High-efficient degradation of atrazine via UV-driven persulfate process: Transformation patterns, radical chemistry, and residual ecotoxicity evaluation

Atrazine, one of the widely used triazine herbicides, has been proven to endanger both aquatic ecosystems and human health. Herein, the degradation mechanisms of atrazine via ultraviolet-driven persulfate (UV/PDS) and toxicity evolution of its intermediates were specially concentrated. The UV/PDS system demonstrated the exceptional degradation efficacy of atrazine, and the kinetics reaction followed a pseudo first-order kinetic model ( k obs =0.1356 min −1 ). Radical quenching tests and EPR analysis validated that •OH, SO 4 •− , O 2 •- mediated the decomposition of atrazine. The presence of HPO 4 2− and natural organic matter exerted a conspicuous suppression on atrazine removal, whereas Cl − displayed a limited adverse effect. The density functional theory (DFT) and Orbitrap-HRMS manifested that atrazine was destructed through dealkylation, dechloro-hydroxylation and alkyl chain oxidation. Toxicity prediction of these intermediates unmasked that most of them exhibited lower acute toxicity and bioaccumulation effects compared to the pristine atrazine. Effective detoxification of atrazine was confirmed by the observed decline in MDA levels and the recovery of Na +/ K + -ATPase activity and membrane potential in E. coli following UV/PDS treatment. The high-efficient removal of UV/PDS for broad-spectrum antibiotics proved the feasibility for pharmaceutical wastewater. This work afforded novel perspectives on the ecological risks of atrazine intermediates, generating crucial recommendations for the elimination of emerging contaminants through UV-AOPs.