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

Abstract 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 H 2 O 2 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 H 2 O 2 was electrogenerated in the absence of catalyst. However, in the presence of 0.15 mmol L − 1 FeSO 4 ·7H 2 O (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, CO 2 and H 2 O. It is concluded that wastewater treatments involving H 2 O 2 electrogeneration in a CoPc-modified GDE were effective in removing profenofos and TOC from commercial formulations of profenofos.