Russian Journal of Applied Chemistry最新文献

One of the most significant environmental problems on the globe is still the presence of contaminants in natural water. This is due to a significant rise in freshwater demand and a water crisis in arid and semiarid regions, driven by population growth, urbanization, industrialization, and agricultural activities. The current study’s objective was to evaluate the water quality adequacy both upstream and downstream of the Haditha Dam in the western region of Iraq. In this study, 14 parameters were assessed and examined to evaluate the water quality on both sides of the Haditha Dam (upstream & downstream), including potassium K, carbonate CO₃, bicarbonate HCO₃, chloride Cl, sulfate SO₄, calcium ca, nitrate NO₃, sodium Na, magnesium Mg, electrical conductivity EC, pH, total soluble salts TSS, hydrogen sulfide H₂S, and total hardness. This research looks at data on water quality that were gathered from both banks of the Euphrates River during four years by collecting ninety-six samples. The established methods were applied to the parameters under examination. The outcomes were contrasted with The World Health Organization (WHO) and Iraqi water quality criteria. This research aids in the strategic and prudent management of water resources, potentially utilizing them for drinking water and agriculture. Data analysis indicates that all chemical constituents comply with Iraqi water quality regulations.

In this study, a series of new O,O-dialkyl(1-hydroxy-1-(4-nitrophenyl)ethyl)phosphonates containing various substituents on the phosphorus atom were designed. All synthesized compounds demonstrated antibacterial and antifungal activity against gram-positive bacterial strains B. cereus and S. aureus. It was found that compounds 2–5 exhibit antifungal activity comparable to the control compound Naftifine hydrochloride.

The effect of integration iron cations into zeolite ZSM-5 on the physicochemical properties of the material and the direction of transformation of n-dodecane and 2-methylthiophenes (5000 ppm S) in catalytic cracking was investigated. The integration of iron led to a significant increase in the total acidity of zeolites with SiO₂/Al₂O₃ ratios of 23 and a slight increase for zeolites with SiO₂/Al₂O₃ ratios of 80. For both types, the volume of micropore remained unchanged. It was found that modifying zeolite ZSM-5 with SiO₂/Al₂O₃ ratios of 23 with iron increased the yield of aromatic compounds from 27.1 to 38.1 wt %, and light olefins from 22.5 to 30.3%. The content of sulfur compounds decreases by 44% with an increase in the proportion of iron oxide in zeolite ZSM-5 with SiO₂/Al₂O₃ ratios of 23.

The primary objective of this study was to employ an eco-friendly approach for the synthesis of silver oxide nanoparticles (AgO NPs) using aqueous extracts derived from lemon (Citrus limon) leaves. This method offers numerous advantages, including biocompatibility, environmental sustainability, and resilience, making it an attractive alternative to conventional synthesis techniques. The synthesized AgO NPs underwent comprehensive analysis using Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, Dynamic light scattering and Scanning Electron Microscopy-Energy Dispersive X-ray Analysis. Furthermore, the antioxidant potential of the synthesized AgO NPs was evaluated using 2,2-diphenyl-1-picrylhydrazyl and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid assays. These assays provide insights into the ability of the nanoparticles to scavenge free radicals, highlighting their potential applications in biomedical and environmental settings. Overall, the comprehensive characterization and evaluation of the synthesized AgO NPs underscore their potential as versatile nanomaterials with promising antioxidant potential, paving the way for further exploration in various fields of research and application.

The destruction of polypropylene (PP) at low pressure in a nitrogen flow with the aim of preparation of oligopropylene macromonomer (OPMM) was carried out. The influence of various process factors (temperature, pressure) on the yield of the purposeful product was studied and the optimal parameters of thermal destruction of polypropylene were determined. It was shown that the highest yield is achieved at temperature of 340°C and pressure of 500 mmHg. Unlike the known ones, in the proposed method, the molecular weight (MW) of the macromonomer can be simultaneously adjusted with varying temperature and pressure. It was shown that timely removal of the reaction product from the reactor favors the prevention of the secondary reactions (decomposition, branching) and preparation of the macromonomer with the narrow molecular weight distribution. The radical copolymerization reaction of maleic anhydride (MA) with oligopropylene macromonomer was carried out, the regularities of the copolymerization reaction, the composition and structure of the obtained products were revealed. The the relative activity values of the oligopropylene macromonomer (r₁ = 0.052) and maleic anhydride (r₂ = 0.0035) during their copolymerization were determined by the Fineman-Ross method. The microstructure parameters were calculated for samples of the copolymer of the oligopropylene macromonomer with maleic anhydride obtained under various conditions. It was detected that during the copolymerization of the macromonomer polypropylene+maleic anhydride pair in the presence of benzoyl peroxide (BP), the copolymer macromolecules of an alternative structure are formed. Depending on the copolymerization conditions, the average molecular weights of the obtained copolymers are oscillated within the range of 12970–19750 (M_w) and 8470–14500 (М_n).

The copper doped polycrystalline Cu_xNi_1–xMn₂O₄ (CNMO), Cu_xZn_1–xMn₂O₄ (CZMO), and Cu_xCo_1–xMn₂O₄ (CCMO) with (0.05 ≤ x ≤0.55) manganites were synthesized by chemical co-precipitation route. The incorporation of copper in place of nickel, zinc and cobalt in all the three series of samples respectively change significantly the lattice parameters, crystal size, microstrain and dielectric properties at various frequencies. With the increase in copper the lattice parameter and crystallite size decreases for CNMO, CZMO samples and increases for CCMO samples respectively. The dielectric constant increases from 35 to 950, 70 to 410 for CNMO, CZMO samples and (7 to 20) × 10³ for CCMO samples at low frequency (10 Hz) with the increment in copper doping.

The work aims to determine the kinetic parameters of reactions for production of light olefins via catalytic cracking reactions of C₄–C₆ n-alkanes based on the energy characteristics of the transition state using quantum chemical calculations. Cracking reactions of C₄–C₆ n-alkanes proceed via protolytic mechanism on the Brønsted acid sites of zeolite-containing catalysts. For kinetic studies in this work, the thermochemical parameters of the intermediate stages, including hydrocarbon adsorption and transition state were determined, then the activation energies and rate constants were determined over the temperature range of catalytic cracking process from 773–903 K (500–630°C). The results showed that DFT method in combination with B3LYP and ωB97X-D functionals, and 3-21G basis demonstrated quite high accuracy in determining thermochemical parameters, including enthalpy, entropy and Gibbs free energy at both energetic levels of adsorption and transition state. Then, modeling continued by calculations of activation energies and rate constants of reactions. Obtained kinetic parameters made it possible to determine the reactivity of hydrocarbons with different chain length. It was obtained that the rate constants of butane cracking reactions with the formation of ethylene are 54–90 times higher than the formation of propylene. The rate constants of pentane cracking reactions with the formation of butylene are on average 5 times higher than the formation of propylene. The rate constants for hexane cracking reactions with the formation of butylene are 2.9–3.7 times higher compared to the formation of propylene.

The green synthesis of silver nanoparticles (AgNPs) has garnered significant attention due to its eco-friendliness, safety, and time efficiency. This study explores the ultrasound-assisted synthesis of AgNPs using an aqueous extract of Hopea odorata (HO) and evaluates their antibacterial properties. The reaction conditions, silver ion concentration, ultrasound amplitude, and time, were optimized using UV-Vis spectroscopy, achieving nanoparticle synthesis in just 30 min. Comprehensive characterization revealed ultra-small HO-AgNPs with an average size of 2.8 nm, confirmed by SEM, TEM, FTIR, XRD, DLS, and zeta potential analyses. FTIR results suggested phenolic compounds in the extract act as stabilizing and reducing agents, while the highly negative zeta potential (–40.9 mV) indicated excellent stability. Antibacterial tests demonstrated strong activity against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa, with the highest efficacy against P. aeruginosa. These findings highlight HO-AgNPs as promising ultra-small nanoparticles with potent antimicrobial potential.

This study investigates the influence of carbon nanotubes (CNTs) and silicon carbide (SiC) powder on the structural and mechanical properties of an epoxy-anhydride binder. The primary objective was to elucidate the modification mechanisms of the polymer matrix upon filler incorporation and evaluate their impact on the material’s thermoelastic characteristics. A key challenge involved establishing correlations between filler-induced structural changes and the composit’s viscoelastic behavior. X-ray diffraction analysis revealed that SiC addition reduces the intensity of the first diffusion peak by 23% with concomitant peak broadening, indicating decreased atomic clustering. Conversely, CNT incorporation increased the z₁/z₂ ratio by 15%, accompanied by expansion of the most probable interatomic distances (r₁) to 2.8 Å. Dynamic mechanical analysis demonstrated that SiC enhances the elastic modulus by 20.8% at 0.75 wt % concentration through formation of additional crosslinking nodes and cluster interactions, while maintaining property stability within the 40–115°C range. Both fillers extended the relaxation temperature interval by 5–7°C, improving damping capacity through the creation of “friction centers,” as evidenced by 18% increases in tan δ peak heights with unchanged peak widths. Radial distribution functions revealed distinct structural modifications: SiC reduced r₁ to 2.1 Å, indicating denser packing and lower curing energy, while CNTs produced a less dense structure with higher activation energy. These findings demonstrate that filler modification of the epoxy matrix not only alters rheological properties but also induces nanoscale phase transitions, enabling rational design of composites with desired thermomechanical performance.

New hybrid palladium catalysts on substrates of γ-aluminum oxide and hyperbranched polyaminoethylene carbonates of the second and third generations have been synthesized. The catalysts were synthesized in several stages, firstly modification of γ-aluminum oxide with dimethyl carbonate was carried out. In the second stage, hybrid composites were synthesized by reaction of modified γ-aluminum oxide with hyperbranched polyaminoethylene carbonates of the second and third generations. In the next stage, palladium complexes were obtained by reacting the hybrid composites with palladium chloride. The structures and spherical morphologies of the particles of the obtained compounds were confirmed by infrared spectroscopy (IR), X-ray diffraction analysis (XRD), confocal laser scanning (CLSM) and optical microscopy. The pore characteristics of the Pd(II) complexes were determined by nitrogen adsorption/desorption. Pd(II) palladium complexes reduced in hydrogen flow to Pd(0) nanoparticles were utilized in the selective hydrogenation reaction of α-methylstyrene to cumene. The hybrid palladium catalysts on second and third generation γ-aluminum oxide and hyperbranched polyaminoethylene carbonate substrates showed high catalytic activity with activation energies E_a = 45.2 and 46.3 kJ mol^–1 in the temperature range from 43 to 73℃ and atmospheric pressure. The results indicate promising applications of the new hybrid catalysts for the hydrogenation of unsaturated compounds.