Electrochemical oxidation of key pharmaceuticals using a boron doped diamond electrode

This study assesses the degradation by electrochemical oxidation via boron doped diamond (BDD) electrodes of the selected pharmaceutical compounds iopromide (IOP), sulfamethoxazole (SMX), 17-alpha-ethinylestradiol (EE2) and diclofenac (DCF) in simulated wastewater and real hospital effluent wastewater. The influence of the flow rate in the electrochemical cell, applied current, initial compound concentration and wastewater matrix (simulated (SWW) versus real effluent (RWW) wastewater) was evaluated. A kinetic evaluation confirmed that the degradation can be described via pseudo first-order reaction kinetics for all experimental conditions tested. It was shown that SMX, EE2 and DCF degraded readily in SWW and RWW. The degradation of IOP was significantly slower, which is in agreement with previously reported slow degradation kinetics using typical advanced oxidation processes. Activation energies for the degradation reactions were calculated. The flow rate in the electrochemical cell had only a moderate effect on the degradation rate of EE2 and DCF. The applied current, however, had a major effect. The BDD electrochemical oxidation was shown to be an effective technique for removing pharmaceutical components from the effluent of a biological hospital wastewater treatment plant. However, the slower degradation of transformation products should be taken into account, when a full mineralization of the pharmaceuticals is pursued.