Complexation between butyl xanthate and Cu enhanced peroxydisulfate activation and cation redox cycle by Fe-Cu-LDH/biochar

Butyl xanthate (BX) is one of the most widely used collector in sulfide flotation. It is harmful to human health but its degradability has not been addressed in depth. In this study, Fe-Cu-Layered double hydroxides/Biochar composites (Fe-Cu-LDH/BC) were prepared and firstly used to activate peroxydisulfate (PDS) for degradation of butyl xanthate. More than 90% of BX could be completely degraded within 10 min under conditions of 20 mg/L BX, 0.2 g/L LDH/BC and 0.1 mM PDS. The high degradation efficiency was owing to the complex formation between catalyst and contaminant molecule by a coordination bond of the Cu in Fe-Cu-LDH/BC and the S in BX. Through DFT calculations, it could be found that this complexation enhanced the adsorption efficiency of LDH/BC on PDS and the reactivity of the Cu site. EPR was applied to analyze the reactive substances in the reaction, and various reactive oxygen species such as O2•−, •OH and SO4•− were detected in the process. In addition, LC-MS was used to analyze and speculate the intermediates and degradation pathways of BX. In conclusion, this material can promote the degradation of BX in water under different conditions and has great potential in treating mine wastewater. Meanwhile, this study proposes new ideas for the synthesis of new catalysts for the efficient degradation of pollutants.