Electrodeposition of γ-MnO2 from manganese nodule leach liquor: Surface modification and electrochemical applications

Abstract

The electrolytic manganese dioxide (EMD) production through electrodeposition from manganese nodules by reduction leaching in H2SO4 medium using sucrose as reductant followed by purification through 2-stage precipitation methods is described. The purified leach liquor was the starting solution for electrodeposition. Influence of in situ addition of a cationic surfactant Cetyltri-methylammonium bromide (CTAB) (0–500 mg dm−3) on the surface morphology and electrochemical properties of the EMD was examined. The XRD patterns of the deposited material were indexed to the γ-MnO2 phase. FESEM results demonstrated that in the presence of CTAB uniform nano-fibrous type grains were formed. Higher concentration of CTAB in the electrolytic bath however, drastically decreased the current efficiency (CE) and increased the energy consumption (EC) during electrodeposition. Under the optimum CTAB concentration of 100 mg dm−3 the obtained CE and EC values were 87.64% and 1.70 kWh/Kg respectively.