V. Yu. Mayorov

Sol–gel synthesis of porous inorganic materials using “core–shell” latex particles as templates

Here we report on the sol–gel synthesis of porous inorganic materials based on manganese, molybdenum, and tungsten compounds using the “core–shell” siloxane-acrylate latex as a template. The chemical composition and structural characteristics of the materials obtained have been investigated. It was shown that temperature conditions and gaseous media composition during the template destruction controlled the composition and structure of porous materials. To obtain porous inorganic materials for catalytic applications, the “core–shell” latex template was preliminarily functionalized by gold and palladium nanoparticles obtained by thermal reduction of noble metal ions-precursors in a polycarboxylic “shell”. Upon the template removal, noble metals nanoparticles of a size of dozens of nanometers were homogeneously distributed in the material porous structure. The evaluation of the catalytic activity of macroporous manganese, tungsten, and molybdenum oxides under the conditions of liquid phase catalytic oxidation of organic dyes has been performed. The prospects of employing macroporous oxide systems with immobilized nanoparticles of noble metals in the processes of hydrothermal oxidation of radionuclide organic complexes in radioactive waste decontamination have been demonstrated.

Implementation of the continuous-flow hydrothermal technology of the treatment of concentrated liquid radioactive wastesat nuclear power plants

In this work, consideration is given to the feasibility of using hydrothermal oxidation for the destruction of organic 60Co complexes during the course of the treatment of medium-level liquid radioactive wastes with a high salt content—evaporator concentrate in the reactor water cleanup system—formed at nuclear power plants (NPPs). It has been shown that hydrothermal oxidation makes it possible to effectively solve the problem of the selective extraction of the radionuclides of transition metals (60Co, 54Mn) with a minimum volume of solid radioactive wastes being formed. The results of laboratory experiments and pilot tests of the hydrothermal oxidation installation at the Novovoronezhskaya and the Kurskaya NPPs are presented. The general scheme of the hydrothermal technology of processing the evaporator concentrate at nuclear power plants is proposed.

Spark Plasma Sintering as a high-tech approach in a new generation of synthesis of nanostructured functional ceramics

The results of Spark Plasma Sintering (SPS) synthesis of different types of ceramic materials for various industrial applications are presented. A high quality of ceramics is achieved through the originality of the developed approach based on combining SPS technology with other methods of inorganic synthesis, for instance, with sol–gel technology. The suggested approach enables one to synthesize, at the first stage, nanostructured powders of inorganic materials, whose subsequent consolidation by the SPS method ensures the formation of nanostructured ceramics with unique physicochemical characteristics and properties.

Wollastonite ceramics with bimodal porous structures prepared by sol–gel and SPS techniques

In this work, we suggest a novel synthetic route combining sol–gel and SPS for the fabrication of porous ceramics based on wollastonite with bimodal pore size distributions (100–500 nm and 1–500 μm) and high mechanical strength (Youngs modulus from 72.5 to 172 MPa). We studied peculiarities in the formation of the biporous silicate framework using two types of pore forming additives (templates) of various natures, shapes and sizes, introduced during different stages of sol–gel and SPS synthesis: organo-nonorganic (polymer latex of “core–shell” type) and nonorganic (carbonaceous filler). The influence of carbonaceous template content (5% or 25%) on the structural and mechanical properties of ceramics synthesized by spark plasma current was described. The original approach presented here provides formation of wollastonite ceramics with high mechanical strength and a biporous structure that is similar to the texture of bone tissue and is capable of executing its main functions. The obtained ceramics meet all the requirements of the bioceramics class demanded by modern medicine.

Sorption of phosphates on macroporous synthetic calcium silicates

The sorption of phosphate ions on macroporous synthetic calcium silicates has been studied and it has been evaluated whether the latter are suitable to serve as sorbents of geochemical barriers preventing phosphorus losses from agricultural soils.