Photo-assisted electrochemical abatement of trifluralin using a cathode containing a C₆₀-carbon nanotubes composite

This work reports the potential application of modified gas-diffusion electrode (GDE) with C₆₀-CNT composite, as a stable and efficient cathode material for degradation of trifluralin (TRL) pesticide by photo-assisted electrochemical (PE) process. C₆₀-CNT composite was prepared and characterized. Subsequently, a novel C₆₀-CNT composite modified GDE cathode was developed and the electrochemical and physical characteristics of the modified GDEs were studied. C₆₀-CNT composite/GDE showed great efficiencies for electro-generating H₂O₂, owing to huge surface area and high conductivity. Afterwards, a comparative study of TRL oxidation via photolysis, anodic oxidation (AO) and PE processes using C₆₀-CNT composite/GDE revealed the degradation percentages of 42.2, 48.5 and 93.4%, respectively, after 180 min of treatment. The TRL degradation followed a pseudo-first-order kinetics, being faster in the order: photolysis < AO < PE. The effects of various operational conditions were assessed on the degradation of TRL. From the results, PE process using C₆₀-CNT composite/GDE exhibited great performance for the degradation of TRL (20 mg L^-1) under its original pH, Na₂SO₄ electrolyte concentration of 0.05 mol L^-1, applied current intensity of 300 mA, and flow rate of 12.5 L h^-1. TOC results displayed that 92.8% of TRL was mineralized after 8 h of PE process. In addition, a plausible pathway for mineralization of TRL was proposed according to the identified by-products detected by means of gas chromatography-mass spectroscopy (GC-MS), High-performance liquid chromatography (HPLC) and ion chromatography analyses.