Study of detoxification of methyl parathion by dielectric barrier discharge (DBD) non-thermal plasma at gas-liquid interface：mechanism and bio-toxicity evaluation.

Methyl parathion (MP) as an organophosphorus pesticide has been used in the control of agricultural pests and diseases. Due to its high toxicity and persistence in the environment, MP may pose threat to human health when it is released into environmental water. For MP treatment, people have found that oxidative degradation of MP may generate some intermediates which are more toxic than MP itself, such as methyl paraoxon. Herein, we proposed a new method of applying dielectric barrier discharge (DBD) non-thermal plasma technology to treat MP in aqueous solution, and investigated the influences of different gases, pH value, discharge voltage/power, and main active species on the MP removal efficiency. In particular, the safety of DBD treatment was concerned with analysis of the biological toxicity of the byproducts from the DBD oxidation, and the DBD-induced degradation together with the involved mechanism was explored therein. The results showed that the production of toxic intermediates could be effectively suppressed or avoided under certain treatment conditions. As such, this work demonstrates that the proper application of DBD plasma technology with necessary caution can detoxify methyl parathion effectively, and also provides a practical guide for low-temperature plasma application in treatment of various organophosphorus pesticides in agricultural wastewater.