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Published January 1, 2020 | public
Journal Article

Enhanced photoreductive degradation of perfluorooctanesulfonate by UV irradiation in the presence of ethylenediaminetetraacetic acid

Abstract

Perfluorooctanesulfonate (PFOS) is a persistent organic pollutant (POP) that is globally distributed. Hydrated electrons (e_(aq)–) are known to effectively initiate the decomposition of PFOS. In this study, we explore an alternative photolytic approach employing aquated electrons, e_(aq)– in the presence of ethylenediaminetetraacetic acid (EDTA) in order to enhance the photo-induced degradation of PFOS. EDTA, in this case, serves primarily as a hydroxyl radical scavenger, which inhibits the recombination of e_(aq)– with ∙OH resulting in an increased average photolytic lifetime for e_(aq)–. The net effect is to enhance the degradation of PFOS. UV/EDTA irradiation is shown to increase the overall decomposition percentages of PFOS. The empirical pseudo first-order rate constant for the loss of PFOS is 0.113 h^(-1). In addition, we used laser flash photolysis kinetics to show that the e_(aq)– is the dominant species responsible for the decomposition of PFOS. EDTA also allows for the photolytically-produced hydrated electrons to be used in the presence of air over a wide range of pH. Furthermore, perfluoroalkyl sulfonates with longer chain lengths have higher overall decomposition percentages and increased defluorination percentages. The observed kinetic enhancements appear to be due primarily to the impact of the amine and methylene groups of EDTA with respect of hydroxyl radical scavenging.

Additional Information

© 2019 Published by Elsevier B.V. Received 12 April 2019, Revised 23 July 2019, Accepted 25 July 2019, Available online 26 July 2019. The authors gratefully acknowledge Prof. Weiming Zhang and Dr. Bingdang Wu from State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China, for their kind assistance on the LFP result analysis. This study was supported by the National Natural Science Foundation of China (Project No. 21677109), the Fundamental Research Funds for the Central Universities (Project No. 22120180118, No. 22120180247) and the Major Science and Technology Program for Water Pollution Control and Treatment (Project No. 2018ZX 07109-001-03).

Additional details

Created:
August 22, 2023
Modified:
October 18, 2023