Cation-Exchange Membrane (Fumasep, FKS Series) for Electrodialysis and Electrodeionization, CEECEMFFKS
Use your own shipping account?
We support FedEx, UPS, and DHL third-party billing for institutional customers.
Place your order first, then email shipping@echemsupplies.com with your account details and order number. We'll generate the label using your account and refund your shipping charges, less a handling fee.
The Fumasep FKS series is a family of hydrocarbon-based, monovalent-selective cation-exchange membranes (CEMs) manufactured by Fumatech BWT. The FKS series is the industrial standard for electrodialysis (ED) and water treatment. These membranes are characterized by their high permselectivity and excellent mechanical stability in aqueous solutions.
FKS-30 and FKS-50 (Non-Reinforced): They are ideal for high-precision laboratory experiments where you want to measure the pure electrochemical properties of the polymer. However, they are fragile without reinforcement and can swell or "wrinkle" more easily if not hydrated correctly.
FKS-PET-75 (PET Reinforced): The mesh acts as a skeleton, preventing the membrane from stretching or sagging in large industrial frames. It is the go-to choice for commercial water demineralization.
FKS-PK-130 (PEEK Reinforced): PEEK is far more chemically and thermally stable than PET. This membrane is designed for aggressive environments (very low/high pH) or high temperature electrodialysis where other membranes would degrade or lose their shape.
| Part Number | CEECEMFFKS30 | CEECEMFFKS50 | CEECEMFFKSPET75 | CEECEMFFKSPET130 |
| Name | FKS-30 | FKS-50 | FKS-PET-75 | FKS-PET-130 |
| Thickness (um) | 24-34 | 48-54 | 74-87 | 120-140 |
| Reinforcement | No (Self-Supporting) | No (Self-Supporting) | Yes (PET) | Yes (PET) |
| Ion Exchange Capacity (IEC), (meq/g) | 1.3-1.6 | 1.35 | 1.0-1.25 | - |
| Area Resistance (Ω·cm², Na⁺) | <1.2 | <1.6 | <2.0 | <3.0 |
| Selectivity | >96.5% | >97.5% | 96.0% | 96.0% |
| Tensile Strength (MPa) | >30 | >32 | >45 | >80 |
| pH Stability | 1-14 | 1-14 | 0-9 | 0-9 |
| Features | Ultra-low resistance; very thin. | High selectivity; balanced flux. | Robust; dimensional stability. | Maximum durability; thick. |
| Typical Use Case | Lab-scale electrodialysis; high-flux research. | Standard desalination; EDI | Industrial ED stacks; wastewater. | Heavy-duty industrial; high pressure (harsh conditions). |
| Package Grade | 10cm * 10cm/pcs/pack | 10cm * 10cm/pcs/pack | 10cm * 10cm/pcs/pack | 10cm * 10cm/pcs/pack |
Use Note:
(1) Peel the Foil: These membranes are delivered on a clear PET backing foil. You must carefully peel the membrane away from this plastic before use.
(2) Hydration (The 24-Hour Rule): FKS membranes are shipped dry. They must be soaked in 0.5 M NaCl or your target electrolyte for 24 hours before assembly.
Warning: If installed dry, the membrane will swell upon contact with liquid, causing it to buckle and potentially short-circuit the cell or cause leaks.
(3) Storage: Dry form: Keep in the original packaging, away from UV light.
Wet form: Store in a 0.5 M NaCl solution with a small amount of preservative (like sodium sulfite) to prevent algae/mold growth.