Abstract: The general procedure is developed with which the intrinsic dissociation constants of weakly acidic and basic ion exchange resins can be determined without assuming the activity coefficient of M⁺(or X^-) ion equal to that of H⁺(or OH^-) ion in the resin phase. The procedure is based on the application of the Donnan membrane equilibrium equation and the extrapolation.In this paper, the intrinsic dissociation constant of the weakly basic anion exchange resin D705 was determined, and the water sorption, electrolyte sorption and titration curve of the resin D705 are studied in conjunction with the varying degree of neutralization.

Key words: Weakly basic anion exchange resin, Apparent dissociation constant, Intrinsic dissociation constant