Cation Transport from Multiple Alkali Cation Mixtures Using a Liquid Membrane System Containing a Series of Calixarene Carriers

Article abstract of DOI:10.1021/ja00287a012

Several new p-tert-pentylcalixarenes have been synthesized.These and other calixarenes have been used to study carrier-mediated alkali-metal cation fluxes at 25 deg C in H2O-(organic solvent)-H2O liquid membranes.In addition to single cation systems, all possible equimolar, two-, three-, and four-cation mixtures of NaOH, KOH, RbOH, and CsOH were used in the study.In each case, alkali cation transport was coupled with the reverse flux of protons.Selective transport of Cs(1+) over Rb(1+), K(1+), and Na(1+) was seen in all mixtures studied.The greatest selectivity for Cs(1+) was found for calix<4>arenes, but the largest flux of Cs(1+) as well as the other alkali cations was seen with the calix<6>arenes and calix<8>arenes.The greater flux in these latter cases may be a result of each calixarene binding two cations.In experiments at low -to- ratios, p-tert-butylcalix<6>arene transports Rb(1+) over Cs(1+).As these ratios increase, transport of Cs(1+) becomes favored over that of Rb(1+), indicating that the cation flux depends, in part, on the relative concentrations of the cations in the source phase.