Natural bentonite clay with a montmorillonite content of 98 %, modified with a solution of sodium metasilicate, has high catalytic activity in the reaction of oxidative degradation of organic azo dyes with hydrogen peroxide by the Fenton-Ruff mechanism in a neutral medium. The activity is due to the presence of iron cations contained in the structure of montmorillonite, as well as protonated silanol and aluminol groups on the surface of the edges of aluminosilicate layers, which are the acid centers of Brensted. The degree of conversion of azo dye from cinema blue with an initial concentration in a solution of 20 mg/l was 99 % in 4 – 6 minutes of contact, at room temperature. The resulting material is well filtered and can be recommended for wastewater treatment from organic substances.

A zinc-containing material based on bentonite clay with a montmorillonite content of 95 wt

The mechanism of adsorption of anionic dyes on montmorillonite modified with sodium metasilicate is investigated. The kinetics of dye adsorption is approximated by a pseudo–second order model, and the adsorption isotherm is analyzed on the basis of the Langmuir and Dubinin–Radushkevich models. The value of average free energy of adsorption E > 8 kJ/mol for all studied dyes, testifying to a surface chemical reaction between dye molecules and protonated silanol and aluminol groups on the surface of the edges of the aluminosilicate layers of the mineral. The adsorption of dyes is directly proportional to the increase in the temperature, mass, and charge of the organic anion and is inversely proportional to the increase in the ionic strength of the solution.

The kinetics of sorption extraction of Al 3+ and La 3+ cations from a solution of phosphoric acid by synthetic macroporous cation exchange resin was studied.In order to obtain the limiting stage of the process, the kinetic data obtained at various temperatures were approximated by pseudo-first, pseudo-second-order models, as well as the Boyd model for various cases of diffusive drag.It was found that the kinetics of adsorption of lanthanum ions is determined primarily by the rate of surface chemical reaction, while the adsorption of aluminum ions is limited by diffusion processes.A probable reason for the selectivity of adsorption may be the formation of complex compounds of different shapes and strengths between metal cations and phosphate anions.

Organo-mineral derivatives of montmorillonite modified by salts of quaternary ammonium compounds are promising adsorbents for wastewater purification from heavy metal anions, as well as anionic dyes and pesticides. The understanding of the mechanism of anion adsorption by the example of montmorillonite modified by didecyldimethylammonium chloride cationic surfactant is expanded. The high rate of chromium anion adsorption, the appearance of adsorption capacity only during charge exchange of the surface, and the pH dependence of adsorption, including for pH-independent nitrate anions, indicate that a significant contribution to adsorption of anions is made by silanol and aluminol groups on the edge surface of the aluminosilicate layers of the mineral. The redistribution of access to various types of adsorption centers of the surface for adsorptive is the mechanism of inversion of the adsorption properties for montmorillonite. The inner negatively charged surface is screened by the double layer of the surfactant molecules that block the interlayer space. The surfactant molecules are not hydrated, which impedes delamination of the mineral in aqueous medium.

The mechanism of montmorillonite modification with sodium metasilicate for inversing its ion-exchange characteristics has been studied. The blockage of the interlayer space in montmorillonite by amorphous silicon–oxygen clusters, which are formed as a result of sodium metasilicate hydrolysis, hinders the access of ions to the internal negatively charged surface of the mineral and increases the strength of bonding between aluminosilicate layers. As a result, adsorption becomes possible only on the outer surface of particles, namely, on active silanol and aluminol groups. This fact has been confirmed by the high rate of the process, as well as by the appearance of the ability to adsorb anions only after the reversal of montmorillonite surface charge. The value of the adsorption of Cr(VI) oxoanions by modified montmorillonite has appeared to be 0.26–1.05 mg/g depending on the synthesis conditions of the samples.

Iron-containing mesoporous silica gel samples were obtained using sol-gel synthesis followed by drying in supercritical carbon dioxide. A relationship between the conditions of preparation and the textural characteristics of the silica gels was established. The materials obtained are considered as promising Fenton catalysts for the oxidation of organic substances in wasted water by hydrogen peroxide.

The conditions of synthesis of cobalt-containing aluminosilicates with a microporous layered columnar structure from montmorillonite clays were correlated with their texture characteristics. The main factors governing the texture properties of the material were shown to be the montmorillonite content in natural clay, the calcination temperature, and the type of hydrolyzing agent and OH − : Me n + ratio during the preparation of the modifying solution.

Установлена взаимосвязь между условиями получения из монтмориллонитовых глин кобальтсодержащих алюмосиликатов со слоисто-столбчатой микропористой структурой и их текстурными характеристиками. Показано, что основными факторами, определяющими текстурные свойства материала, являются содержание монтмориллонита в природной глине, тип гидролизующего агента и соотношение ОН- : Меn+ при получении модифицирующего раствора, температура прокаливания.