Oxygen-mediated dielectric barrier discharge plasma for enhanced degradation of chlorinated aromatic compounds

Abstract

Chlorinated aromatic compounds (CACs), a kind of refractory pollutants, pose a potential risk to the environment and human health. Herein, dielectric barrier discharge (DBD) plasma is employed to enhance the degradation of 2,4-dichlorophenol (2,4-DCP) from water, and O2 is the most efficient working atmosphere with totally 2,4-DCP degradation in 40 min. O3, ·OH, ·O2– and 1O2 are the main active species responsible for the degradation, while the contribution of hydrated electrons and reactive nitrogen species is almost negligible. Moreover, highly efficient o-Nitrochlorobenzene (o-NCB) and chlorobenzene (CB) degradation and mineralization are also achieved in DBD/O2 process. All the CACs are completely degraded in 60 min following the degradation rate order of CB > 2,4-DCP > o-NCB, which almost follows the order of ionization potential values. The mineralization efficiencies of CB, 2,4-DCP and o-NCB reach 61.14 %, 70.50 % and 92.77 % in DBD/O2 process, respectively, which are 1.74,1.15 and 1.28 times higher than that in DBD process alone. Based on theoretical calculation and intermediates analysis, three common degradation pathways are proposed including hydroxylation, dechlorination and ring-opening. Soil remediation experiments further indicate the high efficiency and promising perspective of DBD/O2 process in CACs contaminated soil treatment. This work is instructive to elucidate the importance of O2 atmosphere in the degradation of CACs by DBD plasma system and provides an alternative way for removing CACs from water and soil.