Photodegradation of alachlor with the TiO2 film immobilised on the glass tube in aqueous solution

Alachlor photodegradation was performed using TiO2, which was synthesized by a modified sol–gel method. The thickness of a TiO2 film immobilised by a 5-time dip-coating was 174 nm and the average diameter of TiO2 particles was about 10–15 nm in SEM images. The crystal structure of a TiO2 film calcinated at 300 °C for 1 h was observed as a typical anatase type. The stability of a TiO2 film by a modified sol–gel method was 4% better than TiO2 by a typical sol–gel method. The removal rate of alachlor with both Fe3+ and UV radiation in the absence of TiO2 was 0.28 mg/l/h in 10 h and the removal rate of alachlor with Fe3+/UV in the presence of TiO2 was 0.32 g/l/h, which was higher by 14% than that with Fe3+/UV system. TOC concentration during the alachlor degradation with both TiO2 and UV radiation in the absence of added Fe3+ decreased from 100%, through 81% and 51%, to 44% with time elapses of 4, 8, and 10 h, respectively, while TOC concentration with both added Fe3+ and UV radiation in the absence of TiO2 decreased from 100% to 70% in 10 h.