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4261893 
Journal Article 
Simultaneous recovery of Zn and Mn from used batteries in acidic and alkaline mediums: A comparative study 
Abid Charef, S; Affoune, AM; Caballero, A; Cruz-Yusta, M; Morales, J 
2017 
1 
Waste Management
ISSN: 0956-053X
EISSN: 1879-2456 
68 
518-526 
English 
28669497 
WOS:000413126300052 
A parallel study of acidic and alkaline leaching for the recovery of Mn and Zn from spent alkaline batteries is outlined. Using H2SO4as solvent and selecting appropriate conditions of temperature and concentration, all residues were dissolved except carbon. The separation and recovery of the two components were performed by electrodeposition with satisfactory results at pH values above 4 (current efficiency above 70% for Zn and Mn) but rather lower efficiencies as the pH decreased. Most of the Zn was selectively dissolved by alkaline leaching using a 6.5M NaOH solution, and its recovery was examined by means of both electrochemical and chemical processes. The expected formation of pure Zn by electrowinning failed due to the formation of ZnO, the content of which was highly dependent on the electrodeposition time. For short periods, Zn was the main component. For longer periods the electrodeposit consisted of agglomerated microparticles of ZnO with a minor fraction of Zn metal (barely 3% as measured by X-ray diffraction). A chemical reaction of the element with oxygen released at the anode surface might be responsible for its conversion to ZnO. A simple chemical route is described for the first time for the direct conversion of Zn(OH)42-solution to nanostructured ZnO by lowering the pH to values around 12 using 2M HCl solution.