Synthesis and photocatalytic properties of highly stable and neutral TiO2/SiO2 hydrosol

Stable, neutral TiO2 hydrosols were prepared using TiCl4 as titanium source, HNO3 as peptizing agent, and SiO2 as stabilizer. Based on XRD, TEM, and FTIR measurements, the TiO2 was rodlike anatase crystallite with a major axis of 15-25 nm and a minor axis of 5 nm. Ti-O-Si bonds were formed, which suppressed the TiO2 grain growth and stabilized the TiO2 hydrosols. The isoelectric points (IEP) of the series hydrosols were 3.1-4.7 pH values and the absolute zeta potentials of the SiO2-modified TiO2 hydrosols were much higher than 50.0 mV under neutral conditions. Methylene blue and reactive brilliant red X-3B were taken as the simulated pollutants to study the adsorption and photocatalytic properties of the obtained hydrosols. The results suggested that the prepared hydrosols had strong adsorption capacity for cationic pollutants rather than anionic ones, and high photodegradation rate of both cationic and anionic pollutants. (C) 2008 Elsevier Ins. All rights reserved