbed into the first layer of the sorbent in the form of monomers and clusters of different sizes. The equilibrium coefficients of the reactions of formation of monomers and clusters on the sorbent, the monolayer capacity, and the number of molecules in the sorbate clusters, which are the parameters of the cluster model, were determined graphically and by the least squares method. To confirm the cluster nature of adsorption, the criterion of clustering of sorbate molecules introduced in previous works was used.

In this paper, BiFeO₃ and BiFe(_{{(1 - x)}})Ni_xO₃ (x = 0.01, 0.03, 0.05) nanoparticles were synthesized by the sol–gel method. As an intrinsic ferromagnetic material, these nanoparticles can be easily recovered from the solvent system. The photocatalytic activity of these nanoparticles was evaluated by degrading quinoline yellow as a pollutant under UV light. The structural properties and morphology of the synthesized nanoparticles were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (FE-SEM). The effect of various parameters on the photocatalytic degradation of quinoline yellow dye, including dye concentration, contact time, amount of H₂O₂, pH, and catalyst dose, was investigated and optimized. The photocatalytic degradation of quinoline yellow dye with a concentration of 8 mg/L, 0.1 g of catalyst dosage, and 1 mL of H₂O₂, under ultraviolet irradiation of a 250 W mercury lamp at pH 2 for 180 min, was: 60.48, 52, 58, 93% for values of x = 0.00, 0.01, 0.03, 0.05 in BiFe(_{{1-x}})Ni_xO₃ samples, respectively. Additionally, the experimental results of the photocatalytic degradation of quinoline yellow were fitted to the pseudo-first-order kinetic model.

This study advances the design of red thermally activated delayed fluorescence (TADF) emitters, crucial for the development of organic light-emitting diode (OLED) technologies. We present a straightforward and effective donor-engineering strategy by replacing the conventional triphenylamine (TPA) donor with an oxygen-bridged benzo[5,6][1,4]oxazino[2,3,4-kl]phenoxazine (BOP) donor. This substitution yields four newly designed emitters—BOPAP, BOPAQ, DCPA-BOP, and BOPAZ—that exhibit red-shifted and enhanced near-infrared (NIR) emission characteristics. Vertical excitation energies were calculated using both ground-state (S₀) and excited-state (S₁) geometries for the reported and newly designed molecules. In particular, vertical excitation energies derived from S₀ geometries were compared with experimentally observed photoluminescence (PL) λ_max values for near-infrared (NIR) TADF materials incorporating pyrazine-based acceptors. These calculations, performed using TD-DFT at both the B3LYP/6-31G* and HSE06/6-31G* levels of theory, showed good qualitative agreement with the experimental emission data. This validates the use of S₀-based vertical excitation energies as reliable predictors of emission trends in reported TADF emitters. Based on these findings, among the newly designed compounds, BOPAZ demonstrates the most promising performance, featuring a small singlet–triplet energy gap (ΔE_ST = 0.045 eV), a high predicted reverse intersystem crossing (RISC) rate of 3.47 × 10⁵ s^–1, and a vertical excitation wavelength of 814 nm—indicative of strong NIR emission potential. In contrast, the reference compound TPAAZ shows a lower RISC rate (2.46 × 10⁴ s^–1; experimental: 6.83 × 10¹ s^–1) and a predicted vertical excitation of 686 nm, compared to its experimental PL λ_max of 742 nm. These findings underscore the importance of rational donor modification in optimizing charge-transfer interactions and emission efficiency. Overall, our results provide valuable insights into the development of next-generation red and NIR TADF materials for advanced OLED applications.

This study focused on synthesizing TPT-COF as an adsorbent and assessing its effectiveness in capturing two categories of antibiotics: tetracycline and quinolone, specifically targeting doxycycline (DOX) and ciprofloxacin (CIP). X-ray diffraction analysis revealed distinct, sharp peaks in the COF, confirming its high crystallinity. FE-SEM imaging showed that TPT-COF possessed a rod-like morphology, accompanied by filamentous structures that pointed to the presence of a polymeric network. Various parameters influencing antibiotic adsorption were thoroughly investigated, including pH values (spanning from 2 to 10), adsorbent masses (10–90 mg), initial antibiotic concentrations (20–60 mg/L), and contact times (20–100 min). Optimal conditions for the adsorption of DOX and CIP were identified as a pH of 6, an equilibrium time of 60 min, and adsorbent doses of 50 mg for DOX and 70 mg for CIP. Experimental equilibrium data were analyzed using adsorption isotherms based on the Langmuir and the Freundlich models, with the associated parameters calculated. The findings indicated that the adsorption of DOX and CIP antibiotics onto TPT‑COF aligned with the Freundlich isotherm. For both DOX and CIP, the adsorption data demonstrated a stronger correlation with the pseudo-second-order kinetic model (R² = 0.9945 and 0.9929, respectively) compared to the pseudo-first-order model at pH 6. Additionally, various thermodynamic properties, including Gibbs free energy, enthalpy, and entropy, were assessed. The results confirmed that the process is endothermic and occurs spontaneously. These observations offer valuable insights into water purification technologies and open up avenues for further scientific exploration and practical industrial applications.