2007 Volume 56 Issue 2 Pages 99-106
The photocatalytic degradation of crystal violet (CV) was investigated with titanium dioxide particles (ST-01) or titanium dioxide supported on silica gel (hybrid-photocatalyst, HQC51). A CV solution was decolorized by each photocatalyst under UV irradiation. A hypsochromic shift from 590 nm to 562 nm occurred with increasing the UV irradiation time in the presence of a photocatalyst. The shift was probably caused by a stepwise release methyl groups from CV. Some photocatalytic degradation products by ST-01 were identified by using HPLC/MS and MS/MS techniques. It was proved that six methyl groups were stepwisely released from CV under photodegradation, and also dimethylamine was detected as a degradation product. In addition, ammonium ion and nitrate in sample solutions were also determined by flow injection analysis with an indophenol blue method and by using a nitrate ion selective electrode.
