Hydrolysis Kinetics of Low-Concentration Industrial TiOSO₄ Solution and Structural Evolution of Metatitanic Acid

Using the industrial low-concentration TiOSO₄ solution as the raw material, the hydrolysis kinetics and structural evolution of metatitanic acid was investigated. The samples were characterized by TiO₂ content, XRD analysis, particle size distribution, FT-IR spectroscopy, Raman analysis, and HRTEM. The curves of hydrolysis yield showed S type shape, and the hydrolysis process consisted of the induction period, rapid hydrolysis period, and mature period. The rapid hydrolysis period was the first-order reaction, and increasing of hydrolysis temperature would shorten the induction period and hydrolysis period while prolonging the mature period had an approximate linear positive correlation on the hydrolysis yield and hydrolysis rate. The actual hydrolysis yield at the graying point was consistent with the calculated hydrolysis yield. The calculated pre-exponential factor k₀ was 1.40 × 10¹⁸ min^-1 and activation energy E_a was of 147.6 kJ/mol. With the hydrolysis temperature increasing, the grain size increased, the lattice stress decreased, the average particle size of metatitanic acid decreased, and the sulfur content decreased, resulting from the growth and adjustment of crystals and colloidal particles. Also, the SO₄^2- ions promoted the formation of anatase TiO₂ crystals. The formation of the precipitated particles underwent processes such as gel, crystal growth, aggregation, and condensation.