Electrochemical performance of MnO2 films coated on Pb-Ag anode for zinc electrowinning
The Pb-Ag anode utilized in zinc electrowinning exhibits a high overpotential for oxygen evolution,leading to the facile dissolution of surface lead through electrochemical oxidation,thereby producing low-quality cathode zinc.To address this issue and mitigate lead pollution caused by anode dissolution of the Pb-Ag anode,enhancing its catalytic activity for oxygen evolution and reducing energy consumption during the electrowinning process is imperative.In this study,a uniform and compact MnO2 films electrodeposited onto the Pb-Ag anode surface.The morphology,crystal structure and solution lead content of the MnO2 catalytic layer were thoroughly characterized using SEM,XRD,and ICP techniques,respectively.Furthermore,the oxygen evolution catalytic activity and corrosion resistance of the Pb-Ag/MnO2 anode were evaluated by CV,LSV,EIS and Tafel electrochemical tests.The results show that,under optimal electrodeposition conditions(4 mA/cm2 for 120 min in MnSO4-H2SO4 electrolyte at temperature of 80℃and solution circulation rate of 200 mL/min),the Pb-Ag/MnO2 electrode exhibits superior performance in terms of both catalytic oxygen evolution and corrosion resistance.Specifically,after coating the Pb-Ag anode with MnO2 film under these optimized conditions,the oxygen evolution overpotential at 50 mA/cm2 decreases from 936 mV to 648 mV while simultaneously reducing corrosion current density from 7.03 μA/cm2 to 0.66 μA/cm2.Compared with the Pb-Ag anode,the dissolved lead content in the solution decreases significantly from 0.61 mg/L to only 0.29 mg/L after continuous long-term zinc electrowinning experiments lasting 15 d based on the Pb-Ag/MnO2 anode.
NETL
NSTL
万方数据
