Electrodialysis Membranes
Electrodialysis membrane layers are critical components in the electrodialysis process. The electrodialysis principle uses electricity and selectively permeable membranes to remove anions and cations from water and other feed solutions.
In almost all practical electrodialysis processes, multiple electrodialysis cells are arranged into a configuration called an electrodialysis stack or module, with alternating anion and cation exchange membranes forming the electrodialysis cells.
Electrodialysis Membranes Working Principle
The working principle of electrodialysis ion-exchange membranes involves the selective passage of ions: cation-exchange membranes allow positively charged ions (cations) to pass through, while anion-exchange membranes allow negatively charged ions (anions) to pass through, effectively removing them from the feed stream.
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Under the brand DESALT we currently supply both types of electrodialysis Ion-Exchange Membranes: Cation-Exchange Membranes (CEMs) and Anion-Exchange Membranes (AEMs). Depending on the charge, these membranes allow for negatively charged ions (anions) to pass through while positively charged ions (cations) or vice versa.
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In the picture below we represent the working principle of ion-exchange membranes used for electrodialysis:
DESALT Electrodialysis Membrane Technology: Improving Treatment Processes
As industries in water and wastewater treatment seek to optimize their operations, one critical aspect they often focus on is the efficiency of their electrodialysis membrane separation efficiency.
Whether it is to purify water, recover valuable materials, or remove pollutants, DESALT electrodialysis membranes play a vital role in many industrial sectors.
Electrodialysis Membrane Stack and Modules Working Principle
Electrodialysis is a type of membrane-based separation technology that uses electric fields to move ions across membranes. Essentially, electrodialysis works by selectively removing charged particles from a feed stream and concentrating them into a separate stream. This separation is achieved by placing alternating cation- and anion-exchange membranes arranged in repeating units between two electrodes.
By applying an electric potential across the electrodes, ions in the feed stream are driven towards the opposite charge membrane, where they can pass through and be trapped by an adjacent membrane of the same charge. This process creates a series of compartments or "cells" within the electrodialysis membrane stack, each containing a specific ion concentration.
In the picture above we show the typical configuration of an electrodialysis membrane stack. The electrodialysis process utilizes an electrodialysis stack built on the filter press principle. A typical ED membrane stack consists of 100–400 alternate cationic and anionic membranes between two electrodes; the aqueous feed solution flows through the cells between each pair of membranes. Because of the arrangement of ion-selective membranes, the migrating ions become concentrated in each alternate cell in the stack. Thus, ions removed from the aqueous feed solution are concentrated into two separate streams.
Applications for Electrodialysis Membranes
Electrodialysis membranes are currently use for various applications, including:
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Removal of salts from feed liquids in various production processes such as chemical/food/pharmaceuticals;
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Preparation, treatment and recycling of industrial water such as industrial primary pure water, industrial reclaimed water, industrial salt-containing wastewater, and reverse osmosis brine;
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Preparation of domestic and drinking water such as surface water purification, brackish water desalination and seawater desalination.