An ion-exchange process with thermal regeneration. VI. Factors influencing the titration curve shape of weak electrolyte resins

Abstract

An experimental study is presented which establishes that if the titration curve of a weak electrolyte resin is to exhibit a well-defined pH plateau, it must have a structure which is homofunctional and which is not too polar. Homofunctional mono- and di-alkylamino groups in a cross-linked hydrocarbon polymeric structure exhibit such a plateau. Polymers with non-polar backbones and primary amino or carboxyl groups possess sloping titration curves. The results can be accounted for by the formation of ion pairs with monovalent counter ions in the less polar structures, or with multivalent counter ions in more polar structures.