Degradation and detoxification mechanisms of organophosphorus flame retardant tris(1,3-dichloro-2-propyl) phosphate (TDCPP) during electrochemical oxidation process

Electrochemical oxidation of aqueous tris(1,3-dichloro-2-propyl) phosphate (TDCPP) by using Ti/SnO2- Sb/La-PbO2 as anode was investigated for the first time, and the degradation mechanisms and toxicity changes of the degradation intermediates were further determined. Results suggested that electrochem-ical degradation of TDCPP followed pseudo-first-order kinetics, and the reaction rate constant ( k ) was 0.0332 min -1 at the applied current density of 10 mA/cm2 and Na2SO4 concentration of 10 mmol/L. There was better TDCPP degradation performance at higher current density. Free hydroxy radical ( & BULL; OH) was proved to play dominant role in TDCPP oxidation via quenching experiment, with a relative contribu-tion rate of 60.1%. A total of five intermediates (M1, C6H11Cl4O4P; M2, C3H7Cl2O4P; M3, C9H16Cl5O5P; M4, C9H14Cl5O6P; M5, C6H10Cl3O6P) were identified, and the intermediates were further degraded prolong-ing with the reaction time. Flow cytometer results suggested that the toxicity of TDCPP and degradation intermediates significantly reduced, and the detoxification efficiency was achieved at 78.1% at 180 min. ECOSAR predictive model was used to assess the relative toxicity of TDCPP and the degradation inter-mediates. The EC50 to green algae was 3.59 mg/L for TDCPP, and the values raised to 84, 574, 54.6, 391, and 8920 mg/L for M1, M2, M3, M4, and M5, respectively, indicating that the degradation intermediates are less toxic or not toxic. Electrochemical advanced oxidation process is a valid technology to degrade TDCPP and pose a good detoxification effect.& COPY; 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.