Photocatalysis of Tris-(2-chloroethyl) phosphate by ultraviolet driven peroxymonosulfate oxidation process: Removal performance, energy evaluation and toxicity on bacterial metabolism network

Tris(2-chloroethyl) phosphate (TCEP) as a typical chlorinated-organophosphate esters (OPEs) are identified to be contaminants of emerging concern owing to its health risk and resistance to conventional biological remediation in water matrix. Although ultraviolet-driven radical-based advanced oxidation processes exhibited a well performance in terms of removing refractory emerging organic pollutants, residual biotoxicity and potential environment risks induced by their intermediates products have become a new concern. A comprehensive assessment regarding TCEP elimination using UV-activated peroxymonosulfate (PMS) was performed, which was attempted to provide detailed information about security and fesibility of UV/PMS technology for OPEs control. Degradation of TCEP can be described by a pseudo-first order kinetics equation with a apparent rate constant (0.1311 min-1) and three steady degradation products including C4H9Cl2O4P (m/z 222.969), C2H6ClO4P (m/z 160.976), C6H11Cl2O6P (m/z 280.974) were generated via hydroxylation and dechlorination reactions. The removal efficiency was inhibited in presence of inorganic anions (Cl-, CO32- and H2PO4- ), moreover, the inhibitory effects induced by Cl- was more powerful than the other two. Compared to intact TCEP, metabolic pathways were upregulated expression associated with carbohydrate metabolism, lipid biosynthesis, vitamin metabolism, pyrimidine and purine metabolism, whereas oxidative phosphorylation metabolism, biotin metabolism, oxidation stress response were down-regulated in Escherichia coli exposed to intermediates mixture. The proteomics results confirmed that detoxification of TCEP was achieved in case of an incomplete mineralization, and UV/PMS will be employed as a promising treatment method for controlling micro-pollutants from aquatic environment.