Effect of temperature on membrane potential and evaluation of thermodynamic parameters of parchment supported silver thiosulphate

Membrane potentials for silver thiosulphate parchment supported membrane at different temperatures (30-60oC) have been measured. Experimental results were analyzed on the basis of the Kobatake equation. An increase with temperature of mobility ratio of the ions in the membrane phase (u+/u-) has been found and the following order exists: NH4Cl > KCl > NaCl. The activation thermodynamics parameters; enthalpy of activation ΔH‡, entropy of activation ΔS‡ and free energy of activation ΔG‡, have been estimated. The values of ΔS‡ are found to be negative indicating that diffusion takes place with partial immobilization in the membrane phase

Author(s): Khaled Muftah Elsherif , Ashraf El-Hashani and Abdelmeneim El-Dali

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