Thermodynamics of the Na(I)–H(I), K(I)–H(I) and Ca(II)–H(I) exchanges on zirconium(IV)aluminophosphate cation exchanger

The equilibrium exchange of Na(I), K(I) and Ca(II) ions with the hydrogen form of zirconium(IV) aluminophosphate has been studied at 30 and 60 °C. On the basis of the exchange isotherms, various thermodynamic parameters such as equilibrium constants (K°), standard free energy (ΔG°), entropy (ΔS°) and enthalpy (ΔH°) changes during the exchange reaction have been calculated. A correlation has been made of these parameters with the ion exchange characteristics of the material.