Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
The transfer of proton, alkali, and alkaline earth metal ions across the water/nitrobenzene interface, facilitated by a synthetic neutral dicarboxamide ionophore in the nitrobenzene phase was investigated using cyclic voltammetry. The ionophore-facilitated transfer of Li+, Ca2+, and Ba2+ ions showed cathodic current peaks, and the transfer of H+ ions apparently resulted in peaks of both anodic and cathodic currents within the potential window. The transfer process of these ions was found to be controlled by the diffusion of the ionophore in the nitrobenzene. The formation of a 1 : 1 complex for H+ and of 1 : 2 (cation to ionophore) complexes for Li+, Ca2+, and Ba2+ ions was inferred, through peak separation or the dependence of the cathodic peak potential on the logarithm of the ionophore concentration, to be involved in the transfer process. The equilibrium constants KLI,M for the exchange reaction of the ion MZ+ with the Li-+ ionophore complex at the water/nitrobenzene interface were evaluated and correlated with the potentiometric selectivity coefficients KLi,MPot.
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