Ion exchange membranes are essentially a class of polymeric membranes containing functional groups capable of exchanging ions. Their core structure can be divided into three parts: a polymeric backbone, immobilized ionic groups, and mobile counterions. Completely different material systems are selected for different applications. Ion-exchange membranes serve a single core function: they allow only specific charged ions to pass through while blocking other ions or molecules.(This article was written by Dongsheng Precious Metals Recycling Company.)
Article Contents
How to Select Ion Exchange Membrane?
What are the different types of ion exchange membrane?
Materials Used in Different Ion Exchange Membranes and Their Applications
Detailed Information on Ion Exchange Membrane Manufacturers
Perfluorosulfonic Acid Membranes (Proton Exchange Membranes)
Electrodialysis/Bipolar Membrane Sector
Selecting an ion exchange membrane is not about choosing the highest value from a spec sheet, but rather about matching the membrane to the composition of your feed solution and operating conditions. First, confirm whether the feed solution contains free chlorine, strong oxidizing agents, or organic solvents, as these three factors directly determine whether you must use perfluorosulfonic acid membranes or can opt for the more cost-effective hydrocarbon membranes. Next, consider temperature: long-term operation of hydrocarbon membranes at temperatures exceeding 40°C accelerates the detachment of sulfonic acid groups and the swelling of the membrane matrix. In such cases, you must upgrade to perfluorinated membranes or PTFE-reinforced membranes. Current density requirements determine the selection range for membrane surface resistance. For electrodialysis desalination aimed at low energy consumption, select products with a surface resistance between 2 and 4 Ω•cm². If the salt concentration is concentrated to 150 g/L or higher, prioritize whether selectivity can still be maintained at 90% or above. Ion exchange membranes must undergo static immersion testing with the actual feed solution, particularly for bipolar membrane acid and alkali production operations, to measure the decay in iron ion contamination flux over 24 hours.
There are five types of ion exchange membranes: perfluorosulfonic acid membranes, homogeneous hydrocarbon anion exchange membranes, homogeneous hydrocarbon cation exchange membranes, heterogeneous membranes, and bipolar membranes.
Perfluorosulfonic acid membranes are the most chemically stable ion exchange membranes of all types. They can withstand long-term exposure to free chlorine concentrations as high as 0.5 mg/L without degradation. Typical thickness ranges from 25 to 180 micrometers, and proton conductivity can exceed 0.1 S/cm at 80°C under fully wetted conditions. They remain stable across the entire pH range from 0 to 14.
Homogeneous hydrocarbon cation exchange membranes use sulfonated styrene-divinylbenzene or sulfonated polyetheretherketone as the substrate. Their ion exchange capacity ranges from 1.6 to 2.4 meq/g, and their surface resistance ranges from 1.5 to 5 Ω• cm², and they typically tolerate a pH range of 1 to 13. The continuous operating temperature does not exceed 40°C, and their selective permeability in a standard sodium chloride system exceeds 93%.
Homogeneous hydrocarbon anion exchange membranes utilize quaternary ammonium groups immobilized on a polystyrene or polysulfone backbone. The anion migration number is generally 0.95 or higher; however, alkali resistance varies significantly among brands. In standard-grade membranes, quaternary ammonium groups undergo Hoffmann elimination and degradation when the pH exceeds 12, whereas alkali-resistant modified versions can withstand 5% sodium hydroxide at 40°C for short periods.
Heterogeneous membranes are produced by calendering ion exchange resin powder (200–400 mesh) with a polyethylene or polypropylene binder. The membrane resistance is typically 5 to 15 Ω•cm², and the burst strength is only 0.2 to 0.4 MPa; however, the cost can be one-third to one-fifth that of homogeneous membranes, making them suitable for primary brackish water desalination and applications that do not require high selectivity.
Bipolar membranes are produced by hot-pressing a cationic membrane layer, an anionic membrane layer, and an intermediate catalytic layer together. Their water dissociation voltage ranges from 1.0 to 1.2 V, and their current efficiency can reach 95% to 98% at 800 A/m². They are the only ion-exchange membranes capable of generating H⁺ and OH⁻ in situ under an electric field.
Perfluorosulfonic acid membranes are produced by copolymerizing tetrafluoroethylene with perfluorosulfonylfluoroethylene ether to form perfluorosulfonic acid resin, which is then extruded from a melt or cast from a solution to form the membrane; reinforced versions are produced by impregnating an ePTFE microporous mesh with perfluorinated resin. Ion exchange membrane manufacturers use these membranes in chlor-alkali electrolysis to produce 32% caustic soda, in PEM water electrolysis to produce green hydrogen, in proton exchange membrane fuel cells for power generation, and in all-vanadium flow batteries to isolate the anode and cathode electrolytes. Homogeneous carbon-hydrogen anode membranes are produced by dissolving sulfonated polystyrene-divinylbenzene copolymer or sulfonated polyetheretherketone in DMF or NMP and casting the solution; with an internal polyester mesh reinforcement. They are used in electrodialysis for brackish water desalination, seawater pre-concentration to 180 g/L total dissolved solids (TDS) for salt production, the conversion of organic acid salts into organic acids, and the desalination of amino acid fermentation broths. Homogeneous hydrocarbon anion exchange membranes are produced by chloromethylating polystyrene-divinylbenzene and then quaternizing it with trimethylamine. They serve as anion-selective barriers in diffusion dialysis for recovering free acids from steel pickling waste liquid and in the concentration of high-salinity electrodialysis wastewater for zero-discharge applications. Heterogeneous membranes are produced by compounding and calendering finished cationic and anionic exchange resin powders with polyethylene. They are used in applications with less stringent membrane performance requirements, such as primary desalination of municipal water and the recovery of effluent from cooling circulation water. Bipolar membranes, on the other hand, are composite structures consisting of hydrocarbon anion and cation exchange layers sandwiching an interfacial catalytic layer of polyethyleneimine or titanium dioxide. They are used for the direct regeneration of sulfuric acid and sodium hydroxide from sodium sulfate wastewater, as well as for the electrodialytic conversion of sodium gluconate into high-purity gluconic acid.
Chemours (U.S.) — Nafion™
The industry’s “gold standard”: The inventor and undisputed leader in perfluorosulfonic acid membranes, offering the most comprehensive product line that covers everything from chlor-alkali to fuel cells and flow batteries
Unparalleled chemical stability: Decades of industrial validation; resistant to strong acids, strong alkalis, and strong oxidizing agents; its lifespan and reliability serve as benchmarks for competitors
Disadvantages: Expensive; significant dry and wet deformation (non-reinforced types); supply is sometimes affected by export controls
Characteristics: High performance, but also the highest cost.
Gore (U.S.) — Gore-Select®
The pioneer and leader in reinforced composite membranes: By impregnating ePTFE microporous membranes with perfluorosulfonic acid resin, it resolves the issue of significant dry and wet deformation in pure membranes.
Extremely high market share in automotive fuel cells: Long-standing preferred supplier for mass-produced hydrogen vehicles such as the Toyota Mirai and Hyundai NEXO.
Ultra-thin and highly conductive: Capable of producing extremely thin membranes (tens of micrometers), with excellent proton conductivity and high mechanical strength.
Positioning: The company does not sell pure membranes but rather “reinforced composite membranes,” establishing a differentiated competitive strategy from Chemours
Asahi Kasei (Japan) — Aciplex™
One of the two global duopolists in chlor-alkali membranes (alongside Chemours), with decades of expertise in the production of caustic soda via the electrolysis of brine
Possesses unique advantages in membranes for seawater desalination and concentration; nearly all electrodialysis-based salt production in Japan uses Aciplex
Proton exchange membrane products also cover fuel cells, offering robust performance and occupying a key position in Japan’s domestic supply chain
Features: Comprehensive technology portfolio, ranging from chlor-alkali membranes to fuel cell membranes to electrodialysis membranes
AGC Asahi Glass (Japan) — Selemion™ / Forblue™
Another Japanese giant in perfluorinated membranes, forming a duopoly in the domestic market alongside Asahi Kasei
Its chlor-alkali membranes (Flemion series) have a long history, making it one of the leading suppliers to the chlor-alkali industry
The Selemion series of electrodialysis membranes offers outstanding resistance to acids, alkalis, and organic solvents, with unique applications in material separation
Features: Strong material R&D capabilities, covering both perfluorinated and hydrocarbon electrodialysis membranes, with a broad product line
Solvay (Belgium) — Aquivion®
The only major supplier of short-chain perfluorosulfonic acid membranes (all others use long-chain membranes)
Natural advantages in high-temperature, low-humidity conditions: Short-chain membranes have high glass transition temperatures and high crystallinity, maintaining good proton conductivity even under low-humidity/high-temperature conditions
Niche applications: Suitable for high-temperature PEM fuel cells, specialized electrolytes, and other scenarios with demanding operating conditions
Characteristics: Competitive differentiation through a distinct technological approach
ASTOM (Japan) — Neosepta®
The “gold standard” for electrodialysis membranes: Holds the highest global market share in the electrodialysis sector and offers the most comprehensive product line
Comprehensive coverage: Standard anion and cation exchange membranes, single-valent selective membranes, acid- and alkali-resistant membranes, bipolar membranes, and diffusion dialysis membranes—all available
Excellent stability: Long operational lifespan in industrial settings with slow performance degradation; considered the “safe bet” for electrodialysis projects
Disadvantages: High price, long lead times, and occasionally unstable supply to the Chinese market
Characteristics: For electrodialysis applications prioritizing reliability and performance, ASTOM is the top choice
Fumatech (Germany) — fumasep®
A high-end, German-manufactured non-fluorinated membrane brand specializing in homogeneous and bipolar membranes
Exceptionally high acid resistance: Stability and longevity in concentrated acid environments are key selling points
Mature bipolar membrane product line, with models available from laboratory to industrial scales
Features: Focuses on high-end, customized solutions for specialized applications with stringent performance requirements
Chemours supplies the full range of Nafion proton exchange membranes. The enhanced Nafion XL achieves a tensile modulus of over 300 MPa at 100% moisture content. According to publicly available quotes on platforms such as Membranes International, the price per square meter for standard-thickness Nafion 117 membranes ranges from $800 to $1,200.
Gore’s Gore-Select reinforced composite membrane has been installed in more than 40,000 units across mass-produced fuel cell vehicles such as the Toyota Mirai and Hyundai NEXO. The membrane thickness can be reduced to 12 micrometers while maintaining an extremely low hydrogen permeation current density. Asahi Kasei’s Aciplex chlor-alkali membranes can operate in zero-polarity electrolysers with a cell voltage controlled below 3.0 V for over four years without replacement. Ion-exchange membrane manufacturers offer two formulations—low-voltage and high-strength—for different operating conditions.
ASTOM’s Neosepta ACS cathode membrane and CMX anode membrane achieve current efficiencies of over 92% in industrial electrodialysis operations, serving as benchmark products for desalination and concentration projects. The water dissociation voltage of the BP-1E bipolar membrane is stable at below 1.1 V, and the monovalent selective anode membrane CIMS has a selectivity coefficient for monovalent cations exceeding 100.
Fumatech’s Fumasep FAS series anion exchange membranes exhibit low sulfonic acid leakage rates in strongly acidic environments with pH levels ranging from 0 to 2. When paired with acid-blocking anion exchange membranes, FBM bipolar membranes can limit impurity acid migration to less than 0.2% in organic acid production. Dongyue Future Hydrogen Energy’s DF988 proton exchange membrane, which matches the thickness specifications of Nafion 211, has passed durability testing exceeding 6,000 hours under fuel cell operating conditions.
Suzhou Kerun’s Nepem-1200 flow battery membrane controls vanadium ion permeability to below 5×10⁻⁷ cm²/min in a 1.6 mol/L vanadium electrolyte.
Beijing Tingrun’s homogeneous anion exchange membrane JCM-15 and homogeneous cation exchange membrane JAM-15 maintain stable pressure drop across the membrane stack in industrial electrodialysis concentration projects. The bulk supply price of the bipolar membrane JBM-1 is approximately $1,800 to $2,500 per square meter, which is 30% to 40% lower than that of imported membranes of the same specifications.
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