The study of the dissolving ability of acidic compositions based on surfactant, polyols, adduct of inorganic acid and carbonic acid diamide in relation to terrigenous and carbonate rocks and colmatating substances, was carried out. The use of the studied acidic compositions had a different solvent effect on rocks of different types. The most pronounced solvent ability was shown by the composition GBC-F. The studied compositions also decreased colmatation in relation to inorganic colmatants.
Human activities lead to the contamination of soils, natural water bodies, and, consequently, food products with various toxic compounds, including herbicides. Detonation nanodiamonds (DNDs) are promising materials for the creation of enterosorbents and purification of aquatic environments from various toxicants. The study utilized samples of diamond-containing charge (ASH-TH) and detonation nanodiamond (DND-TH), synthesized by detonating explosives (TNT-hexogen). Energy-dispersive X-ray spectroscopy, EPR spectroscopy, scanning electron microscopy, Fourier-transform IR spectroscopy, and low-temperature nitrogen adsorption were used to characterize the samples. The sorption properties of ASH-TH and DND-TH samples were studied for one of the most common and dangerous herbicides, glyphosate. Experiments were conducted in aqueous media at pH 2 and pH 8, simulating conditions in the mammalian gastrointestinal tract. It was found that the studied samples of ASH-TH and DND-TH had different sorption capacities for glyphosate, with the former exhibiting superior sorption properties. The obtained results demonstrate the potential of using detonation nanodiamonds as glyphosate adsorbents.
The efficiency of different approaches to iota-carrageenan sulfation with sulfamic acid (in the presence of urea over Amberlite (R) and Pyrolite (R) catalysts), sodium pyrosulfite, sodium sulfite, and ammonium sulfamate has been compared. It has been established that the highest product yield (79.25 %) and the maximum sulfur content (14.2 %) hare obtained in the processes involving sulfamic acid and an urea activator in a 1,4-dioxane medium at a process temperature of 90 degrees C and a process time of 3 h. The poorest results have been obtained when the sulfation process occurred with the participation of sodium sulfite (yield 4.25 % and S content 7.7 %) and sodium pyrosulfite (yield 10.5-12.1 % and S content 11.5-11.6 %). The synthesized derivatives have been then characterized by the advanced analysis that included several physical and chemical techniques: Fourier-transform infrared spectroscopy, X-ray diffractometry, TG-DSC simultaneous thermal analysis, atomic force microscopy, and gel permeation chromatography. It has been demonstrated that sulfation noticeably enhances the number of sulfo groups and reduces the molecular weight Mw (from 682547 to 47108 g/mol) and the degree of polydispersity (from 4.61 to 5.83) and induces the polysaccharide structure amorphization. The reported results are of great importance for the creation of powerful techniques for modifying polysaccharides in the way of synthesis of novel materials with required biological, physical, and chemical characteristics.
New methods for the synthesis of organic and carbon composites based on chitosan and aerogel from birch pulp are proposed. The obtained chitosan-cellulose composites have a spongy structure (the size of the cavities is from 50 to 70 microns), a low density (0.041-0.046 g/cm(3)) and a poorly developed meso-macroporous structure. The effect of additives of modifying agents (tannins of larch bark and Cu(Ac) on the porous structure and thermochemical properties of biocomposites has been established. The introduction of tannins reduces the average pore size and increases the specific surface area of the biocomposite. Carbon composites were obtained by carbonation of chitosan-cellulose biocomposites at a temperature of 600 degrees C. The resulting carbon composites have a poorly developed porous structure, and the addition of tannins increases the specific surface area of carbon composites from 1 m(2)/g to 7 m(2)/g and helps reduce the size of mesopores to 10.7-12.4 nm. The porous structure of carbon composites was developed by their thermal alkaline activation with NaOH at 800 degrees C. The surface of carbon composites increases by 2-3 orders of magnitude after activation and reaches 1160 m(2)/g for a sample containing an additive of tannins. The sample doped with copper acetate has the lower specific surface area (588 m(2)/g). Activated carbon composites are micro-mesoporous materials. The ratio of micropores and mesopores in them varies depending on the chemical composition of the initial biocomposite. The properties of the obtained carbon composites based on chitosan and cellulose, such as high specific surface area, adjustable porous structure, low density, and the possibility of chemical modification, open up prospects for their use as catalysts, catalyst carriers, adsorbents.
Stabilizers are widely used in polymer products to preserve their performance characteristics by preventing degradation caused by environmental factors. The expanding applications of polymer materials drive the need for the development of effective stabilizers and the improvement of existing production technologies. A current trend in stabilizer chemistry is the synthesis of multifunctional antioxidants that operate through various mechanisms of polymer thermo-oxidative degradation inhibition. In this study, a multifunctional antioxidant-tris(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propyl)phosphite-was synthesized. The compound contains several ageing inhibition centers: a phosphorus(III) atom and sterically hindered phenolic groups. The target compound was obtained in high yield via the reaction of 2,6-di-tert-butyl-4-(3-hydroxypropyl) phenol with phosphorus trichloride in an inert atmosphere in the presence of triethylamine. The structure of the resulting product was confirmed by IR and 31P NMR spectroscopy. The antioxidant efficiency of the synthesized compound was evaluated based on its peroxide radical scavenging ability in a model reaction with 2,2-diphenyl-1-picrylhydrazyl (DPPH). Experimental results showed that the synthesized product reacts with DPPH at a higher rate constant (k = 3.786 +/- 0,189 & times; 10(-5) s(-1)) than the industrial antioxidant Irganox 1010 (k = 3.029 +/- 0,151 & times; 10(-5) s(-1)). The effectiveness of tris(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propyl)phosphite as a thermal antioxidant for polypropylene was also assessed. It was demonstrated that the synthesized compound exhibits a stabilizing effect comparable to that of the commercial synergistic antioxidant blend Irganox B 225 (a 1:1 mixture of Irganox 1010 and Irgafos 168).
To select salt hydrates as the basis of phase change heating storage materials for specific applications, it is necessary to simultaneously take into account about 30 properties, including environmental, economic aspects, as well as stability parameters and physico- chemical properties. Chemometric methods, in particular, the principal component method and SIMCA, were used to identify the structure- property relationship of the use of salt hydrates as heating storage materials. Based on the analysis by these methods of the multidimensional classification of the properties, structure and composition of salt hydrates, the list of criteria for the selection of hydrates has been reduced to 10. Based on these criteria, salts have been selected as promising hydrates for obtaining phase change heating storage materials based on them: Ca(NO3)(2)& centerdot;4H(2)O, CaCl2 & centerdot;6H(2)O, Zn(NO3)(2)& centerdot;6H(2)O, CH3COONa & centerdot;3H(2)O, MgCl2 & centerdot;6H(2)O and Mg(NO3)(2)& centerdot;6H(2)O.
Transformations of industrially available cyclohexanone towards potentially pharmacologically active, according to the Pass Online program, nitrogen-containing compounds using the Prins reaction as the fundamental reaction are proposed. The antioxidant activity of the synthesized compounds was studied using a kinetic model of the initiated oxidation of 1,4-dioxane. It is shown that some of the tested compounds possess antioxidant properties
This study aims to enhance the thermal and moisture insulation properties of asphalt by incorporating eco-friendly organic and inorganic additives. Physical modification was performed using sawdust and calcium carbonate (CaCO3), while aluminum chloride (AlCl3) was used as a catalyst for chemical modification. Key tests included thermal conductivity, water absorption, FTIR spectroscopy, and mechanical property evaluations. Thermal conductivity decreased from 0.243 W/m & centerdot; degrees C (original asphalt) to 0.124 W/m & centerdot; degrees C in the chemically modified sample. Water absorption also significantly declined in modified specimens, particularly those containing CaCO3 and AlCl3.These modifications improved insulation efficiency and reduced permeability. The use of natural, low-cost additives enhances environmental sustainability, making the modified asphalt suitable for infrastructure applications in severe climates.
The cyclocondensation of 3-hydroxyimino-1-methoxypentane-2,4-dione with methyl-, ethyl-, propyl-, isopropyl-, and phenylhydrazine was investigated for the first time, yielding promising 4-nitrosopyrazoles with a methoxymethyl substituent at the 3-or 5-position. The reaction affords two regioisomeric 3(5)-methyl-4-nitrosopyrazoles, with the 3-methyl-substituted isomers predominating (ratios ranging from 1.25:1 to 5.7:1). Total yields of the regioisomers range from 27 to 75 %, depending on the hydrazine structure. The synthesized compounds were characterized using IR, NMR, UV-Vis spectroscopy, and GC-MS.
The influence of various dispersed fillers (talc, organoclays Cloisite 10A, Cloisite 30B, diatomite NDP-D-400, and wollastonite MB-10-96K) on the vulcanization characteristics of the rubber compound, physico-mechanical, performance and dynamic properties of rubber for rail fastening gaskets was studied. It was shown that equal-weight replacement of kaolin with fillers (except organoclays) results in minor changes in maximum torque and increases in minimum torque and vulcanization onset time. Moreover, the optimal vulcanization time for the rubber compound containing kaolin is greater than its values for the rubber compound variants containing the other fillers studied. It was found that replacing kaolin with organoclays leads to minor increases in tensile strength and tear resistance. Vulcanizates containing all fillers exhibit a decrease in elongation at break compared to the vulcanizate containing kaolin, while their hardness and rebound elasticity are little affected by the nature of the fillers used. The vulcanized rubber containing organoclay Cloisite 30B exhibits the smallest changes in elastic-strength properties and hardness after thermal-oxidative aging in air and exposure to SZhR-1, which is also characterized by minimal changes in mass after exposure to industrial oil I-20A, standard hydrocarbon liquid SZhR-3 and distilled water, as well as improved dynamic properties.
A sample preparation method for solids from atmospheric aerosols collected on membrane acetate filters is proposed for element determination by ICP-MS aimed at atmospheric environment monitoring. The method is based on fusion with lithium metaborate following a preliminary ashing stage of the filters containing the aerosols. The preliminary ashing of samples prevents possible ignition of the filters during fusion and reduces the amount of lithium metaborate required. The samples consisted of 0.45 & micro;m membrane acetate filters loaded with suspended particulate matter from the certified reference material-BIL-1, prepared from filtered model solutions. The BIL-1 reference material is a common reference material in terrigenous matter researches. Ashing process was performed in shielded platinum crucibles in a muffle furnace, with gradual heating increments of 50 degrees C, which ensured the absence of substance losses. After ashing, fusion was carried out in the same crucibles according to a well-established procedure. The described sample preparation ensures complete dissolution of a wide range of determined elements, including both rock-forming and trace elements. Detection limits for rock-forming elements range from 3.7 center dot 10(-1 )to 3.3 center dot 10(3 )& micro;g center dot g(-1), for trace elements from 2 center dot 10(-2 )to 60 & micro;g center dot g(-1), for REE from 1 center dot 10(-3) to 8.4 center dot 10-2 & micro;g center dot g(-1), and depend significantly on the contamination level of the filters. The analytical uncertainty varies from 1.6 to 21 %. The accuracy of ICP-MS determination of 42 elements using the proposed sample preparation method was validated by comparison with certified (recommended) values for the BIL-1 reference material. Deviations of the obtained mean values for most elements in the BIL-1 reference material on filters, particularly for Al, Si, Na, K, Ca, Zr, Hf, Sc, and rare earth elements, do not exceed or are close to 10 %, indicating the applicability of the proposed sample preparation approach for ICP-MS analysis of solids from atmospheric aerosols.
Pincer 1,3-bis((diphenyl)phosphinoxy)phenyl nickel(II) complexes ((POCOPPh)-P-Ph)NiX [X = I, OC(O)CH3, OC(O)CF3] were studied as potential catalysts of electrochemical hydrogen evolution reaction (HER) on a glassy carbon electrode in acetonitrile in the presence of proton donor HBF4 using cyclic voltammetry. It is shown that all the complexes can act as precatalysts for HER. A mechanism for HER involving these complexes is proposed.
The article presents a review of modern functional additives for water- based drilling fluids used to improve drilling efficiency and preserve reservoir properties. The following main groups of additives are considered: nanoparticles capable of improving rheological and filtration properties, reducing friction and fluid losses (up to 40 % when using TiO2); surfactants that improve mud properties by reducing interfacial tension; environmentally safe additives with low toxicity that contribute to sustainable development of the oil and gas industry and reduce production costs. Additionally, natural components of plant origin with biodegradability and promising performance characteristics are considered. Particular attention is paid to polymers acting as swelling and corrosion inhibitors, which allows increasing the resistance of drilling fluids to aggressive conditions. The considered additives allow to optimize the drilling process, reduce the technogenic impact on the environment and increase the working life of the equipment. The article also focuses on the synergetic effects of the combined use of various types of additives, as well as on the potential of their industrial implementation, taking into account modern requirements to environmental friendliness, efficiency and cost- effectiveness. The review reflects current trends in the development of drilling fluids with a focus on stability to thermobaric conditions and environmental safety.
The implementation of the closed-loop ecology concept highlights the need to develop new, highly efficient technologies for processing large-scale inorganic waste. The search for new highly efficient leaching agents is a separate but highly promising area of inorganic synthesis technology, particularly in the organization of valuable component extraction processes. Quartz-leucoxene concentrate is a relatively unclaimed, large-scale product of shale oil production at the Yarega oil and titanium field, yet an economically feasible technology for its comprehensive processing still lacks. As part of this study, the potential use of substandard aqueous TiCl4 solutions obtained during the selective chlorination of quartz-leucoxene concentrate or its byproducts was assessed as a leaching agent in the processing of large-scale mineral waste (raw materials) such as metallurgical scale, brucite-containing refractory waste, and nepheline concentrate to produce innovative complex titanium-containing coagulants was assessed. It was demonstrated that aqueous TiCl4 solutions are superior to aqueous HCl solutions of equivalent concentration in their reactivity with these samples. The extraction rate of iron, magnesium, and aluminum compounds from the corresponding wastes was, on average, 7-12 % higher than with aqueous HCl solutions. Reaction mixtures based on TiCl4 heated up more intensely, and the leaching reaction proceeded, on average, 25 % faster. It has been hypothesized that the increased reactivity of TiCl4 aqueous solutions is due to the wide range of intermediate products of titanium tetrachloride hydrolysis. The data obtained in these experiments will significantly expand the scope of inorganic synthesis, producing a wide range of titanium-containing products (catalysts, sorbents, coagulants, etc.).
The effect of structural characteristics of single-phase hematite samples with the alpha-Fe2O3 structure on the catalytic properties in the methane oxidative conversion (oxidizer O-2) at 750 degrees C was studied. Catalysts with different structural parameters were obtained by calcination of iron (III) oxide at temperatures of 800, 900, 1000, and 1100 degrees C. It is shown that the catalytic characteristics of the alpha-Fe2O3 samples differ significantly. An increase in the calcination temperature of the catalysts in the range of 800-1100 degrees C leads to a significant similar to 30-fold decrease in the specific rate of methane conversion. Calcined catalysts also exhibit different selectivity in the formation of products, CO2, CO and C2H6. Calcination at 800-900 degrees C leads to the formation of deep oxidation catalysts, with a CO2 selectivity of about 93-96 %. The CO selectivity and C2H6 selectivity increase with increasing calcination temperature and amounts of 14 and 55 %, respectively, on a catalyst calcined at 1100 degrees C. The observed catalytic patterns are due to structural changes with an increase in the calcination temperature of alpha- Fe2O3, which are manifested in a decrease in the volume defect of the samples, a decrease in the degree of defect in the crystal lattice of the oxide, in the formation of Fe2+ ions on the surface and in an increase, respectively, the binding energy of the lattice oxygen.
Zinc production solutions are potential sources of gallium. This study examined Ga extraction from solutions with poly(2-ethylhexyl)phosphonitrile acid (P2EHPNA), as well as gallium sorption by various ion exchangers. Ga is extracted very efficiently by P2EHPNA: at an extractant concentration of 0,4 M in kerosene, three extraction stages were sufficient to achieve 97 % Ga recovery, while Zn recovery was only 2 %. Gallium sorption by the following ion exchange resins was also studied: Seplite (R) LSC 750, MM 2026, and Seplite (R) LSC 738. Seplite (R) LSC 750 (a macroporous, chelating resin with an aminophosphonic acid group) is of greatest interest for gallium extraction, demonstrating high Ga- Zn separation factors (beta Ga/Zn = 700-725). Clearly, P2EHPNA and Seplite (R) LSC 750 are of undoubted interest for the separation of gallium from zinc solutions.
The possibility of 33 trace elements determination in silicate rocks after fusion with lithium metaborate was studied on a SUPEC 7000 mass spectrometer (FPI, China) using a collision cell (gas-He) with kinetic energy discrimination (KED) and without cell. For the study, we used reference materials-BHVO-2, BCR-2, G-2, BIL-1, SGD-2A, ST-2A with known contents of the studied elements and natural samples of different compositions, analyzed by a mass spectrometer ELEMENT with a magnetic sector. A procedure has been developed for measuring the concentrations of trace elements in a solution with a complex matrix composition after fusion using external calibration in combination with an internal standard, ensuring the minimization of spectral and non- spectral matrix influence. The determination of analytes from Rb to U was performed without a collision cell, using, where necessary, mathematical correction of the concentrations of some rare earth elements. To determine analytes with the most significant spectral interferences, the efficiency of using a collision cell with KED was assessed and a mode was selected for simultaneously eliminating or reducing spectral interference during measurement. It was found that the use of collision mode with KED (He flow-2.15 ml/min) allowed to reduce the detection limits of analytes, especially Sc, several times, compared to the standard measurement mode on SUPEC 7000. Precision and accuracy for all trace elements are estimated to be 5-10 %. The correctness of the obtained results based on the developed approach is confirmed by comparison with certified concentration values in reference materials.
Samples of hydroxyapatite modified with strontium ions were synthesized. The amount of doped ions during the synthesis varied from 0.1 to 0.5 mol. The phases were identified and their crystallographic parameters were determined using X-ray phase and X-ray structural analysis. It was found that there is an isomorphic substitution of calcium ions by strontium ions in the samples of strontium- modified hydroxyapatite. The surface of the samples was studied using scanning electron microscopy and X-ray spectral microanalysis and an assessment was made of the quantitative distribution of chemical elements on the surface: strontium is uniformly distributed over the surface of the synthesized samples. An assessment of the antibacterial properties in relation to Escherichia coli and Staphylococcus aureus bacteria was carried out. All samples have bactericidal properties.
This paper examines the composition and structure of hydrochars obtained by hydrothermal carbonization (HTC) of aspen wood, as well as porous carbon materials formed during their thermochemical activation at 800 degrees C using KOH, Fe(NO3)(3), and K-3[Fe(CN)(6)]. It was established by chemical and elemental analysis, IR spectroscopy, X-ray diffraction, and scanning electron microscopy methods that increasing the hydrothermal carbonization temperature from 180 degrees C to 240 degrees C leads to the destruction of wood hemicelluloses and cellulose. Hydrochars obtained at temperatures 230 degrees C and 240 degrees C consist of so-called "pseudolignin." Carbon-containing microspheres are formed on the surface of the hydrochars, the number of which increases with HTC temperature. As the hydrochar production temperature increases, their thermal stability is becoming higher. Thermochemical activation of hydrochars at 800 degrees C using KOH, Fe(NO3)(3), and K-3[Fe(CN)(6)] significantly develops the porous structure of the carbon product. The specific surface area of the carbon samples increases in the following order of activators: Fe(NO3)(3) (up to 310 m(2)/g) < K-3[Fe(CN)(6)] (up to 586 m2/g) < KOH (up to 1381 m2/g). Metallic iron compounds and iron carbides Fe3C are uniformly distributed on the surface of the sample activated with Fe(NO3)(3), while iron oxides and iron carbides Fe3C and FeC are present on the surface of the sample activated with K-3[Fe(CN)(6)]. Pseudolignin microspheres forming on the surface of the hydrochars remain on the surface of the activated carbon materials as carbon microspheres. With sizes 1-8 mu m ron-containing samples have magnetic hysteresis and the saturation magnetization value allows them to be isolated from a liquid medium using a magnet.
The reductive catalytic fractionation of agricultural waste-buckwheat husks, sunflower husks, and flax shivesusing a NiRu/C bimetallic catalyst was studied. Based on the following parameters: maximum yield of monomeric phenols (18.6 % based on lignin), individual substance (guaiacyl propanol, 13 % based on lignin), cellulose (27 % based on initial content), and degree of delignification (77 %), flax shives are the most suitable substances among the studied species for current research and industrial applications. Another advantage of flax shives is the high content of guaiacyl propanol in the monophenols obtained (two-thirds). This dominance is due to the isolation and purification of guaiacyl propanol as an individual compound in the process product-a byproduct of the agricultural waste recycling process.
