Mixed liquid ion exchangers

EXTRACTION OF SALTS BY MIXED LIQUID ION EXCHANGERS Gabriella Schmuckler and Gideon Harel... 

Figure 2 Distribution isotherms of calcium and magnesium chlorides, at 25°C, between aqueous and mixed liquid ion exchanger dissolved in toluene (0.5 M TOA + 0.5 M 2-ethylhexanoic acid).

The reaction between the metal salt and the mixed liquid ion exchanger differs materially from that of the anionic complex. In that case the process taking place is not one of ion exchange but of solubilization of the neutral salt, ML2 ... 

Figure 13 Water solubilization as a function of the mixed liquid ion-exchangers concentration (dissolved in toluene).

Figure 18 High-frequency IR spectra of—OH stretching vibrations of copper-chloride—loaded mixed liquid ion exchangers at different copper concentrations. Concentrations of CuCb (a) 0 (b) 0.05 m (c) 0.010 m (d) 0.025 m (e) 0.041 m (f) 0.061 m.

The functional groups of rhodamine B (two tertiary amines and one carboxylate) integrate well into the small reversed micelles formed by tri-octylammonium 2-ethylhexanoate in toluene. Figure 19 shows the fluorescence emission spectra of various CaCb concentrations solubilized in 0.5 M mixed liquid ion exchanger in the presence of rhodamine B. The excitation wavelength was set at 546 nm and the emission intensity was measured at 574 nm. 

In order to determine the selectivity coefficient experimentally, a special unit, consisting of three compartments, was built for measuring the potential difference between two aqueous solutions containing two ions at different concentration ratios. The central compartment contained the liquid membrane, that is, the mixed liquid ion exchangers dissolved in a diluent. The reference solution—in the left compartment—was a mixture of K1 and KCl, the total concentration was kept constant at 0.001 m. Specimens of the same mixture but of different [1 ]/([ ] + [Cl ]) ratios were introduced in the right compartment, and the potential difference between the two solutions was measured with the aid of two identical Ag/AgCl refer-... 

In the present work measurements were made of molar conductivity versus concentration of several electrolytes dissolved in a mixed liquid ion exchanger and a diluent of low polarity. 

Conductivity measurements of other salts (LiCl and NaCl) dissolved in the mixed liquid ion exchangers showed the same pattern as illustrated in Fig. 23 and supported the assumption that the sharp rise in conductivity is due to proton transfer from the ammonium ion to amine molecules. 

Mixed liquid ion exchangers of the free-base amine and carboxylic acid type dissolved in a solvent of low polarity proved to be excellent extractants for alkaline earth and transition metal salts from aqueous solutions. 

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