Effect of Fe2 + on the degradation of the pesticide profenofos by electrogenerated H2O2

The purpose of the study was to evaluate the degradation of the organophosphate pesticide profenofos in acidic medium using a gas diffusion electrode (GDE) modified with 5.0% cobalt phthalocyanine (CoPc). The degradation of profenofos was based on oxidation by H2O2 electrogenerated in situ, and experiments were performed in the absence or presence of Fe(II) catalyst. Removal of the pesticide by anodic oxidation was minimal (~ 20%), and reached only 36% when H2O2 was electrogenerated in the absence of catalyst. However, in the presence of 0.15 mmol L− 1 FeSO4·7H2O (electro-Fenton reaction), profenofos removal attained 91% after 60 min of process time while total organic carbon (TOC) was reduced by 37%. Prolonged electrolysis under similar electro-Fenton conditions showed that 100% profenofos removal could be achieved after 2 h and a 89.9% reduction in TOC could be attained after 4 h. Analysis by gas chromatography-mass spectrometry of the by-products formed during the process revealed the progressive degradation of profenofos to o- and p-benzoquinone, with subsequent rupture of the aromatic ring to form oxalic acid and, ultimately, CO2 and H2O. It is concluded that wastewater treatments involving H2O2 electrogeneration in a CoPc-modified GDE were effective in removing profenofos and TOC from commercial formulations of profenofos.