MATHEMATICAL-MODELING OF ION-EXCHANGE EQUILIBRIA ON RESINOUS ION-EXCHANGERS

A mathematical model establishing relations between selectivity, struc ture and ionic composition of an ion exchanger is proposed. A number o f nearest neighbours in the micro-environment of the exchange site has been chosen as a structural parameter. This number together with the local composition determines the exchange site micro-state. Different thermodynamic properties of ion exchange systems (e.g., DELTAH and DEL TAG) can be computed by summation of the relative micro-state properti es. The probabilities of the presence of a different number of nearest neighbours in the micro-environment of an exchange site in the sulpho styrene resins were estimated by the molecular dynamics method. An equ ation ''property-composition'' was derived and proved to be adequate t o the experimental data for the ion exchange with inorganic and organi c univalent ions on sulphostyrene resins over a wide range of cross-li nkage.