Žurnal neorganičeskoj himii

Natural and synthetic aluminosilicates currently have a wide range of applications. Silicon-containing wastes of rice production are of great interest as a source of raw materials for their production. The purpose of this work is to synthesize micro- and mesoporous materials from rice husk by templat method using PEG-6000. The obtained samples were investigated by differential thermal analysis and IR spectroscopy, which showed the introduction of PEG into the structure of potassium aluminosilicate during sol-gel synthesis. The specific surface area of the samples and pore size distribution were determined by low-temperature nitrogen adsorption, according to which it was found that the pore radius increased from 100 to 200 Å during sol-gel synthesis when the PEG concentration was changed from 5 to 20 mmol/L. The study of the surface of the samples by scanning electron microscopy showed that the introduction of templat changes their surface morphology and promotes structuring.

The purpose of the presented work was to study the possibility of mechanochemical synthesis of polyaluminomodiphenylsiloxanes. For the first time, diphenylsilanediol and tributoxyaluminium were used for synthesis under conditions of mechanical activation. It was found that alumodiphenylsiloxanes with a Si/Al ratio close to the set one are formed, and an increase in the activation time leads to an increase in the rate of homocondensation of the initial diphenylsilanediol and, as a result, an increase in the Si/Al ratio. Using IR- and NMR-spectroscopy, it was found that the aluminum atom forms a polymer aluminosiloxane chain with silanediol, in which butoxyl groups are preserved. It is shown that the obtained compounds have significantly lower thermal stability than spatially branched organometallic siloxanes. The compounds obtained in the work are characterized by modern methods of analysis.

The paper presents the synthesis of layered complex carbide of the composition (Cr,V)C using reactive spark plasma sintering (SPS-RS) and hydrothermal acid etching. Using SEM and TEM, a detailed study of the macro- and nano-structure at each stage of MAXene synthesis was carried out. The presence of characteristic features of the formation of two-dimensional carbide in the form of particles and fragments of a multilayer structure at the macro- and nanolevel was confirmed. Using EDS and XRD, the elemental and phase composition of the samples was studied, as a result it was found that the initial expected MAX-phase Cr₂VAlC₂ in the composition of the sample obtained by SPS is absent. At the same time, a phase of mixed bimetallic carbide (Cr,V)C was detected at all stages of synthesis, for which the crystal lattice parameters, including the unit cell volume, change significantly after acid etching. Obvious changes in the bulk and crystalline structure of (Cr,V)C correspond to the formation of two-dimensional nanoparticles in the synthesized material. The magnetic characteristics study showed that all samples have magnetic hysteresis with relatively low values of coercivity and remanence to saturation magnetization ratio. Low-temperature measurements showed a slight increase in magnetic moment with decreasing temperature for the sample obtained under reaction SPS conditions before acid etching in HF, without significant changes in magnetic behavior of the samples.

Polyferrophenylsiloxanes based on iron(III) chelate and polyphen-ylsiloxane with various ratios of siloxane and sodium hydroxide under mechanochemical activation conditions have been obtained. It is shown that after precipitation with petroleum ether, the yields of polymers are in the range of 37-52%. The polyferrophenylsiloxane composition closest to the given composition was obtained at a Si : Na ratio of 1. The obtained compo-sites were studied by IR spectroscopy, diffractometry, gel chromatography, and thermogravimetry. An XRD study showed the incorporation of iron at-oms into the siloxane structure. The presence of sodium ions during the course of the reaction in subsequent syntheses made it possible to bind the released acetylacetone and obtain polyferrophenylsiloxane with a given Si : Fe ratio. However, with a further increase in the hydroxide content, the Si : Fe ratio was violated. The study of the magnetic properties of polyferro-phenylsiloxanes showed that they are superparamagnets. After heating them to 600°C, the magnetization sharply increases (magnetic saturation) and hysteresis is observed.

The reactions of coordinated ligands in acetylacetonate complexes of chromium and boron difluoride were studied by chromatograph mass spectrometry. It was found that bromo- and thiophenyl-substituted acetylacetonates of boron difluoride, unlike chromium complexes, do not interact with thiophenol. The interaction of thio-substituted chelates with SO₂Cl₂ also occurs differently. For chromium complexes, the reaction is accompanied by the replacement of the thioalkyl or thioaryl substituent by a chlorine atom. Thioethyl-substituted acetylacetonate of boron difluoride reacts with SO₂Cl₂ like aromatic analogues with chlorination of the ethyl group. Thioaryl-substituted acetylacetonate of boron difluoride does not react with SO₂Cl₂. In addition, it was found that bromo- and thiosubstituted chromium acetylacetonates react with sulfenyl chlorides with the replacement of the α-substituent by a chlorine atom. It was suggested that the difference in the reactivity of chromium acetylacetonates and boron difluoride is due to different charge distributions in the chelate cycle. The significant electroacceptor character of the BF₂ group leads to the appearance of a positive charge on the substituent associated with the chelate cycle of the boron complexes.

A new method of creating composite sorption materials based on mixed K-Co and K-Cu ferrocyanides using polyethylene is proposed. The uniqueness of this method lies in the hydrophobisation of the material by integrating polyethylene fibres into the ferrocyanide structure. The surface morphology and structure of the obtained sorbents were investigated by scanning electron microscopy, X-ray phase analysis and low-temperature nitrogen adsorption. The peculiarities of extraction of micro- and macro concentrations of Cs+ cations and 137Cs radionuclide from sea water under static conditions were studied. The approximation of experimental sorption data using the Langmuir and Freundlich equations has been carried out, and the values of limiting sorption Gmax and adsorption equilibrium constant Kl have been calculated. It is demonstrated that the sorbents synthesised with the addition of polyethylene have the best sorption characteristics, achieving up to 99% purification of seawater from caesium ions. The average distribution coefficient of caesium in seawater is 3.8×10^4 ml/g at a solid-to-liquid phase ratio of 1000 ml/g, which indicates the prospects of their application for purification of seawater from radiocaesium.

This work presents the synthesis of a series of sorption materials based on layered Co–Fe, Ni–Fe and Zn–Ti double hydroxides obtained by the most reproducible and environmentally friendly method of homogeneous coprecipitation. This method allows to achieve dispersibility of materials with particle size not more than 10 μm and crystallite size up to 10 nm for Co–Fe and Ni–Fe systems. Application of such a combination of transition metals provides obtaining compounds that have mechanical and chemical stability in aggressive media and actively participate in redox reactions in the liquid phase. The physicochemical and sorption properties of the obtained materials have been investigated with respect to the recovery of uranyl ions U(VI) from aqueous solutions including salt solutions such as Na₂CO₃, Na₂SO₄, KNO₃, NaCl, K₃PO₄ and NaHCO₃ containing competing ions. The recovery rate of uranyl ions from the salt solutions reaches 99% and the Kd distribution coefficients are up to 105 mL/g, indicating high selectivity towards the extracted component. The Co–Fe SDG sample shows the highest value of limiting sorption (Gmax) equal to 101.6 mg/g in seawater and 114.1 mg/g in distilled water. The graphical dependences of residual uranyl ions content after sorption on the total volume of initial solution passed through the column are presented, which show the curve plateauing for Co–Fe and Fe-Ni SDG samples, which is caused by the ultimate saturation of the material with the extracted component. It was determined that the indices of the total dynamic sorption capacity for the studied sorption materials based on SDG can reach 101.4 mg/g for the SDG Co–Fe sample, but for the SDG Zn–Ti sample this index is much lower than 40.2 mg/g. The presented studies allow us to conclude that the obtained materials based on layered double hydroxides Co–Fe, Ni–Fe and Zn–Ti have a significant potential for sorption extraction of uranyl U(VI) from aqueous media of medium salinity.

In this study, we present a novel surface modification approach for magnetic composite materials based on Fe₃O₄/Zn-Al layered double hydroxides (LDH) to enhance their hydrophobic properties. We have systematically investigated the interaction mechanisms between various surfactants (stearate, oleate, and sodium dodecyl sulfate) and the Fe₃O₄/Zn-Al-LDH surface. Our research examined how ethanol-mediated hydrophobization affects the material's porous and crystalline structure. We developed innovative synthesis routes for both granulated and sponge-like magnetic sorbents utilizing melamine-formaldehyde resin as a binding matrix. Under optimized conditions, the resulting Fe₃O₄-LDH-ST granulated sorbents and MEL-Fe₃O₄/LDH-ST sponge-like materials demonstrated exceptional oil sorption capacities of 0.60 and 21.36 g/g, respectively, combined with significant magnetic susceptibility, enhanced hydrophobicity, and excellent regeneration potential. These engineered materials show promise for marine oil spill remediation and environmental monitoring applications.

Paint coatings with optimal performance properties are an important element in the safety and efficiency of marine and river vessels, as well as other objects exploited in the aquatic environment. In this work for modification of paint and varnish coatings we used a material based on calcium hydrosilicate, obtained by hydrothermal method from technogenic waste in the form of borogypsum. The synthesis product with specific surface 155.2 m²/g and density 3.1 g/cm3 is characterized by the presence of phases of calcium sulfate, tobermorite and xonotlite and consists of mainly from needle particles. The influence of calcium hydrosilicate, partially replacing calcium carbonate, on the properties of paint coatings based on acrylic copolymer has been studied. Physical and mechanical properties, antifouling effect, water absorption and erosion rate of paint coatings were studied.The results of the study showed the efficiency of calcium silicate use to improve the physical and mechanical properties of coatings: an increase in strength by 1.5 times was found. At the same time, the addition of calcium hydrosilicate at partial replacement of calcium carbonate does not decrease the antifouling effect.