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

Stable, neutral TiO(2) hydrosols were prepared using TiCl(4) as titanium source, HNO(3) as peptizing agent, and SiO(2) as stabilizer. Based on XRD, TEM, and FTIR measurements, the TiO(2) was rodlike anatase crystallite with a major axis of 15-25 nm and a minor axis of 5 nm. TiOSi bonds were formed, which suppressed the TiO(2) grain growth and stabilized the TiO(2) hydrosols. The isoelectric points (IEP) of the series hydrosols were 3.1-4.7 pH values and the absolute zeta potentials of the SiO(2)-modified TiO(2) 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.