Efficiency and mechanism of electrically activated persulfate-coupled N-doped graphene membrane electrode for removal of PPCPs from wastewater

The development of efficient electrochemical coupling systems for persulfate activation is crucial for expanding the treatment of pollutants such as pharmaceuticals and personal care products (PPCPs) in wastewater. In this study, we present an electrically activated persulfate-coupled N-doped graphene membrane electrode system, which achieves complete (100 %) removal of chlortetracycline hydrochloride (CTC) within 90 min. Nitrogen doping significantly enhances the catalytic activity of graphene membrane electrodes for PMS activation, improving CTC degradation by 45 %. X-ray photoelectron spectroscopy (XPS) identified pyridinic nitrogen and graphitic nitrogen as the dominant PMS-active sites. Free radical quenching experiments and electron spin resonance (ESR) spectroscopy elucidated the reaction mechanism. Under an external electric field, the N-doped graphene membrane electrode functions as an anode, triggering PMS activation and generating reactive oxygen species (ROS), including SO 4 •- , •OH and 1 O 2 . Furthermore, high-performance liquid chromatography-mass spectrometry (HPLC-MS) was employed to analyze intermediate products and assess the toxicity of CTC. The system exhibited excellent pH adaptability and broad applicability for PPCPs removal. This innovative electrochemical coupling system with N-doped graphene membrane electrodes advances the prospects of electrochemical technology in water pollution control. Environmental Implication In this study, we propose an innovative “electrochemically activated persulfate coupled N-doped graphene membrane electrode system” strategy. Using this strategy, we successfully fabricated a graphene membrane electrode material with N-active sites for persulfate activation. The N-sites in this structure enhance the charge distribution, electronic density, and spin density of the graphene material, thereby facilitating the activation of persulfate. The electrode material not only exhibits facile synthesis, excellent activity, and high stability, but also demonstrates considerable promise for applications in the field of environmental remediation.