TRANSFER OF ALKALI-METAL IONS ACROSS THE WATER-NITROBENZENE INTERFACE FACILITATED BY POLY(OXYETHYLENE)DODECYL ETHERS

The transfer behaviour of alkali metal ions across the water-nitrobenzene interface facilitated by nonionic surfactants poly(oxyethylene)dodecyl ethers (C12E(x)) were investigated by means of cyclic voltammetry. The results show a linear dependence of the reversible half-wave potential DELTA(n)(w)phi(1/2) on the logarithm of the concentration of alkali metal ions in the aqueous phase. Therefrom, the apparent free energy change of ion transfer facilitated by C12E(x), DELTA(n)(w)G(tr)0, was determined. The results indicate that the ion transfer facilitated by C12E(x) is attributable to the formation of a hydrophobic complex of alkali metal ion with C12E(x) and its ion pairs with the counter anion, and the rate of transfer is controlled by the diffusion of C12E(x) from the bulk nitrobenzene phase to the interface.