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 O, 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.