Diffusion of water in Nafion 115 membranes

In this paper, experimental and simulated data for the diffusion of water a cross Nafion membranes as a function of the water activity gradient are pre sented. The gradient in the activity of water across the membrane was varie d by changing the flow rate and pressure of nitrogen gas on one side of the membrane. The other side of the membrane was equilibrated with liquid wate r. It was found that the model predictions are very sensitive to the value of the diffusion coefficient of water in Nafion. Using the Fickian diffusio n coefficient extracted from self-diffusion measurements reported in the li terature, the model simulations matched experimental data with less than 5% error over a wide range of operating conditions. (C) 2000 The Electrochemi cal Society.