Process intensification of copper extraction using emulsion liquid membranes: Experimental search for optimal conditions

Emulsion liquid membranes (ELMs) can contribute to process intensification of copper extraction, by significantly reducing the solvent and carrier requirements in comparison with conventional solvent extraction. This investigation reports the extraction of copper into emulsion liquid membranes using LIX 84 as carrier. The influence of four emulsion composition variables, namely the internal phase volume fraction (ϕ), surfactant concentration (Wsurf), internal phase stripping acid concentration (Cio) and the carrier concentration (Cc) as well as three process parameters pH, initial solute concentration (Ceo) and treat ratio (TR) on the rates of extraction of copper, was studied. The emulsions used were characterized on the basis of internal drop size distribution and viscosity to set a benchmark for the commercial application of this technology.It was found that extraction was favorable above pH 2, extraction rates pass through maxima with increase in carrier concentration and treat ratio. Increase in stripping capacities either by increase of ϕ or increase in Cio enhanced the extraction rates. Effect of variables on emulsion swelling were investigated; data suggest that entrainment swelling of emulsion was predominant. Swelling was observed to be serious only after 30 min of contact between the emulsion and the feed phases. Optimal conditions for the successful implementation of ELM extraction of copper on commercial scale are suggested.