This study explores the synthesis of activated biochar (ABC) from date pits and CuO-ABC nanocomposite for the adsorption elimination (AE) of model and commercial fuels. Outcomes deduced from FESEM, TEM, EDX, XRD, and the N2 adsorption-desorption isotherms confirmed the microporous structures of both adsorbents. The SABET as well as pore diameter of the ABC were, respectively, 765.52 m2/g and 1.79 nm, while the SABET and pore diameter of CuO-ABC nanocomposite were, respectively, 621.57 m2/g and 1.99 nm, referring to the micro-porous structures of both adsorbents. The maximum AE % of 200 mg/L DBT solution by the ABC was 98.09 % using 0.20 g of the ABC at 30 degrees C for 25 min. In comparison, the highest AE % of 200 mg/L DBT solution over the CuO-ABC nanocomposite was 99.24 %, achieved with 0.15 g of nanocomposite at 30 degrees C for 20 min. The isothermal and kinetic studies revealed that the Langmuir adsorption isotherm and the pseudo-2nd-order kinetic model best described the adsorption of DBT. Both adsorbents exhibited sustained activity across five consecutive cycles. The S-content of real gasoline was reduced to 80.12 % and 84.22 % using 0.60 g of both adsorbents at 30 degrees C for 120 min. This work presents cost-efficient adsorbents for desulfurization of a model desulfurization system and actual fuel oils at the industrial scale.
The purpose of this study was to investigate the influence of electron vacancies on the superconducting properties of transition metal sulfide compounds (Cr, Cu) to evaluate their potential in increasing the critical transition temperature. This study reviewed the theoretical models and experimental data on superconductivity based on copper, chromium, and sulfide compounds. Synthesis and stability data for the FeCuS2 compound were used for analysis, and temperature coefficients for various superconducting materials, including oxides and sulfides, were calculated. The study considered the compound Fe2Cu3S6, which exhibited superconductivity at 89 K, with a narrow transition interval and evidence of ferromagnetic ordering. Experimental data indicated the influence of electron vacancies in the crystal lattice on conductivity, which favors the occurrence of the superconducting state. Model calculations revealed a linear dependence between the number of electron vacancies Qelv and the transition temperature Tc in a series of sulfide systems, including Cr-Cu-S. This gives prospects for the search for superconductors with high transition temperatures. Comparison with other materials, such as oxide compounds, revealed that sulfides can exhibit greater critical superconductivity temperatures. The practical significance of the study lies in the development of new approaches to the design of sulfide compounds that promote the generation of a superconducting state at room temperatures.
We report the fabrication of catalytically active AgNPs/Cu oxygen reduction cathodes using the method of galvanic replacement of copper with silver in K[Ag(CN)(2)] solutions. It was shown that the formed AgNPs with an average size < 50 nm are uniformly distributed on the copper surface, and their content depends on the concentration of the cyanocomplex and the duration of the GR process. It was determined that in a broad silver concentration range (0.02-0.86 at. %) on the copper surface, the AgNPs/Cu cathodes exhibit 15 % higher ORR activity than silver cathodes, and exhibit superior parameters E-onset (by similar to 0.02 V) and E-1/2 (by similar to 0.05 V). The testing results in alkaline zinc-air fuel cells showed that the discharge voltage of cells based on AgNPs/Cu cathodes rivals that of the cells based on silver cathodes.
The present study investigates the relevance of producing fluorine-containing polymers based on tetrafluoroethylene (TFE) and TFE-hexafluoropropylene (HFP) compositions. It has been demonstrated that the byproducts resulting from the degradation of these polymers are hazardous, and their recycling or disposal is challenging. A thorough analysis of contemporary methods of polytetrafluoroethylene (PTFE) recycling has been conducted, indicating that chemical processing of PTFE results in the generation of substantial quantities of monomers, including TFE, HFP, and cyclooctafluorobutene. These monomers can be utilized in the synthesis of new fluoropolymers, contingent upon the assurance of sufficient purity. The article puts forward a novel absorption-based method for the purification of HFP and TFE from fluorinated hydrocarbon compounds. It has been established that ethyl acetate (EA) is a selective solvent for TFE, HFP, and the associated fluorinated hydrocarbons. The solubility of all components of the gas mixture in EA was investigated within the temperature range of 263-313 K. An analysis was conducted on the temperature dependence of Henry's law constant during dissolution, the results of which indicated an increase in the solubility of fluorinated organic gases in EA with an increase in temperature. The parameters of the absorption purification process for perfluoromonomers were determined, thereby enabling the reduction of fluorinated hydrocarbon compounds by two orders of magnitude and yielding monomer products with a main substance content of no less than 99.99 vol. %.
This article presents the results of a comprehensive study on the chemical composition and antioxidant activity of aqueous-ethanolic extracts obtained from Persea americana Mill. (avocado) seeds using extractants of different concentrations (40 % and 70 %) and raw materials in different states (fresh and dry). Thin-layer chromatography confirmed the presence of ascorbic acid as well as phenolic compounds in all extracts, including gallic acid and quercetin. The total phenolic content was determined spectrophotometrically using the Folin-Ciocalteu method, while the total flavonoid content was measured by the aluminum chloride colorimetric assay based on a linear regression equation derived from the quercetin calibration curve (expressed in QE). Quantitative analysis showed that the total phenolic content ranged from 1.204 to 1.861 mg/g, flavonoids-from 2.663 to 3.395 mg/g, and amino acids (determined by the ninhydrin reaction)-from 0.054 to 0.140 % in terms of alanine equivalent. The highest phenolic content was found in the 40 % extract from dry seeds, whereas flavonoids were more efficiently extracted with 40 % ethanol from fresh raw materials. Modeling of lipid peroxidation and protein oxidative modification processes in vitro revealed pronounced antioxidant activity in all extracts, particularly in the 40 % extracts from dry seeds, which reduced the levels of thiobarbituric acid-reactive substances by 44.3 % and protein carbonyl groups by 73.1 % (p <= 0.001). These findings indicate the high antioxidant potential of Persea americana seeds, suggesting their promise as a natural source of antioxidants for pharmaceutical, cosmetic, and food applications.
