Carbonyl and defect of metal-free biochar trigger electron transfer and 1O2 in peroxymonosulfate activation for carbamazepine degradation

Developing highly anti-interference and nonmetallic peroxymonosulfate (PMS) based advanced oxidation systems is of great importance to remove the persistent contaminants. Herein, the modified biochar (MBC) by Na 2 CO 3 was successfully prepared via ball milling and pyrolysis treatments. Characterization results showed that the MBC had better-developed porosity, richer C=O content, higher defective degree, and lower charge-transfer resistance than the original biochar. The performance of CBZ removal by the MBC was systematically investigated in terms of biochar dosage, PMS concentration, pH, and water matrixes. 0.1   g/L MBC could firstly adsorb 44% of CBZ (2.5   mg/L) within 20   min and then completely remove CBZ within 40   min in the presence 2.0   mM of PMS. A nonradical process of CBZ degradation dominated by 1 O 2 and electron transfer was identified via quenching experiments, electron paramagnetic resonance spectra, and electrochemical characterizations. Consequently, the MBC/PMS system could realize a high CBZ degradation in a wide pH range (3.0−11.0), exhibit strong water matrixes tolerance, and display excellent performance in the real environmental water systems. Furthermore, the removal rate of CBZ could still reach 90% after five reuses. Overall, this study developed an efficient metal-free biochar catalyst that demonstrates exceptional adaptability, stability, and reusability for removing emerging contaminants in environmental remediation applications.