Testing the role of electrode materials on the electro-Fenton and photoelectro-Fenton degradation of clopyralid

Abstract This work studies the effect of the anode and cathode materials on the degradation of the herbicide clopyralid. Different electrochemical advanced oxidation processes (EAOPs), including electrochemical oxidation with electrogenerated hydrogen peroxide (EO-H2O2), electro-Fenton (EF), and photoelectro-Fenton (PEF) were carried out. The first experiments were focused on the effect of the cathode, where the use of the hydrophobic carbon felt modified by the deposition of carbon black & PTFE mixture (MCF) improves the H2O2 production in comparison to a conventional carbon felt (CF), regardless of the anode material employed. On the other hand, a laser-made Ti/Ru0.3Ti0.7O2 mixed metal oxide (MMO) and a commercial boron-doped diamond (BDD) were compared as anodes. Results obtained point out that the MMO anode promotes the accumulation of this oxidant (H2O2) in bulk. Once characterized by the production of hydrogen peroxide, the second part of this study focused on the degradation of clopyralid with the MCF cathode with different EAOPs. Results demonstrate that clopyralid fastly degrades in the sequence EO-H2O2