Mechanism of metal ion transport in polystyrene based cobalt phosphate membrane and application of absolute reaction rate theory

Manoj Kumar* and Satish Chand

Department of Chemistry, Hansraj College, University of Delhi, Delhi-110007, INDIA

Email: kushwah205@gmail.com

Abstract:

The conductance of polystyrene based cobalt phosphate membrane in contact with various alkali metal chlorides at different concentrations and temperatures has been measured. The conductance values of the investigated electrolytes have been found to follow the sequence K⁺>Na⁺>Li⁺. The absolute reaction rate theory has been applied to investigate the mechanism of transport of simple metal ions through the membrane. The thermodynamic parameters Ea,  and  have been evaluated along with inter-ionic distances. The activation energies for electrolyte conduction to follows the sequence of crystallographic radii of alkali metal cations. The energy decreases with increase of concentration of bathing electrolyte. It is thus concluded that membrane is weakly charged and ionic species retain their hydration shell at least partially, while diffusing through the membrane. The values of  were found to be negative, indicating that partial immobilization of the ion takes place. It is proposed that this is due to interstitial permeation and ionic interaction with the fixed charge groups of the membrane. Scanning Electron Microscope (SEM) micrographs of the membrane have also been presented.

Keywords: Membrane conductance, effect & concentrations and temperatures, thermodynamic parameters Ea, SEM micrographes.