Degrading hazardous benzohydroxamic acid in the industrial beneficiation wastewater by dielectric barrier discharge reactor

Abstract

A dielectric barrier discharge (DBD) reactor was developed to efficiently degrade hazardous benzohydroxamic acid (BHA) in industrial beneficiation wastewater. The structural and optimum discharge parameters of the DBD reactor for BHA degradation were determined experimentally. Degradation, visual images, voltage-current waveforms, and Lissajous figures were used to evaluate the BHA abatement performance. After treatment for 40 min, 84.3 % of BHA was degraded. The energy yield attained a maximum of 0.63 mg/kWh at 13.5 kV and a gas flow rate of 30 L/min. Regardless of the energy yield, the maximum degradation of BHA was 98.7 %. The BHA decomposition is described by a first-order kinetic model. The results demonstrate that if the BHA wastewater contains Pb2+ and Cd2+ ions, degradation of BHA is slightly improved by DBD.The degradation mechanism of BHA in the DBD reactor was analyzed by testing the concentration changes of O3, H2O2 in the solution and the influence of •OH, •O2– on the degradation.This confirmed that hydrated electrons were not an important active substance in the degradation when discharge plasma was formed in an air atmosphere. Liquid chromatography-mass spectrometry was used to identify the intermediates of the degradation reaction and predict the degradation pathway of BHA.