The widespread use of hazardous organophosphate flame retardants (OPFR) has led to the contamination of groundwater and potential drinking water sources. Given the negative impact of OPFR on environmental and human health there is a critical need to identification an effective remediation process. We report herein the ultrasonic degradation of TCEP, a model organophosphate flame retardant, from aqueous solution. GC-NPD was used to monitor the disappearance of TCEP concentration during the ultrasonic irradiation. Our results demonstrate rapid degradation of TCEP upon ultrasonic irradiation at 640 KHz in oxygen-saturated aqueous solution at 7°C temperature. The degradation follows pseudo-first-order kinetics with rate constants varying from 0.09 to 0.02 min<sup>-1 </sup>depending on the initial concentrations over the range of 3.1– 84.1 µM. The rate constant for the degradation decreases with increasing initial TCEP concentration implying the process may be controlled by partitioning at the gas-liquid interface. The degradation follows the Langmuir-Hinshelwood model suggesting also oxidation occurs at the gas-liquid interface. Detailed product studies using ion chromatography show the mono and diester adducts of TCEP (2-chloroethyl dihydrogen phosphate and bis (2-chloroethyl) hydrogen phosphate respectively) are the primary degradation products. Mineralization of TCEP to chloride and phosphate was monitored by ion chromatography over extended irradiation. Mass balances of 47% and 28% were observed for chloride and phosphate anions, respectively after six hours of treatment. Our results suggest that sonolytic oxidation is a rapid and effective method for degradation of TCEP from of aqueous solutions.

Ultrasonic degradation of the flame retardant tris (2-chloroethyl) phosphate (TCEP) in aqueous solution: Kinetics and mechanistic investigation

2019 Spring National Meeting

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