Removal of artificial sweeteners using UV/persulfate: Radical-based degradation kinetic model in wastewater, pathways and toxicity

摘要

Artificial sweeteners (ASS) have been frequently detected in aquatic environment and are of emerging concern due to their environmental persistence, acesulfame (ACE) and sucralose (SUC) are two ASs that are difficult to remove. The ultraviolet/persulfate (UV/PS) advanced oxidation process has been proven to remove ASs in real wastewater effectively. In this study, radical-based degradation kinetic model, pathways and toxicity evaluation of ASs by UV/PS process were explored. ACE and SUC were effectively removed by UV/PS process, and UV photolysis, hydroxyl radicals (HO center dot) and sulfate radicals (SO4 center dot-) contributes the degradation of ASs. A kinetic prediction model for ASs degradation was established based on the second-order rate constants with HO center dot and SO4 center dot-, and the steady state concentrations of HO center dot and SO4 center dot- were calculated through the degradations of two reference compounds. The kinetic model could predict the degradation process of ASs in five real wastewaters effluents. Furthermore, two models based on the kinetic and the water matrices parameters for ASs degradation in wastewater were compared. Finally, the tentative pathways of ASs degradations by UV/PS were proposed. Also, toxicity evaluation showed that ASs after UV/PS treatment enhanced the toxicity on C. carpio liver, and prolongation of treatment time and recovery in fresh water can reduce the toxicity on C. carpio. (C) 2019 Elsevier Ltd. All rights reserved.