PHOTO-CATALYSIS OF PROPANIL UNDER SIMULATED SOLAR LIGHT: FORMATION OF DEGRADATION PRODUCTS AND TOXICITY IMPLICATIONS

摘要

Photocatalytic degradation of propanil in aqueous Au/TiO_2 under simulated solar light was investigated. The decrease of propanil followed first order kinetics with a half life of 55.8 ± 1.7 min in the presence of 50 mg L~(-1) of Au/TiO_2. Eleven degradation products were identified using LC/MS and IC. A degradation pathway was proposed on the basis of the observed transformation products. In addition, LuminoTox bioassays conducted with two different reagents, PECs (photosynthetic enzyme complexes) and SAPS (stabilized aqueous photosynthetic systems), were employed to assess the acute toxicity of solutions treated by photo-catalysis. Overall toxicity of the resulting photo-catalytic by-products was significantly less than that of the untreated propanil. SAPS bioassays proved to be better indicators of toxicity decreases than PECs, and demonstrated a close to 4-fold (3.87) decrease in toxicity following propanil irradiation treatment. This work demonstrated that photo-catalytic degradation using simulated light, coupled with complementary toxicity data, can provide useful information to promote environmental green chemistry approaches for pesticide treatment.