Application of Fenton, photo-Fenton and electro-Fenton processes for the methylparaben degradation: A comparative study

Abstract

Endocrine disruptors are often reported in the literature as recalcitrant pollutants in aquatic ecosystems. For this reason, the present study focused on advanced oxidation processes, including Fenton, photo-Fenton, electro-Fenton (EF), and electrochemical oxidation (EO) as an alternative to the degradation of Methylparaben (MeP) from aqueous media. The degradation of MeP by Fenton based processes was completed in 20 min under optimal conditions (16 mg L−1 Fe2+ and 62 mg L−1 H2O2), while for the Photo-Fenton process by a reactor with a 4 W UV lamp, 4 mg L−1 Fe2+ and 52 mg L−1 H2O2, the complete degradation was attained within 16 min. Interestingly, outstanding results were achieved in the Electro-Fenton process carried out in a reactor equipped with a Ti/Ru0,3Ti0,7O2 as a cathode and a platinum anode, which, under optimized conditions (i.e. 4 mg L−1 Fe2+, j = 25 mA cm−2 and 0.05 mol L−1 Na2SO4) only 10 min was required to completely remove the contaminant from both synthetic and tap water. The MeP removal followed pseudo-first-order reaction kinetics in the following order: Electrochemical oxidation (EO) < Fenton < photo-Fenton < electro-Fenton (EF). Finally, after a comparison with the available literature concerning the oxidation of MeP, the EF system here proposed is presented as among the best in removal rate and mineralization as compared with other AOPs, performing better even in real water matrices.