Известия Томского политехнического университета: Инжиниринг георесурсов (Jun 2018)
TiO2 particles formation during hydrolysis and thermohydrolysis of TICL4 aqueous-alcoholic solutions
Abstract
The relevance. Titanium dioxide is obtained by flaming synthesis from organooil mediums technology. At the initial stage of that technology during TiCl 4 aqueous-alcoholic solution preparing and dispersion at 100 °C or less TiCl 4 hydrolysis is occurred with intermedi-ate products formation Ti (OH) x Cl y having variable composition. Hereinafter at higher temperatures and smaller residence time in synthesis reactor the intermediate products of hydrolysis are transformed in titanium dioxide. TiO 2 characteristics depend on conditions of TiCl 4 hydrolysis and thermohydrolysis implementation in solution and flame. In this regard determination of possibility of controlling TiO 2 particle sizes at hydrolysis and high temperature synthesis owing to regulating TiCl 4 structure in aqueous-alcoholic mediums is of great scientific and practical interest. The main aim is to study the formation of titanium tetrachloride hydrolysis product particles in aqueous-alcoholic solutions of ethanol, isopropanol and butanol to the sputtering stage at temperature up to 100 °C and titanium dioxide particles in thermohydrolysis at combustion of aqueous-alcoholic solutions at temperature higher than 780 °C. Objects: organo-mineral solutions of titanium tetrachloride and products of their hydrolysis, formed at temperatures up to 100 °C and at combustion of water-alcohol solutions in a flame at temperatures above 780 °C. Methods: dynamic light dispersion for analyzing the sizes of TiCl 4 hydrolysis products in aqueous-alcoholic solution of ethanol, butanol, isopropanol; oscillatory viscometry and the Du-Nuits method for estimating dynamic viscosity and surface tension of the studied solutions; optical microscopy for measuring solution drop sizes; electron microscopy of TiO 2 flaming synthesis products. Results. The study identified that titanium tetrachloride hydrolysis products particles size depends on alcohol nature and particle grow in three stages: initial particle formation - micelles formation - agglomerates. It is experimentally possible to regulate residual chlorine, the shape and size of generated titanium dioxide particles through regulating the precursor composition and temperature at the ther-mohydrolysis stage. The usage of isopropanol and butanol contributes to thermohydrolysis temperature growth and to ultrafine particle formation.
