Extraction of metal ions mixture cadmium, iron, zinc and copper from aqueous solutions using emulsion liquid membrane technique

Abstract

In the present work the process of extraction of cadmium, copper, zinc, and iron metal ions was studied using Emulsion Liquid Membrane (ELM) technique. Emulsion liquid membrane system depends on the preparation primary water-in-oil emulsion then emulsified the primary emulsion in water to produce double water-in-oil-in-water emulsion. Therefore three liquid phases will occurs: internal (receiving) phase, liquid membrane phase, and external phase. The internal and external phases are miscible with each other but separated by the membrane phase which is immiscible with both. The membrane was prepared by dissolving the extractant D2EHPA (di-2-ethylhexylphosphoric acid) used as a mobile carrier, and sodium dodecyl sulphonate, a surfactant, in kerosene. The internal (receiving) phase was prepared by dissolving sulfuric acid in water. The effect of variables: initial concentration of metal ions in the feed phase, surfactant concentration, carrier concentration, sulfuric acid concentration in the receiving (internal) phase, agitation time, volume ratio of the external feed phase to the primary water-in-oil emulsion, and pH of feed were studied on the percentage removed of metal ions in experiments carried out in a batch-type stirred vessel at 30 °C. The results showed that the percent removed of metal ions was in general increase with increasing of surfactant concentration, carrier concentration, sulfuric acid concentration in the internal phase, agitation time, and pH of feed and decrease with the volume ratio of the external feed phase to the primary water-in-oil emulsion. The results show that it is possible to recover 98 % of metal ions mixture.