Effect of cathode material on electro-Fenton process efficiency for electrocatalytic mineralization of the antibiotic sulfamethazine

Cathode material plays a crucial role in electro-Fenton process since its efficiency depends to the ability of the cathode material to generate H2O2 which controls the production rate of hydroxyl radicals, the main oxidizing agent for destruction of organic pollutants. Therefore, this study focused on the role of different cathode materials (i.e., carbon sponge (CS) of five different porosities, carbon felt (CF), and stainless steel (SS)) on the electrochemical oxidation and mineralization of sulfamethazine (SMT) in aqueous solution. Prior to studying the degradation and mineralization power of the cathodes under examination, we performed a systematic study of the production of H2O2. It was found that all the carbon sponge cathodes give high amounts of H2O2 in the solution, the most effective being the 45 ppi (pore per linear inch) porosity followed by carbon felt cathode. Stainless steel only gives poor amounts of H2O2 for current of 50 and 100 mA. The degradation and mineralization experiments were consistent with the yield of H2O2 for all electrolytic systems; electrolytic cells with higher H2O2 production capacity showed better performance on SMT degradation/mineralization. The most effective electrolytic system for SMT removal from polluted water was Pt/CS 45 ppi reaching a mineralization rate of 91.1% at 300 mA while the less effective was Pt/SS with only 41% mineralization.