Degradation of tris(2-chloroethyl) phosphate (TCEP) in aqueous solution by using pyrite activating persulfate to produce radicals

Abstract Organophosphorus esters (OPEs), as one kind of emerging and toxic contaminant are ubiquitous in various environments. This study investigated the degradation of tris(2-chloroethyl) phosphate (TCEP) as a category OPEs by pyrite (FeS 2 )-activated persulfate (PS). The result shows that near-100% degradation of TCEP was achieved after 120 min in FeS 2 -PS system. The important role of Fe 2+ in the activation mechanism was confirmed by the introduction of Fe 2+ into the PS only system. Radical scavengers experiment and electron paramagnetic resonance (EPR) confirmed the presence of SO 4 ·− and · OH，which revealed that · OH and SO 4 ·− played major roles in TCEP degradation. The effect of various environmental factors, including pyrite and oxidant dosage, inorganic ions and pH were investigated. The result indicated that Fe 3+ and Cl - can accelerate the degradation rate of TCEP and the reaction between TCEP and FeS 2 -PS favors acidic conditions (pH>9). In addition, due to the acidification of pyrite, this system can be applied with a wide pH range. Besides, two oxidation products, C 4 H 9 Cl 2 O 4 P and C 2 H 6 ClO 4 P were identified, which suggest that hydroxylation was probably the main mechanism. This study greatly improves our understanding on TCEP removal in FeS 2 -PS system.