L. G. Gerasimova

Application of titanium-containing sorbents for treating liquid radioactive waste with the subsequent conservation of radionuclides in Synroc-type titanate ceramics

New nanocrystalline titanium-containing sorbents, namely, layered hydrazinium titanate LHT-9, (N2H5)0.5Ti1.87O4 and synthetic ivanyukite-Na Na2K[Ti4(OH)O3(SiO4)3] · 7H2O, possess high sorption capacity towards cations of different valences and, due to their high chemical stability in acidic and alkaline media, provide the purification of liquid radioactive waste of any composition. The calcination of the product of the radionuclide sorption on LHT-9 and ivanyukite at 1000–1200°C yields mineral-like Synroc-type titanate ceramics applicable for long-term immobilization of sorbed radionuclides with a significant (by 17–250 times) decrease in the amount of radioactive waste.

Preparation of titanium dioxide for heat-resistant sealants

Based on the kinetic data and the mechanism of thermolysis of titanium hydroxide compounds isolated under the thermal or ammonia hydrolysis of titanium(IV) sulfate solution, as well as of ammonium titanyl sulfate (ATS), and by the results of investigating the surface properties of thermolysis products, a method of preparing organophilic titanium dioxide with low bulk density was proposed, which can be used to obtain special silicone-based sealants.

Functional role of amorphous silica in the composite based on titanium phosphate ion exchanger

The influence of the nature of a silicon-containing component used in synthesis of the composite based on titanium phosphate on its composition and sorption properties has been studied using physicochemical methods of analysis. The relationship between the structural modifications of the silicon-containing phase formed in a solution of titanium(IV) sulfate and the sorption properties of the composite ion exchanger thus obtained has been established. It has been shown that the presence of amorphous silica in the composite sorbent favors an increase in its sorption capacity with respect to nickel cations, which is due to the adsorption processes occurring on the surface of the active dopant.

Utilization of waste containing rare-earth elements

The sulfuric acid method of dissolving metallic waste containing rare-earth elements and iron with the obtainment of a sulfate rare-earth concentrate and an iron-containing solution is described. The distribution of the components into solid and liquid reaction products has been studied. The conditions of the conversion of rare-earth sulfate elements into hydroxide and fluoride compounds have been found. The principal possibility of utilizing iron-containing sulfuric acid filtrates with the obtainment of iron oxide pigments of a wide range of colors, catalysts, and coating components of welding electrodes is shown.

Synthesis of the new nano-porous titanosilicates using ammonium oxysulphotitanite

In the last years the interest in new synthetic and natural titanosilicates has increased. Due to the tunable pore diameter and other distinct characteristics, these materials can be utilized for commercially important separations of gas mixtures of similar size molecules, catalysts and removal of radioactive elements from nuclear waste. However, from the point of view of industrial synthesis, scale-up complicated technology and high cost of the agents are limiting factors, hence it is of interest to research new materials to replace expensive pure titanium precursors and stimulate studies to develop an efficient technology. The results of synthesis of the new nanoporous titanosilicates using cost efficient ammonium oxysulphotitanate are presented. By carefully selecting the titanium sources and synthesis parameters, it is possible to obtain titanosilicate Na2K(Ti4(OH)(SiO4)3 analogue of the mineral pharmacosiderite.

Solid-Phase Synthesis in the Technology of Functional Materials Based on Titanium(IV)

A study was made of structural, morphological, and chemical transformations in solid-phase systems based on sulfate, oxide, and hydroxide compounds of titanium(IV) under the intense mechanical activation of solid particles. This enabled one to substantiate the phase formation mechanism initiated by the intense homogenization of the reaction mixture, which is accompanied by a decrease in the particle size, deformation of the particle structure, and the formation of a new active surface. The obtained results formed the physicochemical basis for developing an innovative nonwaste technology for producing a new grade of titanium dioxide in the rutile modification from titanium sulfate salt under a program performed by the Roscosmos State Corporation for Space Activities.

Study of ion-exchange properties of hydrated titanium dioxide towards cesium and strontium cations

Acid-base and sorption properties of spherically granulated material based on hydrated titanium dioxide were studied. It was shown that the sorption capacity of the ion exchanger is due both to the structure (cross-linking density of gels and, consequently, their porosity) and to the number of active acid centers. The kinetic specific features of the sorption of cations were considered and it was found that the sorption kinetics is limited by the intraparticle diffusion. It was shown that the sorbent can be used to purify low-salt technological solutions of liquid radioactive wastes.

The influence of silicic acid on the composition and properties of the material based on composite titanium phosphate

The synthesis of composite titanium phosphate has been performed in one of the incisions of the TiO2-SiO2-H2SO4-H3PO4-H2O system with fixed amounts of H3PO4 and SiO2 with respect to TiO2. The composition of the precursors and the products of their thermolysis was determineded using IR spectroscopy, X-ray phase analysis, TGA analysis, and the BET method. It has been demonstrated that the concentration of titanium (IV) in the initial solution plays a crucial role during the formation of the structure and phase composition of the precipitates. The obtained data may provide a basis on which the directed synthesis of the product with the desired ion-exchange properties could be carried out.

On the behavior of titanium(IV) sulfate in aqueous media used in leather tanning

Physical and physicochemical methods were used to reveal the dependence of the reactivity of Ti(IV) in aqueous media with pH 1–3 on their concentration parameters and holding time. It was demonstrated that aluminum affects the aggregative stability of the titanium systems under study and their stability against hydrolysis. The data obtained made it possible to optimize the composition of solutions and raise the completeness of utilization of their components in the diffusion process of leather tanning.

Obtaining of titanium-containing products via the hydrochloric acid processing of grothite and perovskite

The mechanism and kinetics of phase formation in the thermal hydrolysis of solutions of titanium(IV) oxychloride forming during the hydrochloric acidic processing of grothite and perovskite concentrate is studied. Allowing for the results of physicochemical investigations, the conditions of obtaining functional titanium-containing materials from these solutions are developed. These are the pigment titanium dioxide of the anatase and rutile modifications, titanium dioxide with an increased photochemical activity, and composite titanium silicate material. Their properties are studied and tests are performed, which allows for them to be reasonably recommend for use in the production of varnish-and-paint and building materials, thermally stable catalysts, and for the obtaining of titanium silicate enamels stable with respect to aggressive media.