Tetrabutyl, ammonium, alkali or uranyl ions and their electrochemical transport behaviour in 2,2,2 trifluoroethanol; a study to contribute to basic research on the reprocessing of nuclear fuels

This study has been intended to determine single-ion conductivities of Bu4N+, I-, Br-, and their solvation numbers in water-free TFE by means of combined conductivity and transfer measurements at 250C. The measurements have been done in order to obtain information on the impact of the -I-effects of the F3C group on the solvation performance of this solvent in comparison with that of the simple aliphatic alcohols, and also because these measurements make it possible to exactly deduce ion mobility data from the conductivity data obtained by the experiments using TFE. The concentration dependence of the Bu4N+ transfer numbers has been measured applying the autogenous interface method using CoI2 and CoBr2 as indicators, with concentrations between 10-2 and 4.10-3 mol/l. Transfer numbers measured by optical methods have been extrapolated to infinite dilutions by means of the Stokes function and the Longworth function. From these measurements and from the equivalent conductances published by Evans et al. the single-ion conductivities of Bu4N+, Br-, and I- have been determined for an ionic strength of I -> O, from which the mobilities of the Bu4N+, I- and Br- in TFE can be calculated. The single-ion conductivities of Bu4N+, I- and Br- can also be used to determine the single-ion conductivities of the alkali, ammonium and halide ions, using the TFE conductivity data according to Kohlrausch, and for deducing the solvation numbers of the salts as the following step. In addition, the equivalent conductance of KF, KNO3, RbCl, UO2(NO3)26H2O, and UO2(NO3)22H2O in the solvent have been measured for concentrations > 10-5 mol/l. Evaluation of the measured results with a view to uranyl nitrate salts has been done applying the Fuoss Kraus method. (orig./RB)