Preparation of nanosized anatase TiO2-coated illite composite pigments by Ti(SO4)2 hydrolysis

• The TiO2-coated illite composite pigments were prepared.
• The whiteness reaches 95.73% and oil absorption value reaches 31.35 g/100 g.
• The coating is anatase TiO2 anchored at surfaces by Ti–O–Si bond.
• The TiO2 layers are uniform and dense.

Illite/TiO2 composite pigments were prepared through hydrolysis of titanium sulfate on the surface of illite particles. Some factors that influence the coating process of TiO2 were investigated in single-factor tests, and the whiteness and oil absorption value of coating products were tested. With optimized coating conditions, the whiteness and oil absorption of illite/TiO2 composite pigments can reach to 95.73% and 31.35 g/100 g, respectively. The crystalline phases and surface morphology of the coating products were characterized by X-ray diffraction and scanning electron microscopy. In addition, the precipitated mechanism of anatase was investigated by X-ray photoelectron spectroscopy. The results showed that the microstructure of TiO2 coating on illite substrate was mainly anatase. The uniform and dense TiO2 layers were anchored to the surface of illite by forming Ti–O–Si bond.

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