Doklady Physical Chemistry最新文献

In this work, the isothermal solution equilibrium method was used to examine the phase equilibrium of a ternary LiCl–LiBr–CH₃OH system at 273 and 323 K. The solubilities of LiCl and LiBr in CH₃OH at different temperatures were measured by chemical analysis. The chemical composition of the equilibrium solid phase was determined via the wet slag method combined with X-ray diffraction. Thus, the corresponding phase diagram was created, and the LiCl–LiBr–CH₃OH and LiCl–LiBr–H₂O ternary systems were compared at different temperatures. The results showed that the phase diagram characteristics of the LiCl–LiBr–CH₃OH ternary system at 273 and 323 K were similar, with a saturation point, two univariable solubility curves and two solid phase crystallization zones; these zones represented the Li(Cl,Br) solid solution crystallization zone and LiCl single salt crystallization zone. The single salt of LiCl can be separated using crystallization filtration. LiBr has a salt-out effect on LiCl, but LiBr cannot be obtained. With increasing temperature, the contents of LiCl and LiBr at the saturation point of the LiCl–LiBr–CH₃OH ternary system increase, and the solubilities of LiCl and LiBr in methanol gradually increase.

In this work, TiO₂–ZrO₂ doped catalysts with different molar ratios of CuO were synthesized through a facile and mild sol-gel dip coating process. The dip-coated thin films have been examined at different annealing temperatures 500, 800, and 1000°C. Structural, optical features and photocatalytic responses of the prepared films were analyzed by X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectra, UV-VIS, photoluminescence spectroscopy (PL) techniques, X-ray diffraction (XRD), and Raman results indicated that an increase in annealing temperature from 500 to 1000°C caused a transformation of crystallinity from anatase and brookite at 500°C to rutile and monoclinic CuO phases at 1000°C, accompanied by an increase in particle sizes. The optical transmittance of the films, increased to over 90% in the visible region, indicate that copper loading decreases the band gap from 3.41 to 3.28 eV. The photoluminescence experiments revealed that doping with CuO hinders the electron-hole recombination rate, which is favorable for photocatalytic performance. Photocatalytic experiments confirmed that our films exhibited high efficiency in the degradation of methyl orange (MO) dye under UV light irradiation. The removal rate of methyl orange reached more than 99% after 3 h. Photocatalytic experiments confirmed that our catalysts displayed highly efficient and durable activity for the photodegradation of methyl orange under UV light irradiation.

To enhance the compatibility of high-volume desulfurized rubber-modified asphalt, a modified asphalt was prepared through high-temperature shearing of desulfurized rubber extruded from a twin-screw extruder with matrix asphalt and linoleic acid. The impact of linoleic acid on the performance of desulfurization asphalt rubber was examined through basic physical properties tests and rheological tests, while the influence of linoleic acid on the compatibility of desulfurization asphalt rubber and its compatibility mechanism was investigated via storage stability and infrared tests. Changes in solubility parameters and binding energy were explored using molecular dynamics simulation. The results revealed that the optimal content of linoleic acid is 6%. This method improved the compatibility of modified asphalt, resulting in a significant increase in deformation resistance and low-temperature performance, a smaller difference in solubility parameter values, and an increase in maximum binding energy for the modified asphalt. Analysis indicated that linoleic acid supplemented the light components of asphalt, enabling full swelling of desulfurized rubber particles and reducing phase separation within the modified asphalt. Furthermore, linoleic acid provided active functional groups that underwent addition and esterification reactions with desulfurized rubber and asphalt, thereby promoting compatibility within desulfurized rubber-modified asphalt.

This study investigates the structural, optical, and thermal properties of chitosan (CS) biopolymer using experimental and computational approaches. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of two key functional groups–hydroxyl (OH) and amine (NH/NH₂)–which play a crucial role in CS interactions. X-ray Diffraction (XRD) analysis revealed a mixed-phase structure, comprising both crystalline and amorphous regions. Various crystallographic parameters, including full width at half maximum (FWHM), degree of crystallinity, lattice strain, dislocation density, inter-band crystallinity, and stacking faults, indicated an increase in crystallinity with greater CS film thickness. Optical characterization using Tauc plots showed a decrease in bandgap energy from 5.54 to 5.12 eV with increasing film thickness. Urbach energy analysis allowed for the estimation of steepness parameters and electron-phonon interaction energy (E_e–ph), which exhibited a reduction from 11.398 to 10.315 eV. Computational studies were performed using Density Functional Theory (DFT) at the B3LYP/6-311++G(d,p) level via the Gaussian 09 program to determine electronic and thermal properties. Additionally, thermal properties such as entropy, heat capacity, and enthalpy were evaluated using the Materials Studio software. Monte Carlo simulations were employed to estimate the adsorption energy of CS on Fe, Al, and Cu surfaces, revealing that Fe exhibited the most stable and strong coordination with CS due to its unique coordination geometry. These findings provide valuable insights into the structural and functional characteristics of CS films, contributing to their potential applications in various fields.

The crystal structures of three organic salts of triiodaminobenzoic acid (1–3) and triiodaminobenzoic acid monohydrate (4) are described, the structural features are established by the X-ray diffraction method. Compound 1: C₂₀H₁₉I₆N₃O₆, FW 1158.78; monoclinic crystal system, space group Сс; unit cell parameters: a = 32.0782(10) Å, b = 9.5284(3) Å, c = 9.3745(3) Å; α = 90°, β = 90.0(1)°, γ = 90°; V = 2865.35(16) ų, Z = 4, ρ_X = 2.684 g/cm³. Compound 2: C₁₆H₁₅I6N₃O₄, FW 1074.71; monoclinic system, space group P2₁/c; unit cell parameters: a = 8.990(5) Å, b = 28.541(11) Å, c = 9.945(5) Å; α = γ = 90°, β = 91.23(2)°; V = 2551(2) ų, Z = 4, ρ_X = 2.798 g/cm³. Compound 3: C₁₇H₁₇I₃N₂O₄, FW 694.03; monoclinic system, space group I2/a; cell parameters: a = 36.02(2) Å, b = 7.254(5) Å, c = 16.468(9) Å; α = γ = 90°, β = 105.29(2)°; V = 4150(4) ų, Z = 8, ρ_X = 2.222 g/cm³. Compound 4: C₇H₆I₃NO₃, FW 532.83; orthorhombic system, space group Iba2; unit cell parameters: a = 30.2146(4) Å, b = 13.9830(2) Å, c = 5.80740(10) Å; α = β = γ = 90°; V = 2453.57(6) ų, Z = 8, ρ_X = 2.885 g/cm³. The 7-methylquinoline salt is devoid of halogen bonds because of the peculiarities of the stacking of flat molecules. For two compounds (3 and 4), the features of their thermolysis are determined by thermal analysis (in an argon atmosphere): at the first stage (52 and 73°C, respectively), the loss of crystallization water occurs; at 700°C thermolysis of both compounds gives glassy carbon as the decomposition product.

Strontium molybdate was prepared by fluxed-melt chemical synthesis from ionic melts of the Me,Sr||Cl,МоO₄ (Ме = Li, Na, or K) three-component reciprocal salt pair systems fluxed with the low-melting-point eutectic melt of the LiCl–NaCl–SrCl₂ three-component system as the flux electrolyte. The eutectic chloride melts used as the fluxes provided a significant decrease in temperature and an increase in reaction rate of chemical strontium molybdate synthesis in ionic melts.

High-performance polymers characterized by their exceptional thermal stability are crucial across various industries. Here, phthalonitrile resins have attracted significant attention due to their ability to form highly cross-linked networks upon curing, leading to outstanding properties suitable for demanding applications in aerospace, electronics, and automotive sectors. This study investigated the thermal curing kinetics and resulting thermal stability of phthalonitrile resins cured with 4,4'-diaminodiphenyl sulfone (DDS) and bisphenol A diglycidyl ether (DGEBA). Kissinger and Friedman methods were employed to analyze the curing process using thermogravimetric analysis data at various heating rates. The results revealed that DGEBA-cured networks exhibited higher thermal stability and activation energy compared to DDS-cured networks. This was attributed to the stronger C–O bonds formed in DGEBA networks. The higher bond dissociation energy of C–O bonds, arising from factors including electronegativity difference, bond length, orbital overlap, and hybridization necessitates a greater energy input for bond cleavage during thermal degradation. These findings highlight the critical role of curing agent selection in tailoring the thermal properties of phthalonitrile-based materials for high-performance applications.

Homogeneous and heterogeneous homophase reactions in an oscillating mode are studied. Conditions for free concentration oscillations to arise in a closed homogeneous reaction system are determined. A quantitative description is given to the oscillating mode of a heterogeneous homophase reaction with special attention paid to the formation of Liesegang patterns.

Precise estimation of aggregate size of asphaltene particles in oil reservoirs characterized with the resulted formation damage and well blockage issues are critical to the smooth oil production and successful planning of pertinent remedial tasks. In this research, it is aimed to construct data-driven soft-computing based models of Extra Trees (ET), Multilayer Perceptron Artificial Neural Network (MLP-ANN), Support Vector Machine (SVM), Convolutional Neural Network (CNN), Random Forest (RF), K-nearest Neighbors (KNN), Adaptive Boosting (AdaBoost), Ensemble Learning (EL), Decision Tree (DT), Linear Regression, Ridge Regression, and Lasso Regression to predict asphaltene aggregation size in terms of time, asphaltene concentration of model oil, heteroatoms content of asphaltenes, hydrogen content of asphaltenes, and voltage based upon previously published experimental data. A widely recognized outlier identification methodology is implemented to the collected dataset to evaluate its reliability prior to model development. Furthermore, the relevancy index is calculated for every input variable to determine its relative impact on aggregation size. K-fold cross validation algorithm is used during model training to reduce overfitting. It is indicated that in contrast to asphaltene hydrogen content, other parameters such as voltage, time, asphaltene concentration and hydrogen content of asphaltenes are all directly influencing aggregate size. Moreover, both graphical and statistical evaluations demonstrate that the CNN model surpasses all other examined constructed models in performance as evidenced with lowest value in mean squared error and largest value of coefficient of determination.

Nitrogen-doping of platinum/carbon (Pt/C) catalysts in proton exchange membrane fuel cells (PEMFCs) have garnered significant attention due to its potential to enhance catalyst performance by improving the dispersion and stability of Pt nanoparticles. However, the leaching of nitrogen dopants (N-dopants) under the harsh operational conditions of PEMFCs presents a formidable challenge, leading to catalyst degradation and reduced fuel cell efficiency. Understanding this issue is critical for advancing the development of durable and cost-effective PEMFC catalysts. This review critically examines the mechanisms of N-dopant leaching, encompassing electrochemical factors. By integrating insights from recent experimental and theoretical studies, this review recognizes the primary causes of N-dopant leaching and evaluates various mitigation strategies. Key findings include the identification of specific degradation pathways and the effectiveness of different stabilization techniques. The implications of these findings suggest new directions for catalyst design, aiming to improve the stability and longevity of N-doped Pt/C catalysts for PEMFC. This review concludes with recommendations for future research, emphasizing the need for continued exploration of innovative approaches to enhance the durability of N-doped Pt/C catalysts.