Cation-Exchange Membrane (Fumasep, FKB, FKD, FKE, FKL) for Electrodialysis and Electrodeionization, CEECEMFK
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The Fumasep F-series (FKB, FKD, FKE, FKL) is a specialized range of hydrocarbon-based cation-exchange membranes produced by Fumatech BWT. Unlike the perfluorinated "F-10" series (which compete with Nafion), these grades are designed for electrodialysis (ED), diffusion dialysis (DD), and bipolar membrane (BPM) stacks. The primary difference between these grades is their selectivity (which ions they allow through) and their blocking capability (which ions they stop).
The FKB series (eg: FKB-PK-130) is a specialized cation membrane with high proton conductivity but extremely high resistance to hydroxide (OH-) crossover and its main application is Bipolar Electrodialysis (EDBM). It is used as the cation-selective layer in a bipolar stack to produce acids and bases from salts. It allows H+ or Na+ to pass but prevents OH- from the neighboring chamber from crossing over, which would ruin the efficiency of the acid production.
The FKD series (eg: FKD-PK-75) is specifically optimized for Diffusion Dialysis (DD), a process used to recover free acids from waste streams (like spent pickling liquors in steel plants). Its primary application is acid recovery. It has a very high permeability for protons (H+) but a very low permeability for metal cations (like Fe2+, Zn2+, or Cu2+). This allows the pure acid to diffuse through the membrane into a water stream while leaving the heavy metal contaminants behind.
The FKE series (eg: FKE-50) is the "standard" high-performance grade for water treatment where purity is the priority. It is mainly used for Electrodialysis (ED) and Electrodeionization (EDI). It is designed to have an exceptionally high selectivity (typically >98%). It is very efficient at separating monovalent cations (Na+, K+) from the feed stream with minimal "water transport" (osmosis).
The FKL series (eg: FKL-PK-130) is designed for applications where energy consumption is the most important factor. Its primary application field is general desalination and wastewater treatment. It has a higher water uptake and a slightly lower polymer density than the FKE, resulting in lower electrical resistance. This reduces the voltage required to run the electrodialysis stack, saving power in large-scale industrial plants.
| Part Number | CEECEMFKBPK130 | CEECEMFKDPK75 | CEECEMFKE50 | CEECEMFKLPK130 |
| Name | FKB-PK-130 | FKD-PK-75 | FKE-50 | FKL-PK-130 |
| Thickness (um) | 115-150 | 70-80 | 48-57 | 120-140 |
| Reinforcement | Yes (PEEK Mesh) | Yes (PEEK Mesh) | None (Self-supporting) | Yes (PEEK Mesh) |
| Area Resistance (Ω·cm²) | <10 | <2 | 1.48-1.57 | 3-10 |
| Selectivity | >98.5% | >97% | 98.5% | 96%-99% |
| Typical Use Case | Bipolar Electrodialysis | Diffusion Dialysis | Electrodialysis (ED) & Electrodeionization (EDI) | Electrodialysis |
| Package Grade | 10cm * 10cm/pcs/pack | 10cm * 10cm/pcs/pack | 10cm * 10cm/pcs/pack | 10cm * 10cm/pcs/pack |
Use Note:
(1) Delivery Form: These membranes are delivered dry and are attached to a clear PET backing foil. You must peel the membrane off the foil before use.
(2) Reinforcement: Grades with "PK" in the name are reinforced with a PEEK (Polyetheretherketone) mesh. These are much stiffer and more durable than the non-reinforced "plain" versions.
(3) Hydration: For all these grades, it is recommended to soak the membrane in the target electrolyte (or 0.5 M NaCl) for at least 24 hours before assembly. This allows the polymer to reach its "swollen" equilibrium size so it doesn't wrinkle inside the cell frame.