Photocatalytic degradation of 4-chlorophenol by Au/sol-gel TiO2, Au-Ag/sol-gel TiO2 and immobilized TiO2

Abstract

Photocalytic degradation of 4-Chlorophenol (4-CP) was studied using TiO2, Au/TiO2, Ag/TiO2 and Au-Ag/TiO2 prepared by the sol-gel methods and commercial TiO2 (Degussa P25) as photocatalysts. An amount of intermediate products obtained from the 4-CP degradation was determined. Experiments were carried out in a batch reactor with both catalyst suspended in the solution and coated on glass plates under an 11 W low pressure mercury lamp of 200-280 nm wavelength. Qualitative analysis of solution was obtained by means of a high performance liquid chrom (TOC) analyzer. The results showed that, with TiO2 (sol-gel), a decrease in 4-CP concentration was much faster than that with TiO2 (Degussa P25). In contrast, the reduction rate of TOC with TiO2 (Degussa P25) was much higher than that with TiO2 (sol-gel). The addition of a small amount of either Au or Ag into TiO2 (sol-gel)significantly improved the catalytic acitvity but the addition 0.1% Au into 0.1% Ag/TiO2 did not show any improvement of the catalytic activity. Moreover, the TiO2 suspenson system had a higher initial degradation rate than the TiO2 immobilized system.