Synergizing electron transfer with singlet oxygen to expedite refractory contaminant mineralization in peroxymonosulfate based heterogeneous oxidation system

This work explored the feasibility of synergizing singlet oxygen (1O2) and electron transfer pathway (ETP) during catalytic decomposition of peroxymonosulfate to advance the refractory pollutant mineralization. N doping strategy was employed to synthesize Mn-C-N catalyst with two independent catalytic sites. The results showed that the contribution of 1O2 and ETP to diclofenac removal could be well matched to 56% and 44% in Mn-C-N/PMS oxidation system, respectively. Mechanism studies revealed that 1O2 would generate intermediate products with low ELUMO, which were rapidly transformed via ETP and finally resulted in improved mineralization performance. Under 0.2 g/L Mn-C-N, 50 mg/L diclofenac, 0.4 g/L peroxymonosulfate, and actual water quality conditions, about 100% removal (15 min) and 70% mineralization efficiency (1 h) was achieved. The above non-radical oxidation system was effective for treating livestock wastewater and secondary effluent. This work prospects the synergy of non-radicals for remediating refractory contaminants-laden wastewater.