BINARY AND TERNARY CATION EXCHANGES : THERMODYNAMIC AND MASS ACTION
MODELINGS

Rhee, In H.

Environmental Engineering Research 1999;4(3): 207-222.

BINARY AND TERNARY CATION EXCHANGES : THERMODYNAMIC AND MASS ACTION MODELINGS

In H. Rhee^†

Department of Chemical Engineering, Soonchunhyang University, Asan 336-745. Chungnam

Corresponding Author: In H. Rhee ,

Received: March 6, 1999; Accepted: August 6, 1999.

ABSTRACT

Phcrmody namic and mass action models were lesled against a large data sel lor binary and ternary cation exchanges of Na, Mg. and Zn on a maeroreticular snllbiiate cation exchange resin in the various anionic media at two total cation concentrations ( l('C'). Model parameters were extracted from binary cation exchange data for the chloride medium at ICC'-0.05 N. Solution-phase speciation was included in the models. Thermodynamic models with the solid- and solution-phase activity corrections made by the Wilson and Duvies equations, respectively, provided good predictions of binary exchange and fair predictions of ternary exchange. Predictions were less accurate when the activity corrections for the solution phase species were calculated with the Pit/er equation. Among the conventional mass action models, the C iaines-1 homas model provided the best predictions of the binary and ternary cation exchange data. The Ciapon model provided significantly less accurate predictions. Despite their abilih to describe effects of anions on ion exchange, the predictions of the thermodynamic and mass action models were of limited accuracy, even for a simple solid containing a single charged group such as a resin file inaccuracy may relate to incomplete con¬sideration of microscale processes invoked in ion exchange, especially specific adsorption.

Keywords: binary and ternary cation exchange | thermodynamic and mass action models | solution-phase speciation. activity correction | specific adsorption