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Ion exchange membranes are semipermeable membranes that separate dissolved ions in a liquid. Depending on the membrane’s electric charge, they allow certain ions to pass through while blocking others.
Ion exchange membranes are used in manufacturing processes that require treatment and purification. Membrane technology is more cost-effective than evaporation technology because it is not energy-intensive, and it does not require a high capital expense. In addition, ion exchange membranes can be used in processes like zero liquid discharge (ZLD) that are proven to reduce environmental impact.
How Do Ion Exchange Membranes Work?
Ion exchange membranes have ionic perm-selectivity, meaning they have preferential permeation of certain ionic species. Because of this selectivity, they can be classified into cation or anion exchange membranes. Cation exchange membranes, which primarily consist of negatively charged groups (anions), prevent anions from passing through the membrane while allowing positively charged groups (cations) to pass through. Anion exchange membranes perform the opposite way, rejecting cations while allowing anions through. These selective permeations are carried out by direct current during electrodialysis.
AGC offers a variety of cation and anion exchange membranes under the brand name FORBLUE™ SELEMION™ so that you can select the specific grade that is best for your application. Your selection can be based on thickness, counterion, burst strength, durability, resistance, transport number, proton leakage, temperature, exposure to alkali, etc.
Ion exchange membranes are ideal for applications such as:
- Water treatment and desalination
- Food demineralization
- Purification of organics
- Valuables recovery when etching or plating
- Acid recovery
- Table salt production
- Industrial wastewater reclamation (ZLD)
- Substitutional reactions
- Redox reactions
- Electro organic synthesis
Ion Exchange Membranes vs. Ion Exchange Resins
What’s the difference between ion exchange membranes and ion exchange resins? The answer is regeneration. Both ion exchange membranes and ion exchange resins behave similarly. Ion exchange resins are granular and perform an adsorptive exchange of ions. However, they require regeneration once they reach adsorptive capacity. Ion exchange membranes, on the other hand, allow ions to permeate by direct current and do not require regeneration, allowing for continuous use for extended periods of time.
Ion exchange membranes dilute and concentrate ionic materials with electro/diffusion dialysis. SELEMION ion exchange membranes are an improvement over conventional ion exchange resins that use a stack of ionic particles with binder resins to connect the particles. This is because these hydrocarbon-type membranes are made from organic polymer materials that form a homogeneous film that is more perm-selective.
For more information on incorporating FORBLUE SELEMION ion exchange membranes into your application, contact an AGC representative