Heterogeneous photocatalysis of tris(2-chloroethyl) phosphate by UV/TiO2: Degradation products and impacts on bacterial proteome.

The widespread, persistent and toxic organophosphorus esters (OPEs) have become one category of emerging environmental contaminants. Thus, it is in urgent need to develop a cost-effective and safe treatment technology for OPEs control. The current study is a comprehensive attempt to use UV/TiO2 heterogeneous photocatalysis for the degradation of a water dissolved OPEs, tris(2-chloroethyl) phosphate (TCEP). A pseudo-first order degradation reaction with a kobs of 0.3167 min-1 was observed, while hydroxyl radical may be the dominating reactive oxidative species. As the reaction proceeded, TCEP was transformed to a series of hydroxylated and dechlorinated products. The degradation efficiency was significantly affected by pH value, natural organic matters and anions, implying that the complete mineralization of TCEP would be difficult to achieve in actual water treatment process. Based on the proteomics analysis regarding the metabolism reactions, pathways and networks, the significant activation of transmembrane transport and energy generation in Escherichia coli exposed to preliminary degrading products suggested that they can be transported and utilized through cellular metabolism. Furthermore, the descending trend of stress resistance exhibited that the toxicity of products was obviously weakened as the treatment proceeded. In conclusion, hydroxylation and dechlorination of TCEP with incomplete mineralization were likewise effective for its detoxification, indicating that UV/TiO2 will be an alternative treatment method for OPEs control.