Degradation of potassium alkyl xanthogenate in wet air oxidation: Enhancement method, degradation mechanism and structure impact

Abstract

Wet air oxidation (WAO) is suitable for high concentration organic wastewater treatment, but the oxidation efficiency still needs to be improved and the reaction mechanism is not clear. This work explored the enhancement of different chemicals to the WAO of typical pollutants in metallurgical wastewater and found that persulfate promoted WAO (PWAO) is very efficient in mineralization of potassium ethyl xanthate. The degradation rate and COD removal rate was over 99% and 96% after 30 min reaction, respectively. The oxidation of alkyl xanthate followed the pseudo first-order kinetics, with the constant order of potassium amyl xanthate > potassium ethyl xanthate > potassium butyl xanthate > potassium isopropyl xanthate. The EPR result confirmed that hydroxyl radicals (·OH) was the dominant active species in the WAO and PWAO processes, and persulfate significantly increased the production of ·OH. It was found that the electrophilic reactivity s-(1S) of the S atom in the -CS and the lipophilic coefficient ClgP of xanthate were the main factors affecting the degradation of xanthate, by constructing a quantitative structure–activity relationship model. The results reveal that PWAO can be used in efficient degradation of flotation reagents, based on which a green metal leaching process and simultaneous organics degradation can be possibly developed in future.