Degradation of dichloroacetic acid in a novel corona discharge reactor integrated with microbubbles generation

The development of feasible and environmentally friendly technologies to remove dichloroacetic acid (DCAA) from water is needed worldwide to reduce human exposure to this common disinfection byproduct and to minimize cancer risk. In this study, we reported a novel, independently designed water-recirculation-continuous- flow corona discharge reactor (WCD) with integrated microbubble (MB) generation for DCAA treatment. Compared with the performance of WCD or MBs alone, the integrated system (WCD/MBs) showed synergistic effects on DCAA degradation. The functional active species were confirmed to be •OH, •O 2 – , ONOO – , and e - . The effects of the discharge power, bubble size, and carrier gas were evaluated. At a discharge power of 22.9 W and a bubble size of 34.5 μm, the DCAA removal efficiency reached 76% after treatment for 120 min in the air-WCD/MBs reactor. Based on the intermediates detected by IC, GC–MS, and HPLC-QTOF, several DCAA degradation pathways were proposed, including H-abstraction, dechlorination, carbon–carbon bond cleavage, nitrogen dioxide radical reaction, and ipso attack by amine and azido groups. The WCD/MBs system can be applied to tap water, and its energy yield compares favorably with that of other technologies. The novel non-thermal plasma treatment system provides a sustainable and feasible solution for DCAA removal.