Enhanced removals of micropollutants in binary organic systems by biomass derived porous carbon/peroxymonosulfate

Water pollution usually involves multiple pollutants, and their degradation mechanisms are complicated. In this study, we investigated the degradation of single and binary pollutants (phenol and p-hydroxybenzoic acid (HBA)) in water, using biomass-derived N-doped porous carbon (Y-PC) for peroxymonosulfate (PMS) activation and we found better kinetics and efficiencies of degradation in binary pollutants than single pollutant systems. Electron paramagnetic resonance (EPR), quenching experiments, and electrochemical tests indicated that •OH, SO₄^•-, O₂^•-, and ¹O₂ accounted for the catalytic oxidation of phenol/HBA, while the electron-transfer pathway had an additional contribution to phenol degradation. We unveiled that the HBA degradation rate was similar in the binary and single systems due to the non-selective attack of the micropollutants by •OH, SO₄^•-, O₂^•- and ¹O₂. However, phenol degradation rate was significantly accelerated in the binary phenol/HBA system as compared to that in the single phenol solution, due to the exclusive and selective role of electron transfer pathway. In the binary micropollutant system, a fortified electron-transfer pathway over phenol directly expedited its decomposition and contributed indirectly to this process. This study provides new insights into porous carbon-based advanced oxidation processes for the simultaneous removal of multicomponent contaminants in practical applications.