Using the sol-gel and coprecipitation methods, individual oxides of silicon, titanium, zirconium and double oxides TiO2–SiO2, TiO2–ZrO2, ZrO2–SiO2 have been synthesized. Modification with carboxylic acids was carried out at the final stage of synthesis before drying. Their adsorption and acid-base properties, which allowed establish a number of key parameters that determine the texture and features of the hydrate-hydroxyl structure of the samples, were studied in the range pK = 1.3–11.6. It was shown that the formation of a molecular imprint of aromatic carboxylic acids in composites during their sol-gel synthesis is an efficient approach for creating catalysts for the asymmetric Biginelli reaction.

Ordered mesoporous silicates modified with d-metals were synthesized in situ under low temperature with a sol–gel method at a constant molar ratio of silica and cetylpyridinium template and various pH values and concentrations of metal (oxo)salts. The adsorption properties and the texture of the metallosilicates were studied with a low-temperature nitrogen adsorption–desorption method. We showed that chromo-, zircon-, and vanadosilicates with a low and medium amount of a metal (up to Me/Si ≈ 25/75 mol %) possess the properties of a mesoporous molecular sieve to a greater or lesser extent. The differences in properties of the metallosilicates are due to the incorporation of various heteroatoms into the silica framework and the formation of their off-framework species.

Mesoporous CeO2 and MgO powders and nanocomposites based on them were synthesized by the method of self-propagating high-temperature synthesis, and the mutual influence of magnesium oxide and cerium oxide on the crystal structure, microstructure, and morphology of the obtained materials was studied. It has been established that CeO2 is formed on the surface of magnesium oxide, while the developed surface of the material is preserved. It has been established, that the sizes of CeO2 crystallites in the composition of nanocomposites change insignificantly and range from 6.5 to 7.4 nm, while the values of the specific surface area and average pore diameter of the studied samples depend on the composition and vary in the ranges of 19–41 m2/g and 11.9‒19 nm, respectively. The highest efficiency of photodegradation of dyes of acid telon blue and direct bright blue is observed for samples of MgO–CeO2 (30 mol.%) and MgO–CeO2 (50 mol.%) ‒ 98.5 and 92.5 %, respectively, taking into account the effect of direct photolytic decomposition under the influence of ultraviolet radiation.

The products of oil shale processing are of interest as sorbents for the purification of liquid radioactive waste (LRW). The work studies the adsorption and textural characteristics of samples of heat-treated oil shale by the method of low-temperature adsorption–desorption of nitrogen and sorption of radionuclides from aqueous solutions. It is shown that with an increase in the processing temperature of oil shale, their sorption capacity increases during the extraction of 137Cs and 60Co radionuclides from aqueous solutions, while the processing temperature does not affect the sorption of 85Sr. This effect of the treatment temperature on the oil shale sorption parameters is associated with the removal and carbonization of the organic constituent, as well as the different contribution of ion exchange and adsorption processes to the adsorption of 137Cs, 60Co, and 85Sr radionuclides. Therewith the distribution coefficients of radionuclides reaches 103–104 cm3/g.

A number of acid-modified clays (halloysite, montmorillonite, illite) were studied as catalysts for isoprenol cyclization with isovaleraldehyde to tetrahydropyranols used in perfumery as a mixture of cis- and trans- isomers. The main attention was paid to properties of halloysite nanotubes after treating them with 5% HCl at temperatures from 30 to 100 degrees C. The catalysts were characterized by XRD, EDX, MAS NMR, SEM, and N-2 adsorption-desorption methods. The acid modification of halloysite allows an efficient increase of its acidity and specific surface area, while preserving morphology of nanotubes. On relatively weakly acidic clays, the formation of the target product occurs through a hemiacetal as a precursor. On the contrary, over strongly acidic resin Amberlyst-15, the yield of tetrahydropyranol was significantly lower because of a direct formation of tetrahydropyranols and dehydration by-products. The yield of tetrahydropyranol in the presence of clays was 65-72 %, slightly increasing with an increase in their acidity. The selectivity towards the cis- isomer did not practically depend on the acid sites concentration in clays, decreasing slightly for the trans-isomer with decreasing acidity due to formation of the dehydration by-products. In general, acid-modified clays are promising catalysts for the preparation of tetrahydropyranols under mild conditions and in the absence of any solvent.

Mesoporous titanosilicate structures synthesized by the sol–gel method using the cetylpyridinium template at different Ti/Si ratios are characterized by high specific surface areas A BET ≈ 800 m 2 /g and A ext ≈ 900–1000 m 2 /g, as well as the shape of the isotherms of physical nitrogen adsorption characteristic of the mesoporous molecular sieve MCM-41 with an adsorption branch rising and a section of reversible capillary condensation at a relative pressure of 0.21 < p / p 0 < 0.42. An increase in the Ti/Si ratio and pH values leads to a decrease in the dispersion and surface area of the samples. FTIR spectra confirm the presence of titanium(IV) in the silicate framework. The incorporation of titanium(IV) affects the morphology of titanosilicate samples and reduces the ordering of cylindrical mesopores characteristic of MCM-41.

Sorbents based on manganese oxides were prepared by KMnO4 reduction in aqueous-ethanol medium. The influence of the synthesis conditions (temperature and time of the sol-gel synthesis, type of structure-forming cations, calcination temperature) on the pore structure and on the performance and selectivity in 90Sr sorption was studied. The sorbents have the mesoporous structure with the specific surface area of 180–220 m2 g−1 and mean pore size of 10–20 nm. Manganese oxide of channel structure in the Na+ form, prepared by the reaction at 25°C for 5 h and heat-treated at 350°C, exhibits the highest performance and selectivity in 90Sr sorption (distribution coefficient Kd = 1.04 × 104 cm3 g−1, Sr-Ca separation factor DSr/Ca = 99). The sorbents synthesized exhibit the highest performance and selectivity in neutral and alkaline media.

Композитные материалы, полученные путем импрегнирования активных углей водными растворами хлорида марганца(II), исследованы методами газовой адсорбции, порошковой рентгенографии, атомно-абсорбционной спектрометрии, энергодисперсионной рентгеновской спектроскопии и сканирующей электронной микроскопии. Установлено изменение текстуры и удельных характеристик пористости, микроструктуры и состава полученных композитов в зависимости от кислотной или основной природы поверхности исходных углей, условий пропитки, последующей обработки и температуры прокаливания. Показано, что при импрегнировании “кислотных” углей общий объем пор в 8-11 раз перекрывает объем микропор в отличие от “основных” образцов с их дву- или трехкратным превышением. У “кислотных” углей значения удельной поверхности по БЭТ превосходят аналогичные значения у образцов с основной природой поверхности. Доказано, что полученные композиты содержат марганец в различных оксидных соединениях, представленных рамсделлитом, гаусманитом, манганозитом, биксбиитом и партриджеитом в концентрациях 23-48 масс.%.

Isomerization of alpha-pinene oxide was studied at 20-50 degrees C in the presence of commercial montmorillonites K-10 and K-30, acid-treated illite clay as well as synthetic aluminosilicate AS-36 using cyclohexane as a solvent. The catalysts were characterized by XRD, XRF, FTIR, MAS NMR, thermal analysis and N-2 low-temperature sorption methods The main reaction products at 99.9% conversion of the substrate are campholenic and iso-campholenic aldehydes, the largest amount of which (68.1 wt.%) is formed on illite day treated by 10% HCl. The iso-campholenic/campholenic aldehydes ratio decreases from 0.7 to 0.25 with an increase of acidity of the catalyst from 47 to 153 mu mol/g. The content of products with p-menthane structure (trans-carveol, trans-sorberol, p-cymene, pinol) reaches a maximum (33.0 wt.%) in the presence of medium-acid (104.0 mu mol/g) K-10 clay. The amount of campholenic aldehyde in reaction mixture increases from 34.3 to 48.2 wt.%, and content of iso-campholenic aldehyde decreases from 33.7 to 17.7 wt.% with increasing the drying (calcination) temperature of illite day from 50 to 600 degrees C respectively. The scheme for the formation of reaction products on clays was proposed.

Composite materials resulted from impregnation of active carbons with aqueous solutions of manganese (II) chloride were studied by the methods of gas adsorption, X-ray powder diffraction, atomic absorption spectrometry, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The texture and specific characteristics of porosity, microporosity, and composition of the prepared composites were found to change depending on the acidic or basic nature of the surface of initial carbons, conditions of impregnation, subsequent treatment, and calcination temperature. It was shown that, upon the impregnation of the “acidic” carbons, the total pore volume covered 8–11 times the micropore volume, as distinct from the “basic” samples, which showed only a two- or threefold excess. The specific BET surface determined for the “acidic” carbons exceeded the value found for the samples with a “basic” surface. It was confirmed that the prepared composites contained manganese in various manganese-oxide compounds including ramsdellite, hausmannite, manganosite, bixbyite, and partridgeite at concentrations of 23–48 wt %.

The aim of the research is to study the Fe(III) ion sorption from wines by natural zeolites treated by acid. Acid treatment of clinoptilolite tuff by means of hydrochloric acid solutions was carried out. Equilibrium content of iron(III) was determined by method of atomic absorption spectrometry. The study assumed that the sorption of iron (III) ions by activated natural zeolite occurs generally in accordance with the mechanism of ion exchange. High effect of sorptional cleaning wines after acid treatment of clinoptilolite tuff was found. Optimum parameters of processing acid activation were determined.

Sorption of stable and radioactive strontium ions onto mesoporous manganese oxide of OMS-2 type, prepared by the sol–gel method via reduction of potassium permanganate with polyvinyl alcohol in aqueous medium, was studied. The influence exerted by the pore structure parameters and by the phase and chemical composition of manganese oxide on its sorption properties and selectivity to Sr ions was examined. Manganese oxide samples prepared using a 0.1 wt % KMnO 4 solution exhibit the highest values of the sorption capacity for Sr, about 100–150 mg g –1 , and of the Sr distribution coefficient, K d = (11.5–19.5) × 10 3 cm 3 g –1 . Introduction of 0.1 M NaCl into this solution considerably decreases the sorption of stable Sr ions, and for all the samples the sorption capacity is 25–35 mg g –1 . On the other hand, for the most active sorbents the distribution coefficient in the presence of 0.1 M NaCl increases by a factor of approximately 8–10 relative to distilled water and reaches (91–208) × 10 3 cm 3 g –1 . Introduction of 0.05 M CaCl 2 also decreases the Sr uptake, and the sorption capacity of the most active sorbents for stable Sr ions is 25–35 mg g –1 at K d (85Sr) equal to (0.14–0.35) × 10 3 cm 3 g –1 .

Experimental data on the sol–gel synthesis of manganese oxides formed during the reduction of potassium permanganate by polyvinyl alcohol in an aqueous medium are presented. The physicochemical properties of the obtained manganese oxide systems that depend on the conditions of the synthesis are studied by means of DTA, XRD, SEM, and the low temperature adsorption–desorption of nitrogen. It is found that the obtained samples have a mesoporous structure and predominantly consist of double potassium–manganese oxide K 2 Mn 4 O 8 with a tunnel structure and impurities of oxides such as α-MnO 2 , MnO, α-Mn 2 O 3 , and Mn 5 O 8 . It is shown that the proposed method of synthesis allows us to regulate the size and volume of mesopores and, to a lesser extent, the texture of the obtained oxides, which can be considered promising sorbents for the selective extraction of strontium and cesium ions from multicomponent aqueous solutions.

Change in the dispersity, microstructure, and adsorption properties of mesoporous magnesium hydroxide powders synthesized by the precipitation method from solutions upon introduction of surfactants and under the action of microwave and ultrasonic irradiation was studied. Highly dispersed nanostructured Mg(OH) 2 powders were obtained with average sizes of primary and secondary particles of, respectively, 13–27 and 180–383 nm. The specific surface area, pore volume, and average pore diameter of the samples under study varied, depending on the preparation conditions, within the ranges 86–98 m 2 g –1 , 0.491–0.737 cm 3 g –1 , and 24–32 nm, respectively. It was shown that highly dispersed mesoporous magnesium hydroxide powders can be directionally synthesized by the precipitation method, which opens up wide opportunities for their application as nanoreactors for synthesis of nanosize isolated particles and development of poly-path catalysts on their basis.

Magnesium oxide has found applications as adsorbent, catalyst and ideutifier of the contamination of chemicals and toxic substances in the processes of water and gases purification. In this work, mesoporous magnesium hydroxide and oxide were synthesized from water solutions by easy and cheap wet chemistry method. Crystal structure, particle size distribution and adsorption properties of the synthesized powders were studied. Obtained powders of Mg(OH)2 and MgO showed sufficiently high total pore volume – 0.737 and 1.038 cm3 /g, respectively, which opens an opportunity to use them as nanoreactors for the synthesis of isolated nanosized particles and multidirection catalysts.