MgO-based catalyst for degradation of high-concentration organic pollutants with peroxymonosulfate over full pH range and without secondary pollution

Wastewater containing organic dyes is harmful to the ecological environment and human health. This work aimed to develop a strategy to prepare photocatalysts with ultra-high specific surface area for high-concentration pollutant treatment. MgO/KOH-activated N-doped porous carbon (MgO/KNPC) was synthesized using activated porous carbon as a scaffold for nanoconfined MgO. The optimal MgO/KNPC achieved 99.77 % removal efficiency for methylene blue (MEB, 700 mg/L) across the full pH range via peroxymonosulfate (PMS) activation within 30 min. MgO/KNPC also demonstrated versatility in decomposing various antibiotics and dyes, including Rhodamine B (RhB, 450 mg/L), Doxycycline Hydrochloride (DOX, 360 mg/L), Oxytetracycline (OTC, 280 mg/L), and Tetracycline (TC, 250 mg/L), which were nearly completely degraded in natural water within 30 min using MgO/KNPC (20 mg) and PMS (1.0 mmol). Removal efficiency remained above 75 % even after six reused cycles. Radical quenching experiments and electron paramagnetic resonance (EPR) tests confirmed that the coexistence of radical and non-radical pathways in the MgO/KNPC/PMS system. The degradation pathway for MB was proposed by liquid mass spectrometry. This work provides an efficient approach to preparing catalysts with exceptionally high specific surface areas for organic pollutant degradation.