A Novel Magnetic-Mof-Based Hydrogel for Efficient Removal of Copper and Silver Ions in Electroplating Wastewater: Resource Utilization Observation

The electroplating wastewater containing hazardous metal ions such as copper ions (Cu2+) and silver ions (Ag+), has severely contaminated the water source. Herein, we rationally design and prepare a magnetic hydrogel named Fe3O4@UiO-66-NH2/CTS (chitosan)-PEI (polyethyleneimine). Thanks to the strong attraction of the amino group (-NH2) and metal cations, the incorporation of Fe3O4@UiO-66-NH2 and PEI advancing the adsorption effectiveness, the maximum adsorption capacities of Cu2+ and Ag+ ions around 321.67 mg·g-1 and 226.88 mg·g-1 within 120 minutes, respectively, which show the remarkable removal efficiencies by magnetic hydrogel. Based on experimental characterization and theoretical calculation, the competitive adsorption order of Cu2+, Ag+ and other metal cations are revealed. Furthermore, the optimal configuration of the CTS-PEI is discovered using density functional theory, and water retention of hydrogel is simulated with molecular dynamics modeling. The Fe3O4@UiO-66-NH2/CTS-PEI hydrogel has exceptional reusability and maintains 80% removal effectiveness after 5 cycles of adsorption- desorption. Finally, on the view of the utilization of resources, the Ag ions-accumulated hydrogel is treated via reduction reaction to generate Ag-doped photocatalyst, which exhibits the promising degradation efficiency for Rhodamine B. The novel magnetic hydrogel is prospected to efficiently remove heavy metal ions from the electroplating wastewater and further resource utilization.