Hydrolysis of titanium sulphate compounds

The influence of TiOSO4 and free sulphuric acid concentrations in the starting solution on the degree of titanyl sulphate conversion to hydrated titanium dioxide and post-hydrolytic sulphuric acid was studied. Titanyl sulphate solution, an intermediate product in the commercial preparation of titanium dioxide pigments by sulphate route, was used. It was found that the degree of hydrolysis markedly depends on the studied parameters. The lower was the content of TiOSO4 in the starting solution, the higher conversion was achieved. The degree of hydrolysis at the final stage varied between 81 % (420 g TiOSO4 dm−3, 216 g H2SO4 dm−3) and 92 % (300 g TiOSO4 dm−3, 216 g H2SO4 dm−3). The same relation was obtained when changing the concentration of free H2SO4 in the starting solution. The degree of hydrolysis at the final stage varied between 49 % (261 g H2SO4 dm−3, 340 g TiOSO4 dm−3) and 96 % (136 g H2SO4 dm−3, 340 g TiOSO4 dm−3). The particle size of the obtained hydrated titanium dioxide (HTD) also depends on the initial solution composition.