1. 296 to 1.357 g/cm3 is obtained. The reaction solution is subjected to pressure filtration through a plate frame to obtain a cake-like lithopone powder having a water content of not more than 45%. The mixture is calcined in a dry roaster to change the crystal form of the lithopone, and then acid-washed with sulfuric acid at a temperature of 80 °C. Finally, it is washed with water, reinforced with coloring agent, pressure filtration, drying and milling.
Sulphate process. The ilmenite is reacted with sulphuric acid giving titanium sulphate and ferric oxide. After separation of ferric oxide, addition of alkali allows precipitation of hydrous titanium dioxide. The washed precipitate is calcined in a rotary kiln to render titanium dioxide. The nucleation and calcination conditions determine the crystalline structure of titanium dioxide (e.g. rutile or anatase).
Titanium dioxide (TiO2) is a multifunctional semiconductor that exists in three crystalline forms: anatase, rutile, and brookite. Owing to an appropriate combination of physical and chemical properties, environmental compatibility, and low production cost, polycrystalline TiO2 has found a large variety of applications and is considered to be a promising material for future technologies. One of the most distinctive physical properties of this material is its high photocatalytic activity (Nam et al., 2019); however, more recently it has attracted growing interest because of its resistive switching abilities (Yang et al., 2008).