The influence of side substituents in α-amino acids on their sorption by a cation-exchange membrane

The isotherms of sorption of ornithine, lysine, arginine, and histidine by an MK-40 membrane were obtained by the method of variable concentrations. The influence of the geometric parameters of side groups in the basic amino acids and pH on the degree of their absorption by the membrane was studied. The formation of doubly charged amino acid cations in the membrane phase when membranes in the H+ form were used was substantiated IR spectroscopically. The distribution coefficient was found to depend linearly on the size of amino acid side groups. The dependence of interphase surface tension at the membrane-solution interface on the degree of membrane filling was indicative of the formation of sorbate associates in the membrane phase.