NEW METHOD TO DETERMINE THE TRUE TRANSMISSIBILITIES AND PERMEABILITIES OF OXYGEN IN HYDROGEL MEMBRANES

In the present paper, an electrochemical method to obtain the true tra nsmissibilities and permeabilities of hydrogels to oxygen is proposed. The method involves the measurement of the electric current arising f rom the flow of oxygen through a potentiostat cell integrated by a top water layer, the hydrogel membrane, and a thin water layer between th e membrane and the cathode, where the oxygen is reduced. Varying the t hickness of the top water layer, the true permeation characteristics o f the hydrogels are obtained. A parallel study was carried out in whic h the transmissibilities and permeation coefficients were obtained fro m the variation of the steady state current with the thickness of the membranes. The permeation results obtained by the two methods agree ve ry satisfactorily. The method also permits to determine the values of the transmissibility of the water layers of the experimental set-up. ( C) 1998 Elsevier Science Ltd. All rights reserved.