Diffusion of alkali and alkaline earth chlorides through a parchment-supported silver iodide membrane

Abstract

Diffusion rates of KCl, NaCl, LiCl, BaCl₂, CaCl₂, and MgCl₂ through a parchment-supported silver iodide membrane have been measured at various temperatures using a constant flow method. Activation energies and various Eyring activation parameters for the diffusion of these electrolytes have also been evaluated. The diffusion rate sequences obtained are KCl > NaCl > LiCl and BaCl₂ > CaCl₂ > MgCl₂ and they point towards the weak field strength of the membrane fixed charged groups. Diffusion coefficients and the various Eyring activation parameters have been related to the ionic hydrated sizes and the various thermodynamic quantities of ionic hydration thus emphasizing the importance of ion hydration in diffusion across the membrane.