Hannu Paananen

STUDY ON THE RETENTION OF GLYCINEBETAINE ON A WEAK ACID CATION EXCHANGE RESIN

Weak acid cation (WAC) exchange resin in monovalent form is used in the recovery of glycinebetaine (GB) under alkaline conditions. The resin can also be used as a stationary phase at pH below the resins pKa value, that is, in hydrogen form, when the retention behavior of GB is essentially different. In this study, the retention mechanism of GB was investigated on a WAC exchange resin in hydrogen, sodium, and intermediate ionic forms and with three other components: glycerol, choline chloride, and glycine. The experiments were carried out in a pilot scale column with acrylic acid-divinylbenzene gel type resin with aqueous eluent at neutral and acidic pH. GB was reported to retain notably longer on a hydrogen form WAC resin than on a corresponding sodium form exchange resin. Similar changes in retention time were seen for glycine, but not for glycerol or choline chloride. It was concluded that the retention mechanism of GB on the hydrogen form WAC exchange resin is related to hydrogen bonds between the resin and zwitterionic GB. The greater retention of GB on hydrogen form WAC resin can be utilized, for example, in the recovery process of GB from acidic solutions, such as vinasse.