Cation-Exchange Membrane (CMI-7000S) for Electrolysis and Electrodialysis, CEECEMCMI7000S
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The CMI-7000S (also identified as CXM-200S) is a strong-acid cation exchange membrane produced by Membranes International Inc. It is a heterogeneous membrane, meaning it is composed of ion-exchange resin particles embedded within a polymer matrix, often reinforced with a woven fabric to enhance mechanical durability.
It is composed of polymer backbone of polystyrene cross-linked with divinylbenzene and functional group of sulphonic acid (-SO3^-). Due to its thickness and cost-efficiency, the CMI-7000S is rarely used in automotive fuel cells but is the primary choice for: (1) Electrodialysis (ED/EDR): Used for seawater desalination and demineralization of industrial process water. (2) Electrodeionization (EDI): Producing ultrapure water by combining ion exchange resins with membrane separation. (3) Metal Recovery & Electroplating: Used in cells for the recovery of metals from plating baths or waste streams. (4) Bio-Electrochemical Systems: Frequently cited in research for Microbial Fuel Cells (MFCs) and silver recovery systems due to its superior performance compared to its anion-exchange counterpart (AMI-7001S).
| Part Number | CEECEMCMI7000S (C-EE-CEM-CMI7000S) |
| Ion Type | Cation (–SO₃⁻) |
| Reinforcement | None |
| Thickness (um) | 450 |
| Ion Exchange Capacity (meq/g) | ~1.6 |
| Area Resistance (Ω·cm² in NaCl) | <30 |
| Operating pH | 1-10 |
| Operating Temperature | up to 90 °C |
| Pre-treatment Required | Soaking 12–24h |
| Primary Applications | Electrolysis; Electrodialysis, Electrodeionization, Bioelectrochemical System |
| Package Grade | 10cm*10cm/pcs/pack (other sheet size of 20cm*20cm, 30cm*30cm, 40cm*40cm also can be supplied upon request) |
Use Note:
(1) The CMI-7000S is shipped dry Sodium (Na^+) form. To avoid mechanical failure and ensure ionic conductivity, it must be properly hydrated before installation: Immersion: Submerge the membrane in a 5% NaCl solution or the intended application solution. Duration: Allow it to soak for at least 12 hours. Expansion: During this time, the membrane will hydrate and expand. Always precondition before cutting to your final cell dimensions, as it can expand significantly.
Reference:
- H. Tang, et al., Influence of Membrane Ion Sorption on Ammonium Transport in Donnan Dialysis with Cation Exchange Membranes, ACS EST Engg. 2026, 6, 2, 909–919.
- N.A.D. Ho, et al., Bio-electrochemical reactors using AMI-7001S and CMI-7000S membranes as separators for silver recovery and power generation, Bioresource Technology, 2017, 244, 1006-1014.