engleski

Removal of Heavy Metal Ions from Solutions by Means of Zeolites. II. Thermodynamics of the Exchange Processes Between Zinc and Lead ions from Solutions and Sodium Ions from Zeolite A

Relationships between the correlated selectivity coefficient, Kc(Me) (Me = Zn, Pb), and the fraction of the exchanged Me2+ ions in zeolite A, fMe,Z, were determined from the corresponding exchange isotherms. The exchange isotherms were obtained by measuring the equilibrium concentrations of sodium and Me2+ ions in both the solid and the liquid phase at constant total-ion concentrations and different temperatures in the range from 20 C to 60 C. Thermodynamic equilibrium constants Ka(Me), calculated from the corresponding Kielland's plots (lnKc(Me) vs. fMe,Z plots) were used for the calculation of the appropriate values of the standard free energy, deltaG0(Me), standard enthalpy, deltaH0(Me), and standard entropy, deltaS0(Me).

Zeolite A; Ion exchange; Sodium ions; Zinc ions; Lead ions; Exchange equilibrium; Thermodynamic data

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