| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2004: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2003: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2002: ¥2,700,000 (Direct Cost: ¥2,700,000)
|
|---|
| Research Abstract |
We have developed a new technique of electrodialysis with a bipolar membrane and ion-exchange membranes. The technique has a separating zone with pH steps between compartments, and may be possible to separate ampholytes by difference of the isoelectric points. The electrodialyzer composed of six compartments, which were divided by a cation-exchange membrane, a bipolar membrane, and anion-exchange membranes, respectively. When a voltage was applied to the electrodialyzer, hydroxide ions were electrically generated by the anion-exchange layer in the bipolar membrane, and moved to anode side compartments through anion-exchange membranes. The hydroxide concentration in each compartment was almost equall to the concentration of coexisting cations, and formed alkaline-pH steps in the electrodialyzer. Moreover, we attempted to apply the bipolar membrane technique to separation of acidic and neutral amino acids. In the range of pH steps of 8 to 13, acidic amino acid permeated through the anion-exchange membranes, and accumulated in the anode compartment, although neutral amino acids remained in the feed compartment. Thus, the separation by the new technique proceeded well. All the experimental data were simulated by a mathematical model, which considers dissociation of amino acids, electro-neutrality in the solution, ion-exchange equilibrium, hydroxide production rate with a bipolar membrane, and flux in the anion-exchange membranes. The model well explained the experimental results of the formation of pH steps in the electrodialyzer, and of the amino acids separation.
|
