Degradation kinetics and disinfection by-products formation of benzophenone-4 during UV/persulfate process

Chen-Yan Hu; Cun Xiong; Yi-Li Lin; Tian-Yang Zhang

doi:10.1080/09593330.2023.2298669

Degradation kinetics and disinfection by-products formation of benzophenone-4 during UV/persulfate process

Environ Technol. 2024 Jan 2:1-12. doi: 10.1080/09593330.2023.2298669. Online ahead of print.

Authors

Chen-Yan Hu^{1

2}, Cun Xiong¹, Yi-Li Lin³, Tian-Yang Zhang⁴

Affiliations

¹ College of Environmental and Chemical Engineering, Shanghai Engineering Research Center of Energy-Saving in Heat Exchange Systems, Shanghai University of Electric Power, Shanghai, People's Republic of China.
² Shanghai Institute of Pollution Control and Ecological Security, Shanghai, People's Republic of China.
³ Department of Safety, Health, and Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan, ROC.
⁴ State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, People's Republic of China.

PMID: 38164528
DOI: 10.1080/09593330.2023.2298669

Abstract

The degradation kinetics, reaction pathways, and disinfection by-products formation of an organic UV filter, benzophenone-4 (BP4) during UV/persulfate oxidation were investigated. BP4 can hardly be degraded by UV alone, but can be effectively decomposed by UV/persulfate following pseudo-first order kinetics. BP4 degradation rate was enhanced with increasing persulfate dosage and decreasing pH from 8 to 5. However, the degradation rate of BP4 at pH 9 was higher than that at pH 8 because of the presence of phenolic group in BP4 structure. and ${SO}_{4}^{-} \cdot$ were confirmed as the major contributors to BP4 decomposition in radical scavenging experiments, and the second-order rate constants between $HO \cdot$ and BP4 as well as those between ${SO}_{4}^{-} \cdot$ and BP4 were estimated by establishing and solving a kinetic model. The presence of $B r^{-}$ and humic acid inhibited the decomposition of BP4, while $N O_{3}^{-}$ promoted it. The mineralisation of BP4 was only 9.1% at the persulfate concentration of 50 μM. Six degradation intermediates were identified for the promulgation of the reaction pathways of BP4 during UV/persulfate oxidation were proposed as a result. In addition, the formation of DBP in the sequential chlorination was evaluated at different persulfate dosages, pH values, and water matrix. The results of this study can provide essential knowledge for the effective control of DBP formation with reducing potential hazard to provide safe drinking water to the public.

Keywords: UV filter; UV/persulfate; degradation kinetics; disinfection by-product (DBP); radical.

Plain language summary

BP4 can be effectively degraded by UV/persulfate process, following pseudo-first order kinetics. $OH \cdot$ and ${SO}_{4}^{-} \cdot$ were identified as the main contributors to BP4 degradation during UV/persulfate process.The degradation pathways of BP4 during UV/persulfate process were proposed.Initial persulfate concentration and solution pH both affected the yield of DBPs.The higher toxic DBPs can be generated in the presence of $B r^{-}$ or $N O_{3}^{-}$ .