Russian Journal of Applied Chemistry最新文献

The hydrogenation of CO₂ to hydrocarbon compounds is a promising approach for CO₂ resource utilization and environmental sustainability. Nevertheless, its efficient conversion to valuable chemicals remains a challenge because of the substantial activation energy barrier associated with CO₂. In this work, yInO_x@NPC materials with varying In contents loaded on N,P-doped carbon (NPC) were prepared through the adsorption of In³⁺ on the amino-phosphoric acid chelating resin D418, followed by carbothermal reduction. Beta zeolite was hydrothermally synthesized, and a series of (Zn,Al)Beta–S_x samples with diverse acidity modified subsequently by Zn isomorphous substitution were prepared via the post-synthesis method. The influence of the In content and electronic properties of carbon-confined yInO_x@NPC, as well as the acidity of the Zn-modified Beta zeolite on the catalytic performance of CO₂ hydrogenation over yInO_x@NPC/(Zn,Al)Beta–S_x tandem catalysts obtained by mixing the powders of yInO_x@NPC and (Zn,Al)Beta–S_x was comprehensively investigated. The results revealed that 1InO_x@NPC/(Zn,Al)Beta–S₂ with the maximum oxygen vacancy density, milder Brønsted acid strength and higher Lewis acid strength enhanced the conversion capability of CO₂ and methanol intermediates, as well as increased the selectivity toward aromatics and C₄ hydrocarbons. Under the optimized reaction conditions, C₄ hydrocarbons selectivity of 41.8% and aromatics selectivity of 42.3% were obtained under CO₂ conversion of 18.8%, and a minimum selectivity of 8.6% for unwanted CO was achieved. The present work provides valuable insights into the development of tandem catalysts with high selectivity for C₄ hydrocarbons and aromatics due to the synergistic catalysis of metal and acid sites.

Parabens are commonly used as preservatives in numerous personal care products and foods to prevent the growth of microorganisms. Parabens play vital role as antimicrobial, preservative, and flavoring agents hence are often used in cosmetic, pharmaceutical and flavor products. The high concentrations of parabens can cause sever health issues, hence the methyl and propyl paraben levels in cosmetics are restricted and all other parabens banned. Thus, a simple, rapid, and ecofriendly dispersive liquid-liquid microextraction method based on solidification of a floating organic drop (DLLME-SFO) technique has been developed for the extraction of methyl and propyl parabens from cosmetic cream. The separation and quantification of these parabens are performed using gas chromatographic flame ionization detector method. The extraction solvent, dispersive solvent, solvent volumes, diluent, gas chromatography (GC) column and carrier gas are optimized. The method is validated according to the ICH guideline for specificity, precision, recovery, linearity, and limit of detection. This method achieves accuracy of 100.727% (±0.002%) and 98.713% (±0.003%) for methyl and propyl paraben, respectively. The present method is simple, rapid and accurate for quantification of parabens hence valuable, reliable, and very suitable to be applied in routine quality control laboratories.

This study investigates the photocatalytic decolorization of Acid Yellow 36 dye using sintered ZnFe₂O₄ powder prepared at 500–900°C for 4 h. Photocatalytic experiments were conducted under artificial illumination using a Philips 250 W light source with an intensity of 1.48 × 10^–7 Ens s^–1. The decolorization process followed pseudo-first-order kinetics. Optimum conditions for decolorization were determined as an initial dye concentration of 50 mg/L, a ZnFe₂O₄ dose of 150 mg/100 mL, and an initial solution pH of 6.75. Under these conditions, a maximum dye removal efficiency of 88.18% was achieved within 100 min at 30°C. Increasing the reaction temperature enhanced the photocatalytic activity, with a positive enthalpy change (ΔH) of 20.55 kJ mol^–1 and a low activation energy of 22.61 kJ mol^–1. Additionally, the Fenton reaction using ZnFe₂O₄ nanopowder further enhanced the photodecolorization efficiency, demonstrating its potential as an effective photocatalyst for wastewater treatment.

Glass-like epoxy-titanium oxide composites were obtained using amine curing and sol-gel method for the formation of nanofiller from titanium tetra-n-butoxide directly in the polymer binder. As a polymer matrix of the composites, the product of polycondensation of low-viscosity epoxy resin ST-3000 and polyetheramine Jeffamine T-403 was used. The titanium dioxide content in the composites was 0.5–10 wt %. The structure of the obtained composites was studied by Raman spectroscopy and electron microscopy, and a detailed thermomechanical analysis of the samples was performed. The titanium oxide nanofiller forms a three-dimensional network in the organic polymer matrix, and such an inorganic framework reinforces the polymer. With an increase in TiO₂ concentration, the temperature of the beginning and the temperature of completion of the transition of the composites to a highly elastic state significantly increase. The mass-fractal structural organization of titanium dioxide in the composites determines the lower deformability of the samples. Interphase transition layers with different segmental mobility were detected in the structure of the composites. In these layers, during the formation of epoxy-titanium oxide composites, filler/matrix interaction occurs with the formation of chemical covalent bonds. The features of the composites’ structure affect the operational properties, in particular, the protective properties of coatings based on them. It was established that thin composite coatings can provide corrosion resistance of 315 kΩ cm² on the surface of the D16 aluminum alloy. The efficiency of corrosion protection of the substrate was 70–90%, depending on the filler concentration in the coatings.

The nozzle blades of a gas turbine engine (GTE) are an important part of an aircraft engine. During operation, the nozzle blades are exposed to high temperatures, mechanical loads, sulfide and salt corrosion. Due to the influence of aggressive factors, carbon deposits, metal oxides and microcracks form on the surface of the blades of the gas turbine engine. To restore the performance characteristics of the blades, it is necessary to clean the surface of the blades from aluminum, titanium, tungsten, chromium, and nickel oxides. Based on the analysis of literature sources, it is shown that many detergents are not able to remove these oxides with high chemical resistance from the surface of the blades. In the article, halide-containing substances such as hydrogen fluoride gas, hydrofluoric acid, and hydrochloric acid were used to clean the blades from metal oxides. The main purpose of this work was to study the efficiency of cleaning the surface of the GTE nozzle blade with halide-containing compounds from carbon deposits and stable metal oxides of aluminum, titanium, tungsten, chromium, and nickel. The composition of the material used in the study and the analytical tools used to determine the surface composition of a sample of a GTE nozzle blade made of an alloy of the KHN54KVMTYUB brand are described. The methodology and conditions of the processes of exposure to gaseous hydrogen fluoride, hydrofluoric and hydrochloric acids are considered. The features of the effect of halide-containing substances on stable metal oxides on the sample surface have been studied. It was found that hydrogen fluoride gas reacts actively with aluminum and tungsten oxide, thereby destroying the basic structure of the oxide film. Hydrofluoric acid also reacts with the components of the KHN54KVMTUB alloy, accompanied by a thinning of the oxide layer and a decrease in the oxygen content on the surface. When cleaning with hydrochloric acid using ultrasonic treatment, depressions appeared on the surface of the blades. Thus, halide-containing reagents actively react with the surface of the KHN54KVMTUB alloy, which helps to clean the blades from the oxide layer.

The article considers the features of polyamide-6 modification with additives based on molybdenum disulfide, which significantly expands the scope of its application. However, polymer modification not only alters the target properties but may also affect other characteristics, sometimes negatively. The main task for developers of composite material is to select a balanced composition to achieve the desired goal—obtaining an antifriction, wear-resistant composite. The study presents a brief analysis of the effect of molybdenum disulfide on the overall properties of the polymer composites based on a literature review of publications from the last 5–7 years (16 sources, including cross-references). The effect of molybdenum disulfide on the physico-mechanical and technological properties of polyamide-6 has been investigated. In addition, various approaches to the creation of polymer composites are discussed. Initially, a fairly wide range of additive concentrations was studied and a narrow sector of its rational and effective use was determined. In the second stage of the study, the approach to polymer modification was changed. A modification scheme focused on large-scale production of polymer products was used. Based on the results of preliminary studies, international experience in this area was analyzed. It was noted that similar effects were observed when creating nanocomposites using modified molybdenum disulfide samples, but the general behavior of the polymer material and the achieved characteristics are different. The study highlights the challenges in producing MoS₂-based composites via direct mixing of components in a twin-screw extruder and proposes a method for their production using concentrates. The behavior of polymer compositions in the areas of ultimate deformations were investigated, revealing an increase in tensile strength and a change in the destruction mechanisim with hypotheses proposed regarding their nature. It was noted that the zone of ultimate deformations could be a subject of further research and is of interest in the context of forming highly oriented states in polyamide-6 composites.

The kinetics of radical polymerization of perfluoropropylvinyl ether (PFPE) was investigated in the presence of a radical initiator at pressures of 264–1056 MPa and temperatures of 323–368 K. Activation energies were determined at different pressures: at P = 10.56 kbar E_act = 135.4 kJ/mol (32.4 kcal/mol), at P =7.04 kbar E_act = 108.3 kJ/mol (25.9 kcal/mol). The activation volume of the total polymerization rate ΔV₀^≠ = –14.6 cm³/mol was determined at T = 353 K. The activation energies of the material initiation were calculated at different pressures [at P = 10.56 kbar, E_i = 123.3 kJ/mol (29.5 kcal/mol), at P = 7.04 kbar, E_i = 88.3 kJ/mol (21.1 kcal/mol)].

Cathodic exfoliation graphene (GN) reinforced epoxy resin (EP) composite materials were prepared by the solution blending method. Elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR), Raman spectra (Raman), X-ray diffraction (XRD) and scanning electron spectroscopy (SEM) results demonstrate that GN nanosheets are well exfoliated in organic solvents and dispersed in EP. The tensile and flexural properties of the composite materials were tested using a universal tensile machine. Results showed that the added GN can significantly improve the tensile and flexural properties of composites. When the amount of GN loading is 1.0 wt %, the tensile strength, elongation at break, flexural strength and flexural modulus of GN/EP composite materials can be up to 96.77 MPa, 5.61%, 115.38 MPa, and 3507.8 MPa, respectively. The possible mechanism is that good interfacial bonding between the GN and matrix is account for the observed improvements in tensile and flexural properties.

A series of novel N-(3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-2-(4-phenyl-5-(arylphenyl)-4H-1,2,4-triazol-3-ylthio)acetamide derivatives were synthesized, characterized, and evaluated for their cytotoxic potential. The synthesis, monitored by thin-layer chromatography (TLC), involved multiple steps, and the compounds were purified by recrystallization. The structures were confirmed using spectroscopic techniques, including NMR, Mass, and IR spectroscopy. The compounds were tested against MCF-7 (human breast cancer), HOP-62, and A-549 (human lung cancer) cell lines. Compound 6b emerged as the most potent compound, displaying low LC50, TGI, and GI50 values across all cell lines. Other derivatives, such as 6a and 6c, showed moderate activity, while some exhibited negligible effects. These findings indicate that 6b holds strong potential as an anticancer agent, while further optimization may enhance the efficacy of other derivatives.