Mn-modified activated coke activated for Peroxymonosulfate (PMS)-driven advanced oxidation of ammonia nitrogen

Mn-modified activated coke catalysts (AC2) were prepared and employed to activate peroxymonosulfate (PMS) for the removal of ammonia nitrogen from aqueous solution. AC2 was characterized via SEM, XRD, FTIR, and XPS, as well as nitrogen adsorption–desorption. The results revealed that Mn species on the surface of activated coke mainly existed in the form of Mn–O bonds, with the molar ratio of Mn 4+ to Mn 3+ at 1:2. The degradation of ammonia nitrogen followed pseudo-first-order kinetics, and a removal efficiency of 96.74% was achieved under the optimal conditions: pH 7.0, catalyst dosage of 60 mg/L, PMS dosage of 5 mmol/L, and initial ammonia nitrogen concentration of 50 mg/L. The degradation efficiency reached 98.73% in simulated wastewater and 97.47% in real wastewater. Reactive oxygen species (ROS), mainly including SO₄•⁻, •OH, O 2 • − and 1 O 2 , were confirmed as the dominant active species for ammonia nitrogen degradation. The Mn 3+ /Mn 4+ redox cycle in the AC2/PMS system facilitated the generation of these reactive oxygen species.