Abstract: To address the challenge of inadequate oxidative degradation of sodium butyl xanthate (SBX) in mineral pro cessing wastewater,this study proposed the use of ultraviolet (UV)-enhanced ozone microbubble (O3 (MB)/UV) system for SBX oxidation,and systematically investigated its degradation performance and mechanism.Reactive oxygen species were iden tified via free radical quenching experiments,intermediates products were analyzed by gas chromatography-mass spectrometry (GC-MS),and reactive sites were predicted based on density functional theory (DFT) calculations,thereby elucidating the degradation pathway.The results showed that the O3 (MB)/UV system exhibited significantly superior SBX degradation effi ciency compared to ozone microbubbles or UV irradiation alone.Under the conditions of ozone dosage of 4 mg/min and UV light intensity of 25 W,the SBX removal efficiency reached over 99.9% within 4 min,with a COD conversion rate of 71%, which was notably higher than that of the H2 O2 /UV (25 W) system (42%).DFT calculations revealed that the highest occu pied molecular orbital (HOMO) of SBX is mainly distributed near the carbonyl (C􀰗O) and thiocarbonyl (C􀰗S) groups, among which the sulfur atom possesses a high Fukui function f- value,serving as the primary reactive site for electrophilic at tack.Mechanistic analysis indicated that the efficient oxidation of SBX relies on the strong oxidizing ability of ozone to initiate thiocarbonyl cleavage and subsequent radical chain reactions,while UV irradiation promotes the generation of hydroxyl radicals (·OH) and superoxide anions (·O 2 ) from ozone,synergistically facilitating the deep mineralization of SBX.This study clar ifies the degradation pathway and mechanism of SBX in the O3 (MB)/UV system,providing a novel,efficient,and secondary pollution-free approach for the treatment of complex mine wastewater.

Key words: ultraviolet light,ozone microbubbles,sodium butyl xanthate,intermediate product,degradation pathway,densityfunctional theory