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Abstract：
The effective removal of refractory antidepressant in wastewater is challenging. In this study, a novel strategy of cysteine-assisted Fe2+/persulfate system (Fe2+/Cys/PS) was applied for the venlafaxine (Ven, as a typical antidepressant) degradation. The obtained results revealed that the Ven removal was evidently accelerated and enhanced in Fe2+/Cys/PS process, and achieved complete degradation in 5 min with optimal dosage. Further analysis indicated that the Ven degradation efficiency was associated with the chemical concentrations (i.e. Fe2+, Cys and PS) and operational conditions (i.e. pH and temperature). Moreover, the reactions were not impacted by the co-occurring organic matters (i.e. fulvic acid) and inorganic ions (i.e. Cl-) potentially existing in real wastewater matrices. Mechanistic explorations demonstrated that the presence of Cys promoted the Fe3+/Fe2+ redox cycle, and thus enhanced the reactive oxygen species yields (ROS). The OH was considered as the primary ROS in Fe2+/Cys/PS process for Ven degradation via the radical scavenger verification. Also, the main intermediates of Ven degradation were identified, and the possible transformation pathway was proposed, in which the hydroxylation attacked by the OH was the main reaction. Moreover, the active reaction sites in Ven were calculated with the density function theory (DFT), which was consistent with the observed metabolic routes.
摘要：
废水中难降解抗抑郁药的有效去除具有挑战性。在这项研究中,将半胱氨酸辅助的Fe2+/过硫酸盐系统（Fe2+/Cys/PS）的新策略应用于文拉法辛（Ven，作为典型的抗抑郁药）降解。结果表明，Fe2+/Cys/PS过程中Ven的去除明显加速和增强，并在最佳剂量下在5分钟内实现完全降解。进一步分析表明，Ven降解效率与化学浓度（即Fe2+，Cys和PS）和操作条件（即pH和温度）。此外，所述反应不受可能存在于实际废水基质中的共存有机物(即富里酸)和无机离子(即Cl-)的影响。机理探索表明Cys的存在促进了Fe3+/Fe2+的氧化还原循环,从而提高了活性氧的产量（ROS）。通过自由基清除剂验证，OH被认为是Fe2/Cys/PS过程中Ven降解的主要ROS。此外，确定了Ven降解的主要中间体，并提出了可能的转化途径，其中OH攻击的羟基化是主要反应。此外，用密度泛函理论(DFT)计算了Ven中的活性反应位点，这与观察到的代谢途径一致。
