Recovery of manganese from spent alkaline batteries: use of MnOx as catalyst for VOCs elimination

LORENA FALCO; MARIA VICTORIA GALLEGOS; MIGUEL A. PELUSO; JORGE E. SAMBETH; HORACIO J. THOMAS

Mendoza

Congreso; V Conferencia Internacional sobre Análisis de Ciclo de Vida 24 y 27 de marzo de 2013 en Mendoza, Argentina.; 2013

The waste batteries cause a serious concern due to their toxicity, abundance and permanence in the environment. The bio-hydrometallurgical processes have higher efficiency, lower cost and few industrial requirements. Bioleaching generally allows efficient release of metals from solid phase into aqueous solution under mild conditions such as room temperature and pressure in the presence of sulfur-oxidizing bacteria. One of the final products of a biohydrometallurgical process for the recovery of metals from spent alkaline and Zn-C batteries is a manganese oxide. Manganese, in the form of oxide, was recovered from alkaline batteries employing a biohydrometalurgy process, using a pilot plant reactor, contained a reducing acid medium produced by an Acidithiobacillus thiooxidans bacteria immobilized onelemental sulfur.  Two different manganese oxides were recovered from the leacheate liquor, one by electrolysis (EMO) and other by a chemical precipitationwith KMnO4 solution (CMO). The non-leaching solid residue was also studied (RMO).  The characterizations reveal the presence of Mn2O3 in the EMO and the CMO samples, together with some Mn4+ cations. In the solid not extracted by acidic leaching (RMO) the main phase detected was Mn3O4. The catalytic performance of the oxides was studied in the complete oxidation of ethanol and heptane.  Complete conversion ofethanol occurs at 200 °C,while that of heptane requires more than 400 °C.The CMO has the highest oxide selectivity toCO2.             The results show that manganese recycled can be used as catalyst in VOC oxidation process.