Application of dielectric barrier discharge plasma for degradation and pathways of dimethoate in aqueous solution

Increasing concerns on environmental water quality have led to the development of effective techniques to remove or decompose water pollutants for health purposes. This paper reported dielectric barrier discharge (DBD) plasma-induced degradation and effects of degradation parameters and degradation pathways of dimethoate in aqueous solution. DBD parameters including discharge power and air-gap distance, dimethoate initial concentration, and radical intervention with radical promoters or scavenger were investigated for their effects on the degradation efficiency by determination of the remaining concentration of dimethoate in the treated solution using HPLC. In addition, identification of intermediates and products were explored using GC-MS, UV-VIS spectrometer and FT-IR techniques. The corresponding DBD plasma degradation pathways of dimethoate were also proposed. The result shows that the degradation efficiency is greater than 96% at the optimum degradation parameters: dimethoate initial concentration = 20 mg L-1, applied power = 85 W, air-gap distance = 5 mm, and treatment time = 7 min. The degradation efficiency is clearly accelerated by adding radical promoters, but sharply decelerated in the presence of radical scavenger. These results have revealed a novel effective method for dimethoate degradation, demonstrated hydroxyl radical (-OH) playing an important role in the degradation pathways, and suggested potential application of DBD plasma for degradation of dimethoate in water. (C) 2013 Elsevier B.V. All rights reserved.