Mechanistic Insights into Efficient Peroxymonosulfate Activation by Waste-Derived Porous Carbon: Dominant Nonradical...

This study fabricated KOH-activated coal-pit-derived porous carbon (PC) to activate peroxymonosulfate (PMS) for degrading the model organic pollutant Orange G (OG), systematically clarifying the effects of operational variables and reaction mechanisms. Superior catalytic performance was attained with PC, achieving 91.8% OG removal via PMS activation. This performance was ascribed to its well-developed porous structure and abundant active sites. Kinetic analysis revealed that the PC/PMS system had a first-order rate constant (k_obs) of 0.0607 min^-1, 40-fold higher than PMS alone, confirming the synergistic catalytic effects. Optimal operational conditions were 1.0 mM PMS, 0.100 g/L PC, and an acidic pH (3.0). Anions NO₃^- and HCO₃^- inhibited degradation via radical quenching, whereas Cl^- promoted OG removal through active chlorine species formation. PC maintained stable adsorption (≈22%) across pH 2-9, with acidic conditions favoring SO₄•^-/•OH generation and alkaline conditions reducing •OH efficiency. Quenching experiments and electron paramagnetic resonance (EPR) identified nonradical ¹O₂ as the dominant oxidant (83.18% contribution). Structural analysis confirmed C═O, C═C groups, and structural defects as primary active sites, which facilitated PMS activation via electron-withdrawing effects and surface redox reactions. Although PC recyclability decreased from 89.02 to 64.78% over three cycles due to pore blockage, the system exhibited broad applicability to sulfonic acid-containing dyes. This work highlighted that porous morphology and surface chemistry were critical for PC-mediated PMS activation in pollutant remediation, offering guidance for optimizing industrial wastewater treatment.