Development Of A Bipolar Electrochemical Flow Microreactor For Separate Electrodeposition Of Valuable Metals From Mixed Solutions

Recovery of valuable metals from electronic industrial wastes is an important subject for environmental and resource requirements.A combination of bipolar electrochemistry and flow electrolysis techniques is used to develop a novel bipolar electrochemical flow microreactor to separately deposit mixed metal ions onto different positions of a single bipolar electrode.The mixed ion solutions were injected into the upstream end of the cathode plate of the bipolar electrode at a certain flow rate,and then flowed to the downstream end of the bipolar electrode.The separate electrodeposition of different metal ions can be realized by adjusting the driving voltage,the velocity of the mixed solution,the length of the cathode plate,the composition and concentration of the mixed solution.The potential gradient along the electrode surface was studied as a function of driving voltage,background solution concentration,solution thickness and connecting hose length.FESEM-EDX analyses indicated that both a gold-copper alloy(ca.80 atom%Au)and pure copper were recovered from a solution containing 0.125 mM AuCl4-and 20 mM Cu2+.The underpotential deposition of Cu atoms on the overpotential-deposited Au atom layer led to formation of the gold-copper alloy.This work provides a new potential way to recover valuable metals from waste electronic materials.In addition,the potential electrocatalytic properties of the deposited Au/Cu alloy micro-nano particles were tested.The electrochemical kinetics of methanol electrooxidation reaction was measured in alkaline electrolyte,using the Au/Cu alloy deposits as the working electrode.