Electrochemical recovery of total Cr by reduction alongside immobilization using an acethydrazide functionalized Fe/Ni-MIL-53 MOF electrode

Electrochemical reduction and immobilization of Cr(VI) were rendered using a special Fe/Ni-MIL-53 MOF-electrode. The target Fe/Ni-MIL-53 (Acethydrazide) was in situ grown from a nickel foam through redox between Fe3+ and Ni0 and solvothermal treatment with acethydrazide as 1,4-benzene dicarboxylic acid's modulator. On account of the acethydrazide, the bimetallic metal-organic framework evolves from nanorods into out-stretched nanoflakes. At -1.2 V, using the self-supporting Fe/Ni-MIL-53 (Acethydrazide) as cathode, the efficiency of reducing Cr(VI) is 3.1 times higher than Fe/Ni-MIL-53. By virtue of the large surface area and -NHNH2 moiety, Fe/Ni-MIL-53 (Acethydrazide) promptly renders the complete removal of total chromium from treated water, which is also efficient in removing Cr(VI) in actual electroplating wastewater. The Cr adsorbed on the electrode can be recovered by a process including pickling and precipitation. This work points out a new direction for preparing novel MOF and the application in removing and recovering heavy metal ions.