Extraction of zinc and copper-zinc mixtures from ammoniacal solutions into emulsion liquid membranes using LIX 84I®

Emulsion liquid membranes with LIX84I as extractant were used to extract zinc and copper-zinc mixtures from ammoniacal media. The effects of various emulsion parameters and process parameters on zinc extraction were investigated. The optimal pH was 8.1. The stripping rates were found to be slower than the loading rates in ELMs. The extraction and stripping data using LIX84I were obtained for Zn and Cu-Zn mixtures to discern the influence of individual steps on ELM extraction. A synergistic effect was observed for loading and stripping zinc in the presence of copper. Zinc stripped faster than copper when the zinc concentration was higher or comparable with copper. Separation factors for Cu/Zn were found to be in the range of 1.1-1.4. When Cu-Zn mixtures were extracted in ELMs, it was observed that the whole extraction process was governed by the loading of copper and zinc in the membrane phase and other considerations such as stripping, diffusion etc. were completely masked by the rapid loading rates of copper in the ELMs. The separation factor beta(Cu/Zn) was found to be a maximum of 3.5 indicating the possibility of selective separation of copper from Cu-Zn mixtures using ELMs. (C) 2009 Elsevier B.V. All rights reserved.