低浓度下离子交换树脂吸附氨基酸的机理

MECHANISM OF UPTAKE OF AMINO ACID ON ION EXCHANGE RESIN IN DILUTE SOLUTIONS

详细地研究了在低浓度下,酸(碱)式或盐式强酸性阳离子和强碱性阴离子交换树脂吸附氨基酸的机理·结果表明,氨基酸通过离子交换、离子转移和物理吸附等三种机理被离子交换树脂吸附。

The uptake of glycine by 001×7, a strong acid cation exchange resin and 201×7, a strong base anion exchange resin at low concentration as a function of the solution pH has been investigated in detail, The test of equivalence law for the uptake of glycine and the release of counter-ion from the ion exchange resin, and the in-frared spectroscopy of glycine adsorbed on the 001×7 resin were used to eluciderethe mechanism of uptake of amino acid on ion exchange resin from aqueous solution.The uptake of glycine on styrene-divinybenzene copolymer has been examined too. The uptakes of seven amino acids (Gly, Phe, Lys, Len, Ala, Thr, Glu,) bythe 001×7 resin in H form at low solution concentration as a function of pH havebeen determined too, and it was found that the maximum uptake of amino acids takesplace in the pH range close to the isoelectric points, the heights of the maximumuptake of the neutral amino acids are related to the second macroscopic dissociationconstants,and the height of the maximum upke of phenylalanine is higher than that of glycine in 50%. On the basis of experimental data it can be concluded that the uptake of amino acid by strong acid cation and stroug base anion exchange resins proceeds according tothe stoichiometric exchange mechanism, ion (proton, sodium ion, chloride et al.)transfer mechanism and physical adsorption mechanism. The physical adsorption forcemay be neglectable for glycine, and become significant with higher of molecularweight and size of the amino acid.