Veolia Water Technologies & Solutions

Ionics Ion Exchange Membranes

Ionics ion exchange membranes are homogeneous ion exchange films cast in sheet form on reinforcing synthetic fabrics such as polypropylene and polyester cloth. The membranes are typically used in Ionics ED and EDR stacks but are also available for sale individually.

Ionics* membranes are made with monomer formulations developed by our membrane chemists cast continuously on various support structures. They are each selective for allowing either anions or cations to pass through them. Veolia Water Technologies & Solutions has been making homogeneous ion exchange membranes for 70 years since the invention of the technology by Ionics Corp. in 1948.


General Membrane Characteristics

  • Low electrical resistance
  • High permselectivity
  • Rugged construction and high burst strength
  • Excellent long-term stability up to 70°C
  • Long-term resistance to aqueous acid solutions
  • High dimensional stability
  • High resistance to fouling by organic materials


Ionics ion exchange membranes have certifications below. See individual membrane fact sheets for specific certifications.

  • NSF 61 - Drinking Water
  • 21CFR175,176,177,178,182 – Food Contact Materials
  • EU 1935/2004 – Food Contact Materials
  • EU 10/2001 - Food Contact Materials
  • BSE/TSE EMEA/410/1 – No Materials of Animal Origin

Membranes by Application

Organic Fouling Resistant Membranes

AR103 and CR61 provide stability in high pH environments where aggressive cleaning with caustic solutions is needed along with organic material fouling resistance. These membrane chemistries have been used for more than 50 years for applications in the food and beverage industry, most prominently in the demineralization of cheese whey. Ionics invented the process for demineralizing cheese whey with electrodialysis in the 1950s, and Veolia still provides new equipment and membranes for customers in this industry

Standard Water Membranes

Ionics AR204 and CR67 membranes have the widest total footprint globally. They have been the primary membrane used in water desalination electrodialysis applications for 30 years. They are a cost-effective, scaling resistant membrane with resistance to chlorine, are NSF approved, and in water desalination applications can have a lifetime of 15 years or more. They can also be used for low organic fouling process applications.

Bipolar Membranes

Ionics Bipolar membranes are used in electrodialysis applications where salts are converted into acid and caustic product streams or where pH of process solutions can be adjusted. These membranes have two layers; one cation-selective and one anion-selective layer. The AR103 and CR61 are the primary options for the layers of the bipolar membrane. The anion layer is treated with a catalyst to aid in the water splitting function of the membrane.

Acid Blocking Anion Membranes

Bipolar Electrodialysis applications which convert salt solutions into separate product streams of acid and caustic, use of standard anion-exchange membranes limits the concentration of acid that can be achieved due to the free movement of protons (H+) from the high concentration acid stream through the anion membrane back to the diluting salt stream. The proton-blocking AR118U membrane limits this transfer and allows for higher concentrations in the acid and caustic streams, typically to 2.0N versus 1.0N with the AR103.

ED for Brine Concentration Membranes

Electrodialysis can be used as a brine concentrator for reaching concentrations higher than can be reached with reverse osmosis, thus reducing the size and energy consumption of thermal evaporators in ZLD applications. The Ionics CR62T membrane is designed, along with the AR103N, for use in these brine concentrations applications which require a low water transport membrane to achieve target concentrations of up to 200,000 mg/l TDS. Veolia continues to invest in innovation within our ion exchange membrane portfolio and in developing new applications using these membranes.

High pH Anion Membrane

Ionics AR908 membrane is a versatile anion exchange membrane that has been used by some of our largest EDR installations for drinking water and wastewater desalination. It allows for cleaning with high pH solutions which the AR204 does not. However, its resistance to chlorine is lower, so there can be a tradeoff depending on the specific application. The caustic resistance also makes it a cost-effective alternative to the AR103 membrane for process demineralization applications.


Membrane Innovations

Nonwoven Cloth Membranes

To improve performance of our ion exchange membranes, we discontinued use of a woven acrylic cloth and replaced it with a nonwoven polyester cloth. First, the nonwoven cloth membranes have lower electrical resistance. This means that when used, the voltage required to achieve a target product TDS can be lower. This can result in lower power consumption by the ED or EDR plant. Since the membranes are made of a nonwoven cloth, they will not generate “strings” hanging on the exterior of the stack as the edge of the membranes become dry, as happens with the use of woven cloths.

Here is an enhanced picture showing the texture comparison of the two membrane types: Woven acrylic cloth Nonwoven polyester cloth These membranes are NSF 61 certified as the woven acrylic cloth membranes were.

Nonwoven Polypropylene Membranes

Veolia will also convert the remaining membranes which use woven cloths to a nonwoven structure. AR103P and CR61P are cast on woven polypropylene cloth, and typically used in food and beverage applications. These membranes will be directly replaced by AR103N and CR61N. The ‘N’ type cloth is a thin nonwoven polypropylene cloth that will provide a superior membrane product with lower power consumption and smoother surface to reduce scaling and other deposits. Veolia will work with all current customers to ensure a smooth transition to the new membranes. 

Thinner Membranes

As part of our new generation of ED and EDR stack designs, the Ionics V Series, Veolia is producing thinner membranes that fit in our recessed spacer design to further improve electrical resistance for more efficient ED and EDR operation. These membranes can also be used in existing MkIV stack hardware to provide lower power consumption and/or expanded capacity. 750 cells of membranes will fit in the space that 600 cells of the thicker membranes occupy.


Fact Sheets

Membrane Selection Guide

Veolia’s ion exchange membranes are ion selective membranes comprised of cross-linked co-polymers of vinyl monomers and containing quaternary ammonium anion exchange groups or sulfonic acid cation exchange groups.

See the Ionics Ion Exchange Membranes Factsheet

Membrane Fact Sheets