Metal-Free Carbon with Synergistic Enrichment Catalysis for Rapid Removal of Antibiotics

Abstract A freeze-drying-assisted pyrolysis strategy was used to prepare nitrogen-doped porous carbon (FNC800) from glucose and dicyandiamide (600–900 °C). FNC800 possessed hierarchical porosity (specific surface area 747.36 m2 g–1) and pyridinic-N sites. After 30 min adsorption–desorption equilibration, FNC800 removed 76.83% of tetracycline hydrochloride (TCH). Subsequent addition of peroxymonosulfate (PMS) produced near-complete attenuation of dissolved TCH within 1 min (apparent rate constant k = 3.49 min–1) with 57.74% total organic carbon (TOC) removal. Radical quenching, electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements indicated a predominantly nonradical pathway in which singlet oxygen (1O2) was the principal oxidant, with secondary contributions from superoxide (O2•–) and interfacial electron transfer. High TCH removal was maintained at pH 1–11 and declined to ∼30% at pH 14; common inorganic anions caused limited inhibition, whereas humic acid reduced adsorption. Removal decreased from 100 to 90.4% over five cycles. These results show that metal-free porous carbon can couple pollutant enrichment with rapid PMS activation for antibiotic remediation.