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

Abstract

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 up-regulated 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.