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NEOSEPTA BIPOLAR

Ion exchange membrane featured by, for example, low voltage electrolysis of water, electrolysis without oxidation-reduction reaction, space saving and reduced initial investment. It is applicable to generate organic substance fro its organic salt, splitting of organic substance to acid and alkali in one step processing.

PRINCIPLE

The Bipolar Membrane is an Ion Exchange Membrane having a structure combining an Anion Exchange layer and a Cation Exchange layer.
Applying Bipolar Membrane with DC current to give a theoretical water dissociation voltage of 0.83V produces a rectification phenomenon, making it possible to dissociate water into H⁺ and OH^-. (Fig.6)

Fig.6 Bipolar Membrane

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When a Bipolar Membrane, Anion Exchange Membrane and Cation Exchange Membrane are installed in the Electrodialyzer and a solution is fed as shown Fig.7, ions move as indicated by arrows and H₂SO₄ and NaOH are generated from Na₂SO₄. The reaction formula is as shown below.
Na₂SO₄ + 2H₂O -> 2NaOH + H₂SO₄

Fig.7 Bipolar Membrane Electrodialysis

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FEATURE

1	Since water is dissociated into hydrogen ions and hydroxide ions, no gas is generated and a low dissociation voltage can be applied.
2	No electrode reaction takes place on Bipolar Membrane, and therefore no oxidation or reduction reaction takes place, either. For this reason, there is no possibility which unexpected products will be produced.
3	Combining a Bipolar Membrane with an Anion Exchange Membrane and Cation Exchange Membrane makes it possible to convert salt such as Na₂SO₄, NaCl and NaNO₃,etc. to acid and alkali.
4	There is no need to provide an Electrode for each pair, which contributes to a reduction of installation space and reduction of initial cost.
5	It is possible to convert organic salt to organic acid and alkali through a single process.
6	It is possible to minimize generation of waste.
7	It is possible to recycle salts of intermediates by converting to acid and alkali.

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Specifications of the Bipolar Membrane "NEOSEPTA BP-1E"
Water splitting voltage^*1	1.2V^*2
Water splitting efficiency^*1	0.98
Burst strength	0.40MPa
Maximum effective sheet size	1m x 1m
Thickness	0.22mm
*1 : Measured between 1N NaOH and 1N HCl, 10A/dm² 30ºC
*2 : Potential drop across the "NEOSEPTA BP-1E" of platinum wire set away 5mm from bipolar membrane surface.
*3 : Above specifications of "NEOSEPTA BP-1E" are based on tests that we believe reliable,but not guaranteed values.

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Models

ACILYZER 02B

ACILYZER 10B

ACILYZER 25B

ACILYZER 50B

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APPLICATION EXAMPLE

Organic Acid Production

When organic acid is produced at fermentation process starting from starch and molasses, the conventional method needs to neutralize the organic acid by adding soda-lime which produces calcium salt of organic acid. Problem is that this method generates large volume of gypsum as a by-product.
The organic acid production process by Bipolar Membrane method can concentrate organic salt produced at fermentation method through Electrodialysis and convert it to organic acid by Bipolar Membrane Electrodialysis. (Fig.8)
This method is simple and easy processes and requires low running cost which constitutes outstanding features of this method.

Fig.8 Flow Chart of Organic Acid Production