High-Efficiency Catalytic Ozonation Degradation of Ni Complex Wastewater Using Mn-N Codoped Active Carbon Catalyst

With the rapid development of electroless nickel (Ni) plating industry, a large amount of Ni complex wastewater is inevitably produced, which is a serious threat to the ecological environment. Herein, a novel Mn-N codoped active carbon (Mn-N@AC) catalyst with high catalytic ozonation ability was synthesized by the impregnation precipitation method and was characterized by BET, XRD, Raman, SEM, FTIR, and TPR. Meanwhile, Mn-N@AC showed excellent catalytic ozonation ability, stability, and applicability. When Ni-EDTA (TOC = 400, Ni = 58.05 mg/L) was used as simulated wastewater, the removal efficiency of TOC and total Ni reached 97.8 and 92.7%, respectively, and after three cycles, the TOC removal efficiency was still up to 93.6%. When Ni-EDTA wastewater was replaced with Ni-citrate, Ni-tartaric, and Ni-malate, the TOC removal efficiency remained above 93%. In addition, mechanistic insights by quenching experiments and EPR verified the high removal efficiency of TOC mainly attributed to indirect oxidation of ^·OH and ^·O₂^-, and the potential mechanism was proposed. The work provides insights into the deep removal of Ni complex wastewater by catalytic ozonation with low cost and high efficiency.