Enhanced degradation of residual potassium ethyl xanthate in mineral separation wastewater by dielectric barrier discharge plasma and peroxymonosulfate

•DBD was used to activate PMS for synergetic degradation of residual PEX.•Approximately 90.5% of PEX was achieved in the DBD/PMS system.•SO4-, O· H, O2– and 1O2 contributed to PEX degradation especially ·SO4- and O· H.•The addition of PMS increased the dissolved O3 and H2O2 concentration. In the study, dielectric barrier discharge (DBD) plasma was used to activate peroxymonosulfate (PMS) for synergetic degradation of residual potassium ethyl xanthate (PEX) in mineral separation wastewater. The degradation efficiency of PEX in the combined system was obviously higher, indicating that the system had a significant synergistic effect on PEX degradation. After 25 min, approximately 90.5% of PEX and 1.637 of synergetic factors were achieved in the DBD/PMS system at 27.5 kV. The increase of PMS concentration resulted in the balance between the consumption and formation reaction of active species. The degradation efficiency of PEX under acidic conditions was higher. The addition of Cl-, CO32– and HA had an inhibition effect on PEX degradation due to the consumption of ·OH and ·SO4-, and the presence of Cu2+ promoted PEX degradation. The introduction of EtOH had a significant inhibitory effect, indicating that ·SO4- and ·OH played a crucial part. The addition of PMS increased the dissolved O3 and H2O2 concentration in the combined system. The COD degradation and TOC mineralization efficiency gradually improved with the extension of treatment time for actual xanthate wastewater. A possible degradation pathway of PEX was proposed based on the degradation products.