A direct-current method
for measuring ion-exchange membrane resistivity
S. Nouri1, L. Chaabane2, L. Dammak2*
1 Unité de recherche Chimie des matériaux (02UR1201), ISSBAT. 9 Rue Dr. Zouheir Sefi, 1002, Tunis – Tunisie.
2 ICMPE. 2-8, Rue Henri Dunant. 94320 Thiais – France
* Corresponding author: E-mail: email@example.com
Received: 19 June 2009; revised version accepted: 08 September 2010
This paper deals with a method for measuring the electrical resistance of an ion-exchange membrane, RM, with the GUILLOU’s cell. The method is based on the application of a direct current and on the analysis of the potential jump (PJ) through the membrane, subsequent to the application of this current. The PJ was determined by the extrapolation of the potential difference to the initial time.
Experimental results obtained with three homogeneous commercial ion-exchange membranes (CM1, CM2 and CMx) show, on the one hand, that the shape of the curves RM versus the concentration of the equilibrating solution, measured at DC, is the same than that obtained at AC, and on the other hand, for all the membrane/solution systems, membrane resistance is higher at AC than that at DC. This difference was explained by the presence of two phenomena when we applied DC: electro-osmosis and the concentration polarization on the level of the gel-intergel interface. The effects of these phenomena are opposite. It appears that the effect of electro-osmosis is much more important than that of the internal polarization of the concentration. This is expected owing to the fact that the three membranes used are often regarded as homogeneous.
Keywords: Ion-exchange membrane; Electrical resistance; Cell; Direct current; Alternating current.