TRANSFER MECHANISM OF TETRAALKYLAMMONIUM IONS ACROSS A WATER-NITROBENZENE INTERFACE AND THE STRUCTURE OF THE DOUBLE-LAYER

The transfer of tetraalkyl (from tetraethyl to tetrapentyl) ammonium ions (R+) from water to nitrobenzene is investigated by means of chronopotentiometric measurements. The systems studied are formed by an aqueous solution of R+Br- with an excess of NaBr as supporting electrolyte. These aqueous phases are in contact with a nitrobenzene solution of 10-2 M or 10-3 M tetraphenyl borate of the same R+ ion. Electrocapillary results obtained previously, with the same systems, suggest that the interfacial charge distributions are only spread within the diffuse layers, showing a continuity of the electrical potential across the central layer. Starting from this point a treatment has been proposed to deduce from the chronopotentiometric results the values of the ion transfer rate constants and how the central layer is affected by the overvoltage. In some regions of overvoltage, discrepancies are observed between these values and those calculated from electrocapillary curves. © 1979 Elsevier Sequoia S.A.