Mechanism of synthesis of anatase TiO2 pigment from low concentration of titanyl sulfuric–chloric acid solution under hydrothermal hydrolysis.

In order to investigate the influence of Cl−/SO42− molar ratios and hydrolysis temperature on the hydrolysis process and TiO2 pigment, H2TiO3 was prepared with a low concentration of titanyl sulfuric–chloric acid solution by hydrothermal hydrolysis. Under the optimal hydrolysis conditions, 1.5–2.2 μm of H2TiO3 samples were achieved. After doping and calcination, anatase TiO2 pigments demonstrated excellent performance: the achromic ability of tinctorial strength (TCS) and blue phase index (SCX) were 1,429 and 4.07, respectively. As hydrolysis was a significant step in the process, the structure was simplified to a periodic structure of Ti[OH](H2O)3Cl(SO4) to simulate the cluster structures. Based on experimental results and density functional theory (DFT) calculation, the hydrolysis mechanism was presumed to be a process of anionic (OH−, Cl− and SO42−) competition reaction to explain the formation of anatase‐type H2TiO3, and the crystal growth direction of H2TiO3 was also confirmed to be a (OA) and b (OB). [ABSTRACT FROM AUTHOR]