Effect of Temperature on Ion-Exchange Equilibria in Mixed Solvents Involving Alkali Ions on Cation-Exchange Resin

F. H. Kamal, A. S. Aboul-Magd, A. M. Barakat And A. R. Ebaid

Department of Chemistry, Faculty of Science, Al-Azhar University, Nasr City, Cairo Egypt

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ABSTRACT:

Equilibrium constants of Li+, Na+ and K+ exchanges on novol styrene butadiene Ph-formal-dehyde cation exchange resin (H+-form) (SBPF) in aqueous-methanol mixtures have been calculated at temperature 25°, 35° and 45°C. The thermodynamic equilibrium constant are found to be increases with increase in temperature and with methanol concentrations. The parameters Δ G° free energy changes, Δ H° enthalpy changes and the corresponding values of entropy changes Δ S° have been calculated for each exchange as well at each solvent compositions. The variation of the thermodynamic functions with methanol compositions showed that, the Δ S° changes which determine the selectivities in mixed solvent systems, rather than enthalpy changes which controls the selectivities in aqueous medium.

KEYWORDS:

Ion-Exchange; Equilibria