Dual nonradical degradation of acetaminophen by peroxymonosulfate activation with highly reusable and efficient N/S co-doped ordered mesoporous carbon

This work demonstrates for the first time the potential application of a novel nonradical oxidation system consisting of N/S co-doped ordered mesoporous carbon (NS-CMK-3) and peroxymonosulfate (PMS). The results showed that the NS-CMK-3 catalyst effectively activated PMS to completely degrade pharmaceutical acetaminophen (ACT). The catalytic performance of NS-CMK-3 was ~20 and 10 times better than that of pristine CMK-3 and single N-doped one (N-CMK-3), respectively. The oxidative system could also remove other pollutants (i.e., sulfathiazole, trans -ferulic acid, orange G, and phenol). A higher content of N (5.3 at.%) and a distribution of graphite-N (28.1%) were determined in NS-CMK-3 than in N-CMK-3. The synergistic effect of N/S co-doping (i.e., graphite-N and thiophene-S) resulted in the enhanced catalytic performance. The activation of PMS by NS-CMK-3 primarily followed two nonradical pathways (i.e., singlet oxygen and catalyst surface-bound reactive PMS complexes), supported by quenching experiments and electron paramagnetic resonance measurements. The p -benzoquinone ( p -BQ) and ACTdimer were main degradation products. The removal of total organic carbon (TOC) was ≈27%, suggesting nonradicals could mineralize ACT. The NS-CMK-3 not only demonstrated superior stability owing to a removal efficiency that was still as high as 98% in the fifth recycle run, but also significantly decreased the potential effects of water constituents (e.g., Cl − , NO 3 − , HCO 3 − , and humic acid) on the removal process. The NS-CMK-3/PMS oxidative system offers a novel strategy to carry out environmental remediation via nonradical processes.