Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
Water Res. 2018 Aug 1;139:66-73. doi: 10.1016/j.watres.2018.03.069. Epub 2018 Mar 31.
Alcohols such as ethanol (EtOH) and tert-butanol (TBA) are frequently used as quenching agents to identify the primary radical species in the persulfate (PS)-based oxidation processes. However, the contribution of alcohol radicals (ARs) to contaminant degradation in this process has rarely been assessed. In this study, trichloroacetic acid (TCA), phenol, and carbon tetrachloride were selected as probes to test the role of ARs in the thermally activated PS system. It was found that the degradation rates of these compounds were largely depended on their reactivities with ARs and the concentration of dissolved oxygen in the reaction system. In the PS/alcohol system, TCA was degraded efficiently under anaerobic conditions, while it was hardly degraded in the presence of oxygen. The results of electron paramagnetic resonance, reducing radical quenching studies, and the analysis of PS consumption suggested that ARs were the dominant reactive species contributing to TCA degradation in the PS/EtOH system under anaerobic conditions. Further studies indicated that ARs could significantly degrade CCl through dechlorination but not phenol. CCl was also degraded efficiently by ARs when oxygen in the reaction solution was completely consumed by ARs. This study highlights the important role of alcohol radicals in the degradation of contaminants during quenching studies in PS-activated processes.
醇类物质，如乙醇（EtOH）和叔丁醇（TBA），常被用作淬灭剂，以确定过硫酸盐（PS）基氧化过程中的主要自由基种类。然而，在这个过程中，醇基自由基（ARs）对污染物降解的贡献很少被评估。在这项研究中，三氯乙酸（TCA）、苯酚和四氯化碳被选为探针，以测试 ARs 在热激活 PS 体系中的作用。结果发现，这些化合物的降解速率在很大程度上取决于它们与 ARs 的反应活性和反应体系中溶解氧的浓度。在 PS/醇体系中，TCA 在厌氧条件下能有效降解，而在有氧存在时几乎不降解。电子顺磁共振、还原自由基猝灭研究的结果以及 PS 消耗的分析表明，在厌氧条件下，ARs 是 PS/EtOH 体系中导致 TCA 降解的主要反应性物质。进一步的研究表明，ARs 可以通过脱氯显著降解 CCl，但不能降解苯酚。当反应溶液中的氧完全被 ARs 消耗时，CCl 也能被 ARs 高效降解。这项研究强调了在 PS 激活过程的淬灭研究中，醇基自由基在污染物降解中的重要作用。
