Use of a Macrocyclic Crown Ether in an Emulsion (Liquid Surfactant) Membrane to Effect Rapid Separation of Pb 2+ from Cation Mixtures

Results for the carrier-mediated transport of Pb2+ from an aqueous solution through an emulsion-type liquid membrane to an aqueous receiving phase are presented. The carrier, dicyclohexano-18-crown-6, was initially dissolved in the oil phase. The process was studied with Pb(NO3)2 alone and with Pb(NO3)2 in the presence of either LiNO3 or KNO3. Lead recovery was over 90% with up to tenfold enrichment. Lead was preferentially transported over either Li+ or K+ providing rapid separations.