High-efficiency treatment of electroless nickel plating effluent using core-shell MnFeO-C@AlO combined with ozonation: Performance and mechanism.

Heterogeneous catalytic ozonation (HCO) has been widely applied for the treatment of wastewater. In order to maintain the structural stability and surface catalytic activity of heterogeneous catalysts during the HCO treatment of electroless nickel plating effluent (ENPE), a MnFeO-C@AlO catalyst with a core-shell structure was synthesized. MnFeO-C@AlO was characterized and applied in the removal of total nickel (T) and organic contaminants from actual ENPE, using a coupled system of HCO combined with a magnetic dithiocarbamate chelating resin (MnFeO-C@AlO/O-MDCR). Results show that embedding AlO with C and MnFeO significantly increased the T removal efficiency (99.3%), enhanced the O-utilization efficiency and improved the generation of reactive oxygen species (ROS). The reaction rate (k = 0.7641 min) and O-utilization efficiency established for T removal (ΔT/ΔO =0.221) by the MnFeO-C@AlO/O-MDCR system, were 220% and 140% higher than the AlO/O-MDCR system, respectively. Catalytic mechanism analysis demonstrated that surface hydroxyl groups, oxygen vacancy, metals, the carbon surface and its functional groups, can all potentially serve as catalytic active sites, with O and •OH considered to the predominant ROS. Overall, these findings verify that the synthesized MnFeO-C@AlO catalyst possesses excellent catalytic capabilities and outstanding structural stability, making it suitable for practical application in the treatment of wastewater effluent.