Hybrid Composites Based on Silica and Titanium(IV) Phosphate for Sorbents

Abstract

Using a titania–silica precursor with the composition SiO2 ∙ TiO2 ∙ хH2O, isolated via hydrochloric acid treatment of a process waste from the dressing of apatite–nepheline ore, we have prepared a hybrid composite containing silica as a matrix for an α-Ti(HPO4)2 ∙ H2O functional filler (STP). The key step of the synthesis process is a solution-phase reaction of the precursor with phosphoric acid. Our results demonstrate that a preferable sequence of steps begins with the mechanical activation of the components of the precursor, with their phase transformations. Using a combination of subsequent heat treatment with phosphoric acid with different concentrations under atmospheric conditions and in an autoclave, we have found conditions for chemical reactions that change the composition and structure of the final product and, accordingly, its sorption activity for cesium and strontium cations. The synthesized hybrid inorganic material can be effectively used to remove radionuclides and heavy nonferrous metal cations from liquid discharges. The proposed technology significantly surpasses known processes in economic and environmental characteristics.