SORPTION OF AMINO ACIDS ON PHOSPHATE CATION EXCHANGERS

Abstract

Summary. Influence of the nature of a sorbent and acidity of solution of the irreplaceable coded amino acid – methionine on its interaction with phosphate ion exchangers KRF-5p and KF-7 in the protonated form with use of calorimetric, sorption and spectroscopic methods is studied. With use of the equations of isotherms of an ionic exchange, material balance and constants of dissociation of amino acid exchange and not exchange sorption capacities are calculated. It is established that irrespective of number of functional groups in a cell of a polymeric matrix, coefficients of sorption balance for both cation exchangers are close, and values of sorption capacity on anion of methionine are slightly higher, than in a bipolar form. The direct calorimetric method determined enthalpies of sorption of methionine at various extents of filling of an ion exchanger, is shown that at identical extents of filling of sorbents of an enthalpy of sorption is one KF-7 lower, than on KRF-5p. The conducted researches allowed to assume that from sour solution at low extents of filling the bipolar ion of methionine is absorbed, an ion of hydrogen of the protonated ion exchangers, not forced out in solution, and passes to carboxyl group of amino acid, neutralizing its negative charge. From the alkaline environment at low concentration of methionine ion-exchange sorption with transfer of a proton from ionogenic group of the cation exchanger to carboxyl group of methionine is most probable. It is established that sorption of amino acid is influenced, mainly, by an arrangement of active groups in a matrix of a sorbent and a form of the absorbed amino acid. It is shown that primary sorption centers are functional groups of ion exchangers, and additional – the absorbed amino acids.