Electrodialysis with bipolar membranes applications

Electrodialysis with bipolar membranes (EDBMs) [23] was applied recently to the production of mineral and organic acids [24-36], inhibition of enzymatic browning [37-39], and separation of protein [40-44]. These applications are based on water dissociation at the interface of a bipolar membrane (BPM) coupled with monopolar membrane action. A recent up-to-date overview gives the possibilities and the economic relevance of BPM technology [45]. 

H.P. Rapp, G. Eigenberger and H. Strathmann, Electrodialysis with bipolar membranes - theory and application , Proc. of ICOM 96 The 1996 International Congress on Membranes and Membrane Processes), Yokohama, Aug. 18-23, p. 506-507. 

Application of conventional electrodialysis and electrodialysis with bipolar membranes in the development of new processes desalination of wastewater from organic synthesis processes to allow recovery and reuse in the system obtention of high value products that can increase their pharmacological activity by substitution of the anions or cations present in natural sources. 

Pourcelly G, Gavach C (2000) Electrodialysis water splitting - application of electrodialysis with bipolar membranes. In Kemperman AJB (ed) Handbook of bipolar membrane technology. Twenty University Press, Enschede... 

Electrodialysis is by far the largest use of ion exchange membranes, principally to desalt brackish water or (in Japan) to produce concentrated brine. These two processes are both well established, and major technical innovations that will change the competitive position of the industry do not appear likely. Some new applications of electrodialysis exist in the treatment of industrial process streams, food processing and wastewater treatment systems but the total market is small. Long-term major applications for ion exchange membranes may be in the nonseparation areas such as fuel cells, electrochemical reactions and production of acids and alkalis with bipolar membranes. 

The future for electrodialysis-based wastewater treatment processes appears bright. The dilute concentrations of metals in the waste streams do not degrade or foul the cation or anion exchange membranes. The concentrate streams are recirculated to build up their metal content to a level that is useful for further recovery or direct return to the process stream. Ongoing research in the development of cheaper cation exchange membranes, and stable anion exchange and bipolar membranes will allow electrodialysis-based applications to become more competitive with other treatments. 

The practical use of bipolar membranes for the recovery of acids and bases from the corresponding salts by electrodialytic water dissociation in the early 80 s by Liu et al. [9] opened a multitude of new applications in chentical industry and in waste water treatment. The combination of electrodialysis with conventional ion-exchange technology and the use of conducting spacers are both commercially and technically very interesting variations of the basic process [10]. 

Electrodialysis was developed first for the desalination of saline solutions, particularly brackish water. The production of potable water is still currently the most important industrial application of electrodialysis. But other applications, such as the treatment of industrial effluents [45], the production of boiler feed water, demineralization of whey [46], de-acidification of fruit juices [47], etc. are gaining increasing importance with large-scale industrial installations. An application of electrodialysis which is limited regionally to Japan has gained considerable commercial importance. This is the production of table salt from sea water. Diffusion dialysis and the use of bipolar membranes have significantly expanded the application of electrodialysis in recent years [48]. 

The use of bipolar membranes with the conventional cation and/or anion exchange membranes allows very interesting applications to develop, different from the dilution or concentration of solutions characteristic of cmiventional electrodialysis. ... 

Proteins can be preferentially precipitated from solution using a technique known as electrodialysis coupled with the use of bipolar manbranes. The application is based on the specific properties of electrolysis (redox reactions at the electrodes) coupled with membrane action (Bazinet et al, 1998) resulting in either electro-acidificalion or electro-alkalinization. A bipolar membrane is a composite membrane consisting of a cation exchange layer and an anion exchange layer which can spUt solvents (water and methanol, so far) into H and OH7 CHjO at the interface under reverse potential bias (Xu and Huang, 2008). 

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