Sorption of Ampholytes in Weakly Acidic Ion Exchangers: Effect of Resin Ionic Form on Betaine Uptake

Abstract

In this article, sorption mechanisms of glycine betaine and some related compounds on a weak cation exchanger has been studied. The effect of resin ionic form on the distribution coefficients was measured and the results correlated with a model including ion exchange, specific adsorption, and non-specific partitioning. Model calculations suggest that the maximum in the betaine uptake curve is predominantly due to ion exchange. Adsorption of the protonated and zwitterionic forms of betaine was included to improve correlation with experimental data away from the maximum. Assumptions made in the model were tested against uptake data of other model compounds.

Keywords:

• surface complexation theory
• modeling
• weak acid cation exchange resin
• ampholyte
• betaine