Comparative Investigation of Doping Cobalt in Graphitic Carbon Nitride with Different Precursors for Peracetic Acid Activation: Decontamination Performance, Catalytic Mechanisms, and Practicability

In this study, three different cobalt-doped graphitic carbon nitrides (Co/C3N4) were developed with precursors of urea, dicyandiamide, and melamine to activate peracetic acid. Optimal conditions of pH 4.0 and the cobalt ratio were obtained, with high decontamination performance and low leaching. Characterizations of Co/C3N4 indicate that Co/C3N4 synthesized with different precursors showed similar chemical and crystal structures while exhibiting differences in surface morphology and pore structure. Due to the high specific surface area and pore volume, Co/C3N4 with a precursor of urea showed the best activity, k1, for carbamazepine removal, which was 0.07193 min–1, higher than those with precursors of dicyandiamide (0.05084 min–1) and melamine (0.03499 min–1). The main active species for decontamination was identified by quenching experiments, chemical trapping, electron paramagnetic resonance analysis, and isotope labeling, and the results suggest that high-valent cobalt was the main active species and HO• showed minor efficiency for pollutant degradation. The degradation pathway of carbamazepine was proposed, and the results further confirm the main active species of high-valent cobalt, which mainly reacted with the amino group. Moreover, the practicability of Co/C3N4-activated peracetic acid was evaluated by recycling use, different pollutant treatments, and real wastewater treatment. The results indicate the systems showed better decontamination performance for carbamazepine, sulfamethoxazole, and bisphenol S, could effectively resist the interference of the substrate in real wastewater, and could efficiently remove CBZ within five reuse cycles. This study understood the activity and mechanisms of Co/C3N4-activated peracetic acid with different precursors, which might give new ideas on supporter structure design for Fenton-like catalysis improvement.