Efficient decomplexation and synergistic recovery integration: pathways and mechanisms for resource recovery of Ni-EDTA complex wastewater

Nickel (Ni) is an essential strategic non-ferrous metal widely used in electroplating, aerospace, new energy batteries, and chemical industries. However, the increasing demand for nickel, coupled with limited ore reserves and rising mining difficulties, has intensified resource scarcity. Meanwhile, industries such as electroplating, integrated circuit manufacturing, and new energy battery production discharge substantial amounts of nickel-containing wastewater, particularly Ni-EDTA complex wastewater. Owing to their six-coordinate chelate structure, Ni-EDTA complexes exhibit ultra-high stability (lgK = 18.56) and fluidity, enabling them to resist conventional neutralization and precipitation processes. This not only causes valuable nickel resource loss but also poses severe environmental and health risks, as Ni-EDTA is difficult to biodegrade and can accumulate in the environment, leading to organ damage and ecotoxicity. Thus, the decomplexation and resource recovery of Ni-EDTA wastewater have become critical challenges and research hotspots in industrial wastewater treatment.