Efficient destruction of emerging contaminants in water by UV/S(IV) process with natural reoxygenation: Effect of pH on reactive species. (15th June 2021)

• Record Type: Journal Article
• Authors: Chu, Yingying; Xu, Lijie; Gan, Lu; Qiao, Weichuan; Han, Jiangang; Mei, Xiang; Guo, He; Li, Wei; Pei, Chun; Gong, Han; Guo, Xuewen
• Is Part Of: Water research. Volume 198(2021)
• Publication Date: 2021-06-15
• Subjects: UV -- Sulfite -- Oxygen -- Advanced oxidation -- Emerging contaminant -- Hydroxyl radical; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2021.117143
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Solution pH played a key role in reactive species transformation in UV/S(IV) More OH can be produced under more alkaline condition with natural reoxygenation The efficiency and mechanism for degrading two emerging contaminants were discussed eaq – and OH contributed to degradation of DEP and BPA respectively at pH 9.2 The use of eaq – shows higher Φ than using OH for the degradation of different ECs. Abstract: UV/sulfite systems with oxygen have recently been considered as advanced oxidation processes in view of the participation of oxysulfur radicals. However, the contribution of OH and the efficiency of destructing emerging contaminants (ECs) in water remain largely unclear. Here, the UV/S(IV) process was applied with natural reoxygenation to degrade two typical ECs, diethyl phthalate (DEP) and bisphenol A (BPA) showing different properties. Solution pH played the key role in determining the reactive species, and both DEP and BPA were more favorably degraded at more alkaline conditions with higher utilization efficiency of SO3 2− . Specifically, the H, O2 −, OH and SO3 − were identified at acidic condition, but the amount of OH accumulated significantly with the elevation of pH. Competitive quenching experiments showed that eaq − and OH dominated the degradation of DEP and BPA at alkaline condition, respectively. Besides, DEP showed higher quantum efficiency for the indirect photolysis and mineralization degree than that of BPA at pH 9.2 mainly due to the direct use of the primary photoproduct. The possible transformation mechanisms of S(IV) and mineralization routes of both pollutants were proposed. This study may provide new insights into the mechanisms involved in UV/S(IV) process and a promising alternative for efficient removal of ECs in water. Graphical abstract: Image, graphical abstract