Extraction of cadmium from aqueous solutions by emulsion liquid membranes using a stirred transfer cell contactor

It is studied the extraction of cadmium( II) ions from acidic aqueous solutions using a stirred transfer cell-type emulsion liquid membrane ( ELM) prepared by dissolving in kerosene, with D2EHPA ( an alkylphosphoric acid) as mobile carrier and Span-80 as surfactant. The ELM allowed efficient metal transport from the feed solution to the stripping liquor in experiments carried out at 25 C. The significant variables on cadmium transport through the membrane were extractant concentration and metal content in the feed metal-donor solution. Concentration of HCl as stripping agent affected only the initial metal extraction rate but not the extraction extent. The surfactant content used in this study stabilized the membrane adequately, but the use of a higher content produced a smaller initial extraction rate due to higher interfacial resistance. The experimental results suggest the possibility of recovering or removing valuable or toxic metals from dilute aqueous solution in an extractor based on emulsified liquid membranes.