Estimation of the Binding Constant of Sugar Alcohol to Sodium Ion by Using Its Apparent Distribution Coefficients to Cation-exchange Resins with Different Cross-linkages

The apparent distribution coefficients, Kapp, of some sugar alcohols to cation-exchange resins in the sodium-ion form and with divinylbenzene (DVB) contents of 2, 4, 6, and 8% were measured at 25ºC. Assuming that the binding constant, B, of ribitol to sodium ion was zero, the swelling pressures, Π, of the resins in sodium-ion form with DVB contents of 2, 4, 6, and 8％ were estimated to be 3.2, 9.4, 12.3, and 25.7 MPa, respectively. From these Π values and Kapp values, the B values of each sugar alcohol were calculated. Because the B value is independent of the degree of cross-linking of the resin, the B values were obtained from the Kapp for resins with different DVB contents and were averaged. Erythritol and sorbitol had almost zero binding affinity to sodium ion. Among the tested sugar alcohols, the B values were in the order of xylitol > d-arabitol, l-arabitol > mannitol.