Dear Azri,

The answer is yes. NAFION membrane is water permeable. For details read the following:

Journal of Membrane Science 392–393 (2012) 88–94

Transport of liquid water through Nafion membranes

Qiongjuan Duana, Huaping Wanga, Jay Benziger b,∗

a College of Material Science and Engineering, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620, PR China b Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544 USA

a b s t r a c t

Theflux ofliquid water through Nafionmembranes of differentthickness and equivalent weight wasmeasured as a function of hydrostatic pressure and temperature. Hydraulic water transport across Nafion membranes increases with temperature and equivalent weight of the Nafion. Hydraulic permeability increases with temperature due to both decreased water viscosity and increased hydrophilic volume fraction. Convective flow from the applied hydrostatic water pressure is an order of magnitude greater than the estimated diffusive water flux associated with the water activity gradient. Water sorption and hydraulic permeability data predict a hydrophilic pore network with hydrophilic domains 2.5 nmin diameter spaced 5.5 nm apart. The pore network structure from water sorption and hydraulic permeability

are consistent with the spacing between hydrophilic domains observed with small angle X-ray scattering experiments.

To view the full publication, please use the following link:

http://pemfc.princeton.edu/Documents/Publications/LiqWaterThroughNafion_2012.pdf

Hoping this will be helpful,

Rafik

Dear Azri, 

I can guess you are talking about PEM Fuel cells.  Nafion membranes in these fuel cells should be semi permeable for water vapour. 

Nafion® is a copolymer of perfluoro-3,6-dioxa-4-methyl-7octene-sulfonic acid and tetrafluoroethylene (Teflon®). In simpler terms Nafion is a Teflon backbone with occasional side chains of another fluorocarbon. The side chain terminates in a sulfonic acid (-SO3H).

With the exception of the sulfonic acid group, Nafion is a fluorocarbon polymer. Like most fluoropolymers, it is extremely resistant to chemical attack (corrosion resistant). The sulfonic acid group is immobilized within the bulk fluorocarbon matrix and cannot be removed, but unlike the fluorocarbon matrix the sulfonic acid groups do participate in chemical reactions. The presence of the sulfonic acid adds three important properties to Nafion:

Nafion functions as an acid catalyst due to the strongly acid properties of the sulfonic acid group.

Nafion functions as an ion exchange resin when exposed to solutions.

Nafion very readily absorbs water, from the vapor phase or from the liquid phase. Each sulfonic acid group will absorb up to 13 molecules of water. The sulfonic acid groups form ionic channels through the bulk hydrophobic polymer, and water is very readily transported through these channels. Nafion functions like a very selective, semi-permeable membrane to water vapor.

For more information go to

http://www.permapure.com/resources/all-about-nafion-and-faq/

yes,l depending on the type of Nafion, you have also a certain water mass transfer through your  Nafion; bearn in mind that you have to hydrate the Nafion before using it. check with DuPont, they will provide you with the exact figures! 

Dear Azri,

Normally for PEMFCs, water should be formulated in the cathode side by the reaction between the passed hydrogen protons through the membrane, electrons coming from the external circuit and the oxygen (Air) flow in the air channels. This formulated water must be managed to keep the membrane saturated and transport the access with air flow outside. 

Usually, no water flow in the anode side (hydrogen feeding) and if water flooding to the anode side happens, this will cause a problem (hydrogen feeding blockage) affecting the cell performance.

Many papers are available regarding this topic but my suggestion is 

doi:10.1016/j.jpowsour.2007.04.020

Experimental investigation of liquid water formation and transport in a transparent single-serpentine PEM fuel cell

Dusan Spernjak , Ajay K. Prasad , Suresh G. Advani,

Best regards,

Aimen

http://www.sciencedirect.com/science/article/pii/S0378775307006982

Thank you for your accurate answer, I just forgot to tell you that I work on microbial fuel cells where the presence of aqueous media is mandatory, when checking my device I filled the anode chamber with the water some minutes later the water is found on the other side, in this case we can say that the membrane is permeable to water?

the device consists of two cylinder connected by a nafion membrane glued with silicone, the ends of cylinders are fastened with a hose.

thanks in advance

How can we estimate the Nafion membane permeability (m2) and porosity as a function of water content?