High-efficiency treatment of electroless nickel plating effluent using core-shell MnFe₂O₄-C@Al₂O₃ combined with...

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 MnFe₂O₄-C@Al₂O₃ catalyst with a core-shell structure was synthesized. MnFe₂O₄-C@Al₂O₃ was characterized and applied in the removal of total nickel (T_Ni) and organic contaminants from actual ENPE, using a coupled system of HCO combined with a magnetic dithiocarbamate chelating resin (MnFe₂O₄-C@Al₂O₃/O₃-MDCR). Results show that embedding Al₂O₃ with C and MnFe₂O₄ significantly increased the T_Ni removal efficiency (99.3%), enhanced the O₃-utilization efficiency and improved the generation of reactive oxygen species (ROS). The reaction rate (k = 0.7641 min^-1) and O₃-utilization efficiency established for T_Ni removal (ΔT_Ni/ΔO₃ =0.221) by the MnFe₂O₄-C@Al₂O₃/O₃-MDCR system, were 220% and 140% higher than the Al₂O₃/O₃-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 ¹O₂ and •OH considered to the predominant ROS. Overall, these findings verify that the synthesized MnFe₂O₄-C@Al₂O₃ catalyst possesses excellent catalytic capabilities and outstanding structural stability, making it suitable for practical application in the treatment of wastewater effluent.