Asymmetric enhancement of persulfate activation by N-doped carbon microelectrode: Electro-adsorption and activation pathway regulation

Abstract

N-doped activated carbon as particle electrode was applied to form a three-dimensional persulfate electro-activation system (ACN/PS/EC) for p-chlorophenol (4CP) removal. The synergy between electro-catalysis (EC) and ACN/PS not only greatly accelerated the PS activation and 4CP degradation processes, but also markedly changed the activation mechanism. Basing on the results of radicals scavenging and electro-adsorption experiments, it is demonstrated that the radical pathway rather than the non-radical pathway was significantly strengthened by using EC owing to the asymmetric electro-adsorption of persulfate ions and 4CP. By quantitative structure-activity relationship analysis, the vital function of graphitic N was unveiled, which exerted action as an active center for PS activation. The effects of operation parameters (including PS concentration, current density, pH, etc.) on the persulfate activation process were also investigated, and the results suggest that the ACN/PS/EC system is a flexible and efficient oxidative system for pollutant degradation, even in complicated wastewaters.