Mechanochemically Enhanced Cu(II) and Ni(II) Capture from Wastewater via Lattice Incorporation

We introduce a mechanochemical strategy to achieve efficient removal and lattice entrapment mechanism of Cu(II) and Ni(II) from wastewater with a custom-made mechanochemical reactor. It shows the potential of a paradigm shift from conventional metal removal to high-efficiency resource recovery for heavy metal wastewaters. Overcoming the surface reduction constraints inherent to nanoscale zerovalent iron (nZVI), the mechano-chemistry of microscale zerovalent iron (mZVI) (MC + mZVI) harnesses the mechanical energy to unite chemical bonding and lattice integration. This system achieved removal rates that exceed those of nZVI by factors of 3.0 and 5.7 for Cu(II) and Ni(II), respectively. In addition solid residues in the reaction products reached 73.5% Cu and 27.5% Ni (molar ratios). E_h-pH analyses provide evidence that the solution chemistry and stability of the resulting solid products under mechanochemical conditions. X-ray diffraction (XRD) validates the formation of Fe₄Cu₃, CuFeO₂, and NiFe₂O₄ crystalline phases within 120 min, while X-ray absorption spectroscopy (XAS) suggests the single-electron reduction of Cu(II) to form Cu(I)-O bonds and the integration of Ni(II) into NiFe₂O₄ via Ni(II)-O bonds. With exceptional scalability and stability, this approach can significantly reduces metal rerelease risks (<0.5% Cu, <0.3% Ni), offering an efficient and sustainable framework for heavy metal wastewater treatment and resource recovery.