Effects of β - Cyclodextrin′ s Derivatives (methyl- β - cyclodextrin and hydropropyl- β - cyclodextrin) on Photodegradation of Parathion- methyl

Photodegradation is one pathway of pesticides degradation in natural environments, and methyl- β - cyclodextrin and hydropropyl - β - cyclodextrin may play a protective role in pesticide decomposition under natural exposure. The photodegradation of parathion- methyl involved with 3 g· L- 1 and 6 g· L- 1 methyl- β - cyclodextrin and hydropropyl- β - cyclodextrin were investigated. The photolytic rates of parathion- methyl increased 4.87～ 6.85 times under the treatment of methyl- β - cyclodextrin or hydropropyl- β - cyclodextrin. The half- life of parathion- methyl decreased from 103.9 h to 18.19 h and 15.16 h, and the photosensitive efficiency is per 84.96 and per 90.29 respectively in the presence of 6 g· L- 1 methyl- β - cyclodextrin and hydropropyl- β - cyclodextrin, indicating the positively photosensitive degradation. The photosensitive efficiency of hydropropyl- β - cyclodextrin to parathion- methyl significantly increased from 0 h to 3 h and 48 h to 60 h, while increased slowly from 3 h to 48h.The positive correlations were observed between photosensitive efficiency of methyl- β - cyclodextrin and hydropropyl- β - cyclodextrin and irradiation time and the treatment concentration of methyl- β - cyclodextrin and hydropropyl- β - cyclodextrin. It was suggested that methyl- β - cyclodextrin and hydropropyl- β - cyclodextrin should have the potential to be widely used in the environmental science in the future.