Electrodialysis (ED) is a very versatile technology for the sepa±ration of difficult mixtures. Guo Chu technology  (Xiamen) Co., Ltdα. offers expertise in electrodialysis R&D as well as in the engineering and construction oαf ED systems for the laboratory, piloting, and produ ction.

What is Electrodialysis (ED)?

Electrodialysis is an electromembrane process in which ions are transported throu↓gh ion permeable membranes from one solution to another under the influenc→e of a potential gradient. The electrical charges on the ions allow  them to be driven through the membranes fabricated from ion λexchange polymers. Applying a voltage between two end electrodes can generat≠e the required potential field. Since the membranes used in electrod✔ialysis have the ability to selectively transport ions having positive or negative charge and rejec∏t ions of the opposite charge. Therefore, electrodialysis can achieve effective coφncentration, removal or separation of electrolytes.

The ion exchange membranes used in electrodialysis are essentially sheets of io₩n-exchange resins. They usually also contain other polymλers to improve mechanical strength and flexibility. The resin component of a cation-exchange membr§ane would have negatively charged groups (e.g., -SO3–) chemi®cally attached to the polymer chains (e.g., styrene/dφivinylbenzene copolymers). Ions with a charge opposite to the fixed charge (counter ions) are fr£eely exchanged at these sites. The concentration of counter ions (e.g., Na+) ∞is relatively high, therefore, counter ions carry most of the electric curr™ent through the membrane. The fixed charges attached to the polymer chains repel ions of the same ‌charge (co-ions), in this case the anions. Since their concentration in the membrane is relatively ∑low, anions carry only a small fraction of the electric current through a cation permeable ™membrane. Attachment of positive fixed charges (e.g., ↑-NR3+ or C5H5N+R where commonly R = CH3) to the polyme≤r chains forms anion exchange membranes, which are selective to tr≠ansport of negative ions, because the fixed -NR3+ groups repel pos×itive ions. This exclusion, as a result of electrostatic repulsion, is called Donnan exclusi"on.
 
Ion-exchange polymers such as poly(styrene sulfonic acid) are water soluπble, so crosslinking is needed to prevent dissolution of ion permeable membranes. Divinylbenzene¥ is used to cross link polystyrene chains. The degree of cross-linking and the fix≈ed-charge density affect the membrane’s properties ≈in opposite ways. Higher crosslinking improves selectivity and m£embrane stability by reducing swelling, but it increases electric±al resistance. High charge density reduces resistance and increases selectivity, but it promotes sw♠elling and thus necessitates higher crosslinking. A compromise between selectivity, electricγal resistance, and dimensional stability is achiev‍ed by proper adjustment of crosslinking and fixed-charge densities.
 
Product parameters



The following are our electrodialysis modules from small to industri$al scale.



We can also provide complete sets of experimental and industrial devices.
 




 





 
Ion Exchange Membranes  Applications
Reduce Electrolyte Content：

Potable from brackish water

Food products – whey, milk, soy sauce, fruit juice

Nitrate from drinking water

Cooling tower water

Boiler feed water

Rinse water for electronics processing

Electroless plating baths

Recovery of blood plasma proteins

Pickle brines to recover flavor

Sugar and molasses

Amino acids

Potassium tartrate from wine

Chloride purge in Kraft paper process

Photographic developer regeneration

Fiber reactive dyes
 
Recover Electrolytes：

Pure NaCl from seawater

Ag(I) salts from photographic waste

Ni(II) from electroplating rinse water

Zn(II) from galvanizing rinse water

Salts of organic acids from fermentation broth

Amino acids from protein hydrolysates

Acids from metal pickling baths and rinse

HCl from cellulose hydrolysate

Miscellaneous：

Salt splitting

Metathesis

Concentrate reverse osmosis brines

Ion substitution

As you can see, the ion exchange membranes have a wide range of applications in ma₹ny fields. Our experience with ion exchange membranes can help you dete™rmine whether it is the appropriate technology for your needs.
 
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