Polyacrylonitrile-derived functional carbon for selective degradation of electron-rich organic contaminants via persulfate activation.

Selective removal of persistent organic pollutants (POPs) from aquatic environments remains challenging in conventional advanced oxidation processes due to the non-selective reactivity of radical species. Direct electron transfer (DET)-mediated persulfate activation is a promising approach for the selective removal of POPs. However, the sustainable synthesis of functionalized catalysts capable of strong persulfate adsorption and efficient interfacial electron transfer remains challenging. In this study, cobalt (Co)-incorporated polyacrylonitrile (PAN) was thermochemically treated under a CO2 atmosphere to synthesize a functional carbon material (CoPANC-CO2). Characterization results revealed that Co and CO2 synergistically enhanced carbon etching, resulting in a mesoporous structure enriched with oxygen-containing functional groups and defect N species. During peroxydisulfate (PDS) activation, CoPANC-CO2 achieved a higher bisphenol A (BPA) removal efficiency (>99%) than its N2-derived counterpart, CoPANC-N2 (49%). Quantitative structure-activity relationship (QSAR) analysis demonstrated the high selectivity of the CoPANC-CO2-mediated DET pathway toward organic pollutant oxidation. In addition, Co incorporation promoted syngas generation (CO + H2 = 27.7 mmol g-1) during the thermochemical treatment of PAN under a CO2 atmosphere. The suppressed accumulation of nitriles and N-heterocyclic compounds in the pyrogenic oil indicated that Co facilitated the secondary conversion of hazardous PAN-derived volatiles into gaseous products. Overall, this work highlights the potential of CO2-assisted thermochemical treatment as a sustainable strategy for catalyst functionalization and the reduction of toxic volatile byproducts.