Contribution of alcohol radicals to contaminant degradation in quenching studies of persulfate activation process. (1st August 2018)

• Record Type: Journal Article
• Authors: Zhu, Changyin; Zhu, Fengxiao; Dionysiou, Dionysios D.; Zhou, Dongmei; Fang, Guodong; Gao, Juan
• Is Part Of: Water research. Volume 139(2018)
• Page Start: 66
• Page End: 73
• Publication Date: 2018-08-01
• Subjects: Persulfate -- Quenching reaction -- Alcohol radical -- Reductively degradation; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2018.03.069
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: 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 CCl4 through dechlorination but not phenol. CCl4 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. Graphical abstract: Highlights: TCA and CCl4 were degraded efficiently in the persulfate/heat/alcohol system. Alcohol radicals (ARs) were main species accounted for TCA and CCl4 degradation. The role of ARs was testified with free radical quenching and EPR studies.