Several mixtures of butyl acetate (BA) and an ionic liquid (1-methyl-3-octylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [CCPyrro][NTf], 1-octyl-pyridinium bis(trifluoromethylsulfonyl)imide, [CPyr][NTf], 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide, [CCIm][NTf] or 1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide, [CCIm][NTf]) have been characterized by measuring density, viscosity and conductivity, from pure BA to pure ILs at 298.15 K. The ionicity of these mixtures has been determined on the basis of electrical conductivity and NMR spectroscopy. IR spectra of these mixtures were used to examine the interactions between ions. In parallel, Pt(iv) was extracted from the acidic aqueous phase towards mixtures of BA and [CCIm][NTf] over the entire composition range. A drastic modification in the distribution coefficient of Pt(iv) was observed at ca x = 0.8. A drop was also observed in the ionicity of the extracting phase (IL + BA) at a similar composition. The variation of the distribution coefficient is ascribed to changes in the interactions in the mixtures, which in turn could induce changes in the extraction mechanism.

The effect of three water-soluble, unsubstituted crown ethers (1 5-crown-5 (1 5C5), 18-crown-6 (18C6) and 21-crown-7 (21C7)) on the uptake of Ca, Sr, Ba and Ra cations by a sulfonic acid cation exchange resin, and on the extraction of the same cations by xylene solutions of dmonylnaphthalenesulfonic acid (HDNNS) from aqueous hydrochloric acid solutions has been investigated. The crown ethers enhance the sorption of the larger cations by the ion exchange resin, thereby improving the resin selectivity over calcium, a result of a synergistic interaction between the crown ether and the ionic functional groups of the resin. Similarly, the extraction of the larger alkaline earth cations into xylene by HDNNS is strongly synergized by the presence of the crown ethers in the aqueous phase. Promising results for intra-Group IIa cation separations have been obtained using each of the three crown ethers as the aqueous ligands and the sulfonic acid cation exchange resin.Even greater separation factors for the radium -calcium couple have been measured with the crown-ethers and HDWS solutions in the solvent extraction mode. The application of the uptake and extraction results to the development of radium separation schemes is discussed and a possible flowchart for the determination of 226Ra/22sRa in natural waters is presented.