Comparing the Effects of Types of Electrode on the Removal of Multiple Pharmaceuticals from Water by Electrochemical Methods

Abstract

Considering the lack of information on simultaneously removing multiple pharmaceuticals from water or wastewater by electrochemical methods, this study aimed to investigate the removal of multiple pharmaceuticals by electro-coagulation and electro-oxidation based on two types of electrodes (aluminum and graphite). The synthetic wastewater contained a nonsteroidal anti-inflammatory drug (diclofenac), a sulfonamide antibiotic (sulfamethoxazole) and a β-blocker (atenolol). The pharmaceutical removal with electro-oxidation was much higher than those with the electro-coagulation process, which was obtained from a five-cell graphite electrode system, while the removal of pharmaceuticals with aluminum electrodes was about 20% (20 µM). In the electro-coagulation system, pharmaceutical removal was mainly influenced by the solubility or hydrophilicity of the compound. In the electro-oxidation system, the removal mechanism was influenced by the dissociation status of the compounds, which are attracted to the anode due to electrostatic forces and have a higher mass transformation rate with the electro-oxidation process. Therefore, atenolol, which was undissociated, cannot adequately be eliminated by electro-oxidation, unless the electrode’s surface is large enough to increase the mass diffusion rate.