Synthesis and Characterization of Thorite Nanoparticles by Hydrothermal Method

The synthesis of thorium silicate (thorite) was carried out to characterize the parameters affecting the process. A synthetic thorite with formula ThSiO 4 was prepared by hydrothermal method with a mixture of 0.14 M thorium chloride (ThCl 4 ) solution and sodium silicate containing 0.14 M SiO 2 . The effect of several experimental parameters on synthesis of thorite was investigated. The most important of these parameters were the pH of solution in hydrothermal process and volumetric ratio of SiO 2 : ThCl 4 . The optimum pH in the hydrothermal process was 8–9, which was obtained by buffering with sodium bicarbonate. The increasing of volumetric ratio of SiO 2 : ThCl 4 led to gelatinization of synthetic material. The operating conditions of synthesis of thorite were determined as follows: volumetric ratio of SiO 2 : ThCl 4 = 0.9; pH after adding of 8 M NaOH, 8–8.5; pH after adding 0.5 M sodium bicarbonate, 8–9; temperature of heating in furnace, 250°C; time of heating in furnace, 24 h; pH after hydrothermal process, 8–9; temperature of drying in oven, 60°C; time of drying in oven, 24 h. In each batch of synthesis process, about 2.2 g or 7 mmol of thorium silicate was produced. The purity of thorite was determined 97.80%.