Dielectric barrier discharge plasma induced degradation of aqueous atrazine.

Abstract

Degradation of herbicide atrazine in aqueous solution was investigated using a plate type dielectric barrier discharge (DBD) plasma reactor. DBD plasma was generated at the gas-liquid interface of the formed water film. At discharge time of 14min, atrazine was degradated effectively with a degradation rate of 99% at the discharge power of 200W. The experimental data fitted well with first-order kinetics and the energy efficiency for 90% degradation of atrazine (G value) was calculated, obtaining a rate constant of 0.35min(-1) and a G value of 1.27 × 10(-10)molJ(-1) (98.76mgkW(-1)h(-1)) at a discharge power of 200W, respectively. The addition of Fe(2+) increased the rate constant and G value dramatically, and a significant decrease of the rate constant and G value was observed with the addition of radical scavengers (tert-butyl alcohol, isopropyl alcohol, or Na2CO3). The generated aqueous O3 and H2O2 were determined, which promoted the degradation of herbicide atrazine. Dechlorination was observed and the experimentally detected Cl(-) was 1.52mgL(-1) at a discharge time of 14min. The degradation intermediates of atrazine were detected by means of liquid chromatography-mass spectrometry; dechlorination, hydroxylation, dealkylation, and alkyl oxidation processes were involved in the degradation pathways of atrazine.