Preparation and Characterization of Manganese and Zinc Oxides Recovered from Spent Alkaline and Zn/C Batteries Using Biogenerated Sulfuric Acid as Leaching Agent

摘要

Manganese, zinc and mixed manganese-zinc oxides were synthesized after a biohydrometallurgical process to recycle alkaline and Zn/C batteries. A mixture of alkaline and Zn/C batteries was leached with biogenerated sulfuric acid. The effect of pulp density, time and use of additives, namely, H~(2)O~(2)and Na~(2)SO~(3), was studied. Using an S / L ?=?0.04?g?ml_(?1), 2?h, 5?vol.% H~(2)O~(2)or 1?wt.% Na~(2)SO~(3)at 30°C and in one step, 99% Zn and 90–98% Mn were extracted. After leaching, manganese (MnO~( x )) and zinc oxides (ZnO) were obtained by sequential precipitation first with KMnO~(4)and then with Na~(2)CO~(3), recovering 90% Mn and 95% Zn. Additionally, a mixed manganese-zinc oxide was obtained by precipitation with NaOH until pH?=?8 (ZM) recovering 28% Mn and 95% Zn. The Mn/Zn ratio was higher for the MnO~( x )catalysts. Characterization by x-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed the presence of α-MnO~(2)in MnO~( x )with globular shape, wurtzite in ZnO oxide with spherical shape and a mixture of ZnO wurtzite and ZnMn~(2)O~(4)in the ZM sample with platelet-type shapes.