Sequestration and Degradation of Waterborne Pollutants in N-Doped Porous Carbon Decorated with Fe Single Sites

Recently, advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) have rapidly developed. However, the low concentrations of waterborne pollutants remain a significant obstacle to their effective removal. This study proposes a "sequestration-degradation" strategy, utilizing a catalyst with high adsorption and catalytic performance to enrich low-concentration waterborne pollutants from water, followed by flushing the packed column with a minimal amount of PMS solution to achieve pollutant degradation and column regeneration. Mesoporous carbon decorated with single-atom iron (FeN4/NC) was prepared and fully characterized. It demonstrated fast adsorption kinetics and a high adsorption capacity for common waterborne pollutants. Additionally, due to its high activity in PMS activation to produce singlet oxygen (1O2) and superoxide (O2•–), FeN4/NC can quickly degrade and partially mineralize 4-chlorophenol (4-CP). We indicate that FeN4/NC is a bifunctional material, with the NC support serving as the adsorption center for 4-CP, while Fe sites serve as activation centers for PMS. A proof-of-concept design for sequestration and degradation of rhodamine B was constructed using FeN4/NC, demonstrating that the current wastewater treatment approach based on the "sequestration-degradation" concept is feasible. Our findings provide a new pathway for improving the efficiency of AOPs in practical applications.