Russian Journal of Physical Chemistry A最新文献

Producing high-density fuel of alkylated decalins from hydrodeoxygenation (HDO) of naphthalene derivatives is an environmentally friendly but still challenging method. Herein, a bifunctional Ru/HZSM-5 catalyst was fabricated by acid treatment (citric acid, oxalic acid, nitric acid) to effectively synthesize the alkylated decalins via HDO of naphthalene derivative. Acid treatment adjusted the acidic site distribution of Ru/HZSM-5. Nitric acid treatment (NA) resulted in more abundance of weak acidic sites which was beneficial for the dehydration process in HDO, and the lowest ratio of BAS/LAS to promote the hydrogenation of alkylated octalins, the rate-determining step of HDO. NA-treated Ru/HZSM-5 showed the highest HDO activity with the highest selectivity of 1,2-dimethyldecalin (74%). Besides, it also presents good HDO activity of naphthalene derivatives to produce high-density hydrocarbons. Therefore, Ru/HZ5-NA is a promising catalyst for the production of alkylated decalins and other high-value biofuels and chemicals.

The kinetic tendencies in the destruction of cephalosporin antibiotics (ceftriaxone (CEF)) in photoinitiated oxidative systems were studied using a xenon lamp as a source of quasisolar radiation (UV–Vis). It was established that the oxidative systems under study can be arranged in the following series according to the efficiency and rate of antibiotic destruction: {UV–Vis/Fe²⁺/S₂O(_{8}^{{2 - }})} > {Fe²⁺/S₂O(_{8}^{{2 - }})} ( gg ) {UV–Vis/S₂O(_{8}^{{2 - }})} > {UV–Vis}. The optimum conditions for the oxidative destruction of CEF in the {UV–Vis/Fe²⁺/S₂O(_{8}^{{2 - }})} system are reached at [S₂O(_{8}^{{2 - }})] : [CEF] = 30 : 1 and [S₂O(_{8}^{{2 - }})] : [Fe²⁺] = 1 : 0.1. As the temperature increases to 40°C, the initial CEF oxidation rate and efficiency increase. The apparent activation energy of the CEF oxidation in the {UV–Vis/Fe²⁺/S₂O(_{8}^{{2 - }})} system was 45 kJ mol^–1, which is comparable to the values obtained for cephalosporin antibiotics. It was proved, using inhibitors of radical reactions, that the oxidative destruction of CEF in combined {UV–Vis/Fe²⁺/S₂O(_{8}^{{2 - }})} proceeds by a multiradical mechanism involving reactive oxygen species (ROS): hydroxyl radicals and sulfate and superoxide radical anions. The obtained tendencies are in good agreement with the results of open-air studies with natural solar radiation; in the {Solar/Fe²⁺/S₂O(_{8}^{{2 - }})} system, the oxidation of CEF is significantly intensified due to combined activation of persulfate by the iron ions, the UV-C (<300 nm) component of natural solar radiation, and the thermal exposure. The results indicate that using the combined {Solar/Fe²⁺/S₂O(_{8}^{{2 - }})} oxidation system is promising for the destruction of antibiotics in order to reduce their release into the environment.

Densimetry is used to study the interaction between L-histidine (His) and nicotinic (NA), isonicotinic (INA), and picolinic acids (PA) in an aqueous buffer solution in the 288.15–313.15 K range of temperatures. Data on density are used to determine the apparent molar volumes and limiting apparent molar volumes of pyridine monocarboxylic acid (PyCOOH) isomers at infinite dilution, along with their temperature derivatives in a buffer solution containing the amino acid. Unlike the linear concentration dependences of the apparent molar volume of PyCOOH isomers in a buffer solution, the analogous dependences of ternary systems (PyCOOH–His–buffer) are nonlinear, indicating the formation of a molecular complex between the solutes. Limiting apparent molar expansibilities and their temperature derivatives are determined. Their values suggest that the ordering of the solvent grows in the series of isomers PA → NA → INA upon adding the amino acid to a buffer solution of PyCOOH. It is shown that the limiting apparent molar volumes of transferring PyCOOH from a buffer to a His-containing buffer solution have positive values and grow in the studied range of temperatures. The discussion of the results is based on the dominant types of molecular interactions between the solute and solvent using the Gurney model.

A series of new composites have been synthesized—TiO₂ nanoparticles introduced in the interlayer space of layered mordenite. The effect of the hydrolysis medium of titanium tetraethoxide (water or a mixture of water with ethanol) and hydrolysis time (from 6 to 24 h) on the properties and texture of the composite was studied. Treatment in ethanol leads to partially preserved ordered layered structure of 2D mordenite, presumably due to the slowdown of the hydrolysis of titanium tetraethoxide; this, in turn, provides higher mesoporosity after calcination, created by anatase nanoparticles of ~4 nm in the interlayer space. Immobilization of TiO₂ on the zeolite surface is indicated by the formation of Si–O–Ti bonds.

Hydroxides of nickel-cobalt have been widely employed as supercapacitor electrode materials. However, the shortcomings such as a low specific surface and an unstable structure made it difficult to display an excellent electrochemical performance. To address the said problems, carbon fibers were grown in situ on foam nickel by CVD method to prepare a three-dimensional foam nickel/carbon fiber composite collector, and then nickel-cobalt hydroxides were obtained on the composite current collector by a hydrothermal method with the aim of a superior supercapacitor electrode material (CF/Ni–Co). Effects of anions of metal salts (such as acetate, nitrate, sulfate and chloride) on the morphology, structure and electrochemical performance of the obtained electrodes were investigated. The results suggested that the sample CF/Ni–Co(SO₄) synthesized with nickel sulfate and cobalt sulfate possessed large specific surface area. It also displayed outstanding capacitive performance with a superb specific capacitance of 3675.6 F/g at 1 A/g, a high capacitance retention rate of 70.6% as the current density increased to 15 A/g, and a good cycling stability of 66.4% after 2000 cycles of charge-discharge at 15 A/g, demonstrating CF/Ni–Co(SO₄) with the three-dimensional nickel foam/carbon fiber composite as current collector had great potential for high-performance supercapacitor electrode materials.

The isobaric heat capacities of acetone and its binary aqueous solutions were measured using a heat capacity meter (IT-s-400). The measurements were performed at temperatures from 323.15 to 453.15 K and pressures below 19.6 MPa for acetone and at temperatures from 348.15 to 473.15 K and the same pressures for its solutions, at concentrations of 2.5, 3.5, and 5 wt % acetone. The expanded uncertainty of heat capacity, pressure, temperature, and concentration measurements at a 95% confidence level with a coverage factor k = 2 was estimated at 2.4%, 0.05%, 15 mK, and 0.001, respectively. The results were compared with the literature data in the given ranges of state parameters.

In this paper, we utilize the REFPROP database and establish a new correlation between the temperature and the thermal conductivity of binary saturated refrigerants mixtures. Not only have we achieved a uniform set of parameters for each mixtures group at different ratios, but we have also considered the effect of the temperature T on the thermal conductivity ({{lambda }_{m}}) of the binary saturated refrigerants mixtures. The calculated results are compared with the data from the REFPROP database. The average absolute deviations (AADs) are computed. The majority of AADs are found to be less than 0.5% for all the cases considered. When compared to previously published correlations, this correlation better predicts the thermal conductivity of binary saturated refrigerants mixtures and will be useful for the future researches related to the heat dissipation engineering and engineering technology.

The sorption of triterpene saponins is studied on different brands of active carbon under equilibrium conditions. The effect the surface activity of glycosides has on the course of the curves is established. Sorption isotherms are assessed using a formal approach based on selecting the sorption equations (Langmuir, Freundlich, BET, Redlich–Peterson) that describe the obtained dependences as closely as possible. Thermodynamic characteristics of the given process (energy of sorption, enthalpy, and entropy) are calculated using sorption curves in the coordinates of the Langmuir equation.

The C₃N₄/AlFeO₃ photocatalysts were synthesized successfully via a sol-gel route and low temperature calcination process. When C₃N₄ is coupled with AlFeO₃ to form a special heterojunction, the crystal structure, composition and optical band gap of the main lattice phase are not changed. However, its surface morphology, optical absorption coefficient and photocatalytic activity are greatly improved compared with pure C₃N₄ and AlFeO₃. Photocatalytic experiments confirmed that the C₃N₄/AlFeO₃ photocatalyst showed high photocatalytic activity for degradation of methyl orange under visible light irradiation, and its degradation rate was 9.40 times that of C₃N₄ and 5.13 times that of AlFeO₃. The optimal catalyst content, dye concentration and pH value are 1 g/L, 20 mg/L and 5, respectively. Capture and stability experiments confirmed that the C₃N₄/AlFeO₃ photocatalyst is recyclable, and holes, hydroxyl radicals and superoxide radicals are the main active species in the photocatalysis process.

In the current study, the most stable optimized structure of the named compound 5-(furan-2-ylmethylidene) thiazolo[3,4-a] benzimidazole-2-thione (FThBZ) was determined using the B3LYP/6-311++G(d,p) basis set. The nature of molecular interactions between molecules in the crystal via different type of bonds was investigated using Lattice Energy analysis and non-covalent reduced density gradient (NC-RDG) and Fukui functions are performed to study the chemical reactivity of the compound. The dipole moment values, first and second order polarizability and hyperpolarizability of the title compound were calculated. A symptom of Alzheimer’s is the appearance of amyloid plaques, or senile plaques: made up of aggregates of beta-amyloid peptide between nerve cells. To overcome this effect, there is a need for a potent and effective inhibitor that inhibits the proper functioning of amyloid precursor protein (APP). In this regard, we conducted an in silico docking and molecular dynamics simulation study.