Dielectric barrier discharge plasma induced degradation of aqueous atrazine
2016
Feng, Jingwei | Jiang, Lin | Zhu, Dan | Su, Kuizu | Zhao, Dayong | Zhang, Jibiao | Zheng, Zheng
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 14 min, atrazine was degradated effectively with a degradation rate of 99 % at the discharge power of 200 W. 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 0.35 min⁻¹ and a G value of 1.27 × 10⁻¹⁰ mol J⁻¹ (98.76 mg kW⁻¹ h⁻¹) at a discharge power of 200 W, respectively. The addition of Fe²⁺ 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 1.52 mg L⁻¹ at a discharge time of 14 min. 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.
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