MECHANOCHEMICAL SYNTHESIS OF CALCIUM TITANATE AND RESEARCH OF ITS PHOTOCATALYTIC ACTIVITY

Abstract

Recently much attention is paid to the synthesis and study of the properties of inorganic materials, based on alkaline earth titanates with a perovskite structure that have various polymorphic forms depending on the temperature. Calcium titatanat (CaTiO3) can be selected from the variety of perovskites because of its relatively high dielectric constant, unique photochemical properties, chemical stability, and compatibility with biological tissues, which leads to its application in microelectronics, photocatalysis and biomedicine as bone implants. In this paper, a solid-phase synthesis of calcium titanate was carried out by ceramic technology using mechanochemistry methods. This method allows to obtain calcium titanate directly by mechanochemical activation from the initial mixture of Ca (OH)2 and TiO2, which significantly reduces the energy consumption for its production. Structural changes in the synthesized material during calcination at 120 °C, 200 °C, 400 °C, 600 °C, and 800 °C were studied. The particle size and specific surface area of powders synthesized and calcined at 800 °C was measured by laser diffraction ("Analysette 22") and the low temperature (77K) nitrogen adsorption-desorption vapor, respectively. The phase composition of the obtained materials was studied by X-ray diffraction. It was found on the basis of studies of the particle size distribution that synthesized and calcined powders contain nanoparticles with sizes of 377 and 422 nm. The samples of CaTiO3 calcined at 120 °C and 800 °C have a mesoporous structure, the specific surface area was 46 and 7 m2/g, respectively, and average pore size in powders was 4 nm. It was found by the X-ray diffraction technique that the uncalcined sample contains admixtures of CaCO3 and TiO2 that can be removed completely at 600 °C.The photocatalytic activity of the synthesized material has been studied by the example of Rhodamine B dye decoloration on the calcium titanate calcined at 800°C. It was found that the decomposition degree of dye in solution was 77% for 80 min at a 6.7% shadow adsorption.