HSO3-强化Fe3+/S2O82-降解水中双氯芬酸

采用HSO₃^-强化Fe³⁺/S₂O₈^2-降解水中双氯芬酸（DCF），考察了溶液初始pH值，Fe³⁺、HSO₃^-和S₂O₈^2-用量，溶解氧对HSO₃^-/Fe³⁺/S₂O₈^2-体系降解DCF的影响；通过自由基淬灭实验，识别了体系中主要的活性物种；最后，探讨了DCF在该体系中的降解产物和转化路径.结果表明：HSO₃^-可以明显促进Fe³⁺/S₂O₈^2-对DCF的降解，初始pH 4.0时，DCF降解效果最佳.DCF的降解速率随Fe³⁺或S₂O₈^2-浓度的增大而增大；适量增加HSO₃^-浓度可提高DCF的降解，而过量的HSO₃^-对DCF降解有一定抑制作用.在通入氮气条件下，DCF去除率仅下降10.4%，无明显的抑制作用.自由基抑制实验表明，该体系含有SO₄^·-、HO^·和SO₅^·-3种活性自由基，其对DCF降解的贡献率分别为83.0%、12.8%和4.3%.在HSO₃^-/Fe³⁺/S₂O₈^2-降解DCF的反应中共检测出4种产物，据此提出DCF可能的转化路径为：羟基化、脱羧基、脱水和甲酰化反应.

Bisulfite enhanced degradation of diclofenac in Fe3+/persulfate system

The degradation of diclofenac (DCF) by bisulfite enhanced Fe³⁺/persulfate system was investigated. The influence of pH, Fe³⁺ dosage, HSO₃^- dosage, persulfate (PS) dosage and dissolved oxygen on DCF degradation in HSO₃^-/Fe³⁺/S₂O₈^2-system was explored. The main reactive radical species for DCF removal in this system was also identified by scavenging experiments. Finally, The degradation products and transformation mechanism of DCF by HSO₃^-/Fe³⁺/S₂O₈^2- were evaluated. DCF could be effectively degraded by the introduction of HSO₃^- in Fe³⁺/PS process, and the optimal pH was 4.0. The increased initial Fe³⁺, HSO₃^-or PS concentration promoted DCF degradation while excessive HSO₃^- could inhibit its degradation by acting as a SO₄^·- scavenger. The degradation rate of DCF was only reduced by 10.4% with bubbling nitrogen, and there was no obvious inhibitory effect in this system. According to the radical scavenging experiments, the contribution of SO₄^·-, HO^· and SO₅^·- to DCF degradation in HSO₃^-/Fe³⁺/S₂O₈^2- system were calculated to be 83.0%, 12.8% and 4.3%, respectively. Four transformation products were detected using UPLC-Q-TOF-MS. The potential degradation mechanism of DCF was thus proposed showing four reaction pathways including hydroxylation, decarboxylation, dehydration and formylation.