Cation Transport at 25°C from Binary Cd 2+ –M n + Mixtures in a H 2 O‐CHCl 3 –H 2 O Liquid Membrane System Containing a Series of Macrocyclic Carriers[1]

Macrocycle‐mediated fluxes of Cd(NO 3 ) 2 and of several binary mixtures of Cd(NO 3 ) 2 with the nitrate salt of either Na + , K + , Rb + Cs + , Ag + , Ca 2+ , Sr 2+ , Pb 2+ , Zn 2+ , or Cu 2+ have been determined in a H 2 O‐CHCl 3 –H 2 O liquid membrane system. Of the macrocycles studied, 2.2 and 2.2DD most successfully transported Cd 2+ In the Cd 2+ –M n + mixtures, Cd 2+ was transported selectively with 2.2 when M n + was either an alkali or an alkaline earth cation. However, when M n + was either Ag + , Pb 2+ , or Cu 2+ the Cd 2+ flux was reduced sharply. Generally, cation flux was greater for 2.2DD than for 2.2 with selectivity for Cd 2+ being altered also in several cases. Relative fluxes from binary cation mixtures depend on metal cation radius, macrocycle cavity diameter, ligand ring substituent and log K for metal ion‐macrocycle interaction.