Continuous visible-light photodegradation of emerging pollutants via in-situ cascade Fenton catalysis through dual active sites catalyst

Abstract

The photocatalytic treatment of emerging pollutants has garnered increasing attention by using continuous photodegradation system; however, limitations such as insufficient reactant adsorption and the lack of strong oxidative sites hinder its broader application. In this study, dual active sites functionalized polymeric carbon nitride (PCN) nanorods were synthesized through co-modified with loading of Fe and potassium. The resulting dual-site PCN catalyst exhibited significantly enhanced photocatalytic performance in the degradation of emerging pollutants, including bisphenol A, acetaminophen, carbamazepine, and oxytetracycline, under visible-light irradiation. The introduction of alkali metals as Lewis acid sites efficiently promoted oxygen adsorption and facilitated the generation of reactive H₂O₂. Simultaneously, the incorporation of Fe species enabled cascade catalysis with H₂O₂, forming reactive oxygen radicals via an in situ photo-Fenton system. The degradation pathway of bisphenol A involved C–C bond cleavage, hydroxylation, esterification, and ring-opening processes, while acetaminophen degradation occurred primarily through acetyl-amino group attack. To demonstrate its scalability, a fixed-bed reactor was constructed. It achieved continuous degradation of bisphenol A and acetaminophen with high removal efficiency and stable performance over five days. This long-term continuous photodegradation system, enabled by the dual-functionalized PCN, highlights its significant potential for solar-driven, large-scale wastewater treatment.