The ion-exchange extraction of leucine by a liquid sulfocationite (a solution of dinonylnaphthalene sulfonic acid in octane) from NaCl aqueous solutions was studied over a wide range ofpH values and amino acid concentrations. The amounts of leucine absorbed in the Leu(+) and Leu(+/-) ionic forms were calculated. Over the pH range from 0.8 to 4.0, the liquid ionite exhibited a high selectivity for leucine; the factors responsible for this effect are discussed.

The ion-exchange extraction lysine from NaCl aqueous solutions with a solution of dinonylnaphthalenesulfonic acid in heptane was studied over wide ranges of lysine concentrations and pH values. Amounts of lysine absorbed as Lys(2+) and Lys(+) cations were calculated. A sharp increase in the selectivity with respect to the singly charged lysine cation at pH 2.5-4.0 was observed. It was shown that this effect is due to the interaction between the Lys(2+) and Lys(+) ions in the organic phase.

Ion-exchange extraction of glutamic acid from aqueous solutions of NaCl by a liquid sulfocationite (a heptane solution of dinonylnaphthalenesulfonic acid) was studied in a wide range of pH and amino acid concentration variations. The amounts of glutamic acid absorbed in the Glu(+) and Glu(+/-) ionic forms were calculated. Characteristics of the interactions of glutamic acid and valine with the liquid sulfocationite were compared (these amino acid molecules contain side radicals similar in size but different in their hydrophilic properties and have equal H+-Glu(+) and H+-Val(+) exchange selectivity coefficients on polymeric ionites). Valine extraction by the liquid ionite was found to be more selective than extraction of glutamic acid. The reasons for this are discussed.

Extraction of valine from aqueous solutions of NaCl with liquid sulfonic cation exchanger, a solution of dinonylnaphthalenesulfonic acid in heptane, was studied in a wide range of valine concentrations and pH values. The amounts of valine extracted as its cation and zwitterion are calculated. The optimal conditions for extraction and reextraction of valine are determined.

Equilibria of ion exchange of neutral aliphatic amino acid cations (A+ =Gly+, Ala+, Val+, Leu+) and H+ have been studied on a liquid sulfonic type ion exchanger — dinonylnaphthalene sulphonic acid dissolved in heptane. It has been established that the difference in selectivity of extraction of these cations is much greater than on sulphostyrene resins, which is a favourable precondition for their selective extraction. The selectivity coefficients of the H+–A+ exchange have a region of a low dependence on the degree of loading of liquid ion exchanger (X=0–0.5) and a region of a sharp decrease (X>0.5). This phenomenon is explained as a result of formation of very stable complexes of the amino acid cations and the anion of dinonylnaphthalene sulphonic acid containing one unsubstituted proton per 3–6 A+ cations. The IR spectra confirm this assumption. The dependence of the selectivity coefficient on the degree of H+–A+ exchange has been described using the previously developed mathematical model of ion-exchange processes. The model is consistent with the experimental data in an assumption that four nearest neighbours of an exchange centre in the associates of the liquid ion exchanger influence the energy of ion exchange on a given exchange site.

The biozones of cation exchanger component of ion-exchanger soils being in equilibrium with nutrient solutions of the total concentration of 0.0017, 0.017, 0.034 and 0.17 g-eq./l have been calculated.