Coupled Adsorption and Surface-Bound Radical-Mediated Oxidation on Biomass-Derived Porous Carbon: A Selective Approach for Sulfamethoxazole Removal

Abstract

The development of selective oxidation processes is significant for the efficient removal of organic micropollutants from aqueous streams. Here, we propose a novel catalytic system that involves highly efficient adsorption followed by surface radical-mediated oxidation via conjunction of biomass-derived porous carbon (BPC) and peroxydisulfate (PDS). A series of BPC samples were prepared via pyrolyzing biomass at different temperatures (600 °C, 700 °C, 800 °C). BPC800 had the best reactivity for sulfamethoxazole removal: The maximum adsorption capacity of BPC800 was 529.3 mg/g, which is more than four times that of activated carbon (125.4 mg/g). The co-presence of PDS changed the major removing mechanism from adsorption to degradation. Mechanistic studies using quenching tests, electrochemical characterization, and fluorescence microscopy showed that surface-bound radicals were the dominant reactive species. Efficient performance was also achieved during the treatment of real wastewater and several other micropollutants. The results suggest a novel approach for highly-efficient selective removal of micropollutants from polluted wastewater and offer new insights into the generation of reactive species during the activation of PDS by carbonaceous materials.