American Journal of Polymer Science and Technology 2016; 2(2): 28-33 http://www.sciencepublishinggroup.com/j/ajpst) doi: 10.11648/j.ajpst.20160202.12 Studies with Model Membrane: Determination of Fixed Charge Density of Silver Sulfite Membrane Khaled Muftah Elsherif 1, * , Maisson Mohammed Yaghi 2 1 Chemistry Department, Faculty of Science, University of Benghazi, Benghazi, Libya 2 Chemistry Department, Faculty of Arts and Science, University of Benghazi, Benghazi, Libya Email address: elsherif27@yahoo.com (K. M. Elsherif), rajaeyaghi@yahoo.com (M. M. Yaghi) *Corresponding author To cite this article: Khaled Muftah Elsherif, Maisson Mohammed Yaghi. Studies with Model Membrane: Determination of Fixed Charge Density of Silver Sulfite Membrane. American Journal of Polymer Science and Technology, Vol. 2, No. 2, 2016, pp. 28-33, doi: 10.11648/j.ajpst.20160202.12 Received: September 17, 2016; Accepted: November 10, 2016; Published: December 5, 2016 Abstract: Parchment-supported silver sulfite membrane has been prepared by the interaction method. The membrane potential across the membrane in contact with different 1:1 electrolytes has been measured. The experimentally measured membrane potential values were used to evaluate the thermodynamically effective fixed charge density of the membrane- electrolyte systems using Teorell, Meyer, and Sievers (T. M. S.), Altug and Hair, and Kobatake et. al. theories. The values of effective charge densities were quite low (they were in order of 10 -2 – 10 -3 eq/l) and hence very difficult to determine by usual exchange methods. The values of effective charge densities by different theories were the same order of magnitude for each membrane-electrolyte system. The theoretical predictions for membrane potential were borne out quite satisfactorily by experimental results obtained with the membranes. Apparent transference numbers of coions and permselectivity values of the membrane-electrolytes have also been calculated. A method based on permselectivity values for determination of charge density was also used. It was interesting to note that the charge densities evaluated from two methods of Kobatake and co- workers gave similar values and that the results were comparable to those derived from the TMS method. Keywords: Membrane Potential, Fixed Charge Density, Permselectivity, Parchment Supported Membrane 1. Introduction Large amount of interesting works have been published for developing new membranes with desired properties, on account of their utilization for the economic separation processes. In this regard ion-exchange membranes have emerged as the most advance and economical separation membranes. These membranes are being widely used for the processes like electro dialysis of sea water or brackish water, separation of inorganic toxic metal ions, pharmaceutical products, sugar processing and beverages industries [1–5]. A variety of membranes can be constructed whose structure is well defined and whose permeation mechanisms and particular parameters can be varied in a controlled manner. By correlating structure and ion permeation in such membranes, it should be possible to develop experimental criteria for determining the structure, and hence the mechanism of ion permeation through an unknown membrane. In an attempt to develop these criteria a number of inorganic precipitated membranes [6–9] have been prepared with ion exchange sites and have studied the extent to which their chemical and transport properties depend on various external forces such as different chemical environments, temperature etc. The ionic selectivity of a membrane and the concentration range of the external salt solution in which its cationic behavior is shown both depend strongly on the fixed charge concentration of the membrane. The membrane fixed charge density can be determined using several methods: analytical titration [10], streaming potential measurements [11], and membrane potential measurements [12, 13]. In previous works, we have studied different parchment-supported membranes in order to evaluate the fixed charge density and to study the permeation of different electrolytes [14-20]. In this paper, we describe the preparation of silver sulfite parchment supported membrane. The effective charge density which is considered as the most effective parameter controlling the membrane phenomena, have been determined by the different methods using