Electro-Fenton degradation of diclofenac: study of the effect of the operating variables on degradation kinetics and the mineralization of the pollutant

A study of the degradation of diclofenac (DCF) in an electrochemical reactor equipped with two carbon cloth (CC) electrodes operating in recirculation mode, is presented. The analysis of the effects of the operating variables on the degradation of the DCF showed that, as expected, the applied voltage has a direct influence on the reactions that take place at the anode and cathode. In fact, the addition of O 2 and Fe(II) to the medium demonstrated that the electro-Fenton (EF) process was taking place and that under the following conditions, 4 V, 0.05 M Na 2 SO 4 , 50 mg/L DCF, 0.25 g Fe(II)-loaded resin, and 50 mL/min, 79.8% of DCF mineralization was obtained in a process described by a pseudo-first order kinetics (k = 0.0184 min −1 ). Using a simulated domestic wastewater effluent, the EF reactor under study not only showed a similar DCF mineralization value (81.8%), but also reasonable energy consumption (2.16 kWh/m 3 ) as well as CC electrode stability upon several treatment cycles. These results suggest that an EF approach using low-cost CC electrodes and neutral pH conditions, constitute a technically and economically viable option for DCF wastewater treatment. Graphical abstract