Anion-Exchange Membrane (Fumasep, FAS Series) for Electrodialysis, Electrolyzer and Fuel Cell, CEEFCAEMFAS

The Fumasep FAS series is a family of hydrocarbon-based anion exchange membranes (AEMs) produced by Fumatech BWT. Unlike the FAA series, which is optimized for alkaline electrolysis and fuel cells, the FAS series is the industry standard for standard electrodialysis (ED) and water desalination. These membranes are characterized by high permselectivity and a robust polyaromatic backbone that offers excellent stability in neutral to slightly alkaline or acidic solutions.

FAS-30 and FAS-50 (Non-Reinforced): These are homogeneous polymer films without an internal fabric mesh. They offer the lowest electrical resistance because 100% of the cross-section is active ion-exchange material, which makes them ideal for high-precision laboratory experiments. However, they are mechanically delicate and can "wrinkle" or swell significantly if not hydrated properly before assembly.

FAS-PET-75 and FAS-PET-130 (PET Reinforced): These membranes feature an internal woven Polyethylene Terephthalate (PET) mesh that acts as a skeleton. In large-scale industrial stacks (which can be over 1 meter in height), non-reinforced membranes would sag or stretch under the weight and flow of the water. The PET reinforcement ensures the membrane stays flat and maintains its dimensions. These membranes are significantly more resistant to tearing during the manual assembly and tightening of a plate-and-frame stack.

Use Note:

Proper preparation is critical to prevent the membrane from failing mechanically once the stack is turned on.

(1) Peel the Foil: FAS membranes are delivered on a clear PET backing foil. You must carefully peel the membrane away from this plastic before use.

(2) Hydration (Crucial): These membranes are shipped dry (usually in the Cl- form). They must be soaked in 0.5 M NaCl or the target electrolyte for 24 hours before installation.

Warning: If installed dry, the membrane will swell upon contact with the process water, causing it to buckle and potentially leak or cause an internal short circuit.

(3) Storage: Store in a 0.5 M NaCl solution. For long-term storage, add a small amount of preservative (like sodium sulfite) to prevent biological growth (algae/mold) on the polymer surface.

References:

1. Z. Liu, et al., The effect of membrane on an alkaline water electrolyzer, Int. J. Hydrogen Energy, 2017, 42, 29661-29665. 
2. J. G. Hong, et al., Electrochemical characterizations and reverse electrodialysis performance of hybrid anion exchange membranes for salinity gradient energy, J. Electroanalytic Chem., 2018, 817, 134-140.