The Ultrasound-Assisted Preparation of Crystal Seeds for the Hydrolysis of TiOSO4 to H2TiO3

Abstract

The hydrolysis of an industrial titanyl sulfate (TiOSO4) solution to metatitanic acid (H2TiO3) is the crucial step in the production of titanium dioxide (TiO2) using the sulfuric acid process, and the extra-adding seeded route is generally adopted in industry, in which the quality of the crystal seeds plays a critical role. In this study, the optimal process conditions for preparing the crystal seeds via the NaOH neutralization method were first investigated. Then, the ultrasound-assisted preparation of crystal seeds was studied to explore the effect of the ultrasonic time and intensity on the particle size and particle size distribution of crystal seeds. The results demonstrated that ultrasonic assistance is helpful in obtaining crystal seeds with smaller particle sizes and more uniform particle size distribution, and the quality of the hydrolysis product of H2TiO3, i.e., the particle size and its distribution, is strictly correlated with those of the crystal seeds. Under the optimal process conditions for preparing the hydrolytic seeds, the average particle of the hydrolytic seeds prepared without ultrasonic assistance is 25.50 nm. In contrast, the introduction of ultrasonic assistance in the preservation stage could significantly decrease the particle size and narrow the particle size distribution of the hydrolytic seeds. When the ultrasonic time is 4 min and the ultrasonic intensity is 40 W, the average particle of the hydrolytic seeds is decreased to 23.48 nm. Therefore, the quality of the crystal seeds, as well as that of H2TiO3 products, could be significantly improved by introducing ultrasonic assistance with a suitable intensity at a suitable time in the preparation process of crystal seeds via the NaOH neutralization method.