Abstract
AbstractThe effects of membrane structure on the separation of L‐phenylalanine (L‐Phe) by electrodialysis from a fermentation broth and on the fouling tendency were investigated in this study. Two anion‐exchange membranes (Neosepta AFX and AM‐1, Tokuyama, Japan) were selected and characterized using the chronopotentiometry method. For a fresh membrane, AFX showed a lower electrical resistance and a lower permselectivity than AM‐1. After being fouled with humic acid, however, the electrical resistance of AFX was higher than that of AM‐1. The L‐Phe selectivities for both membranes were lower than those of the fresh membranes. The result may be attributed to the structural difference between AFX and AM‐1 membranes. AFX has a lower repulsion force against the co‐ion and could be more strongly affected by the foulants than AM‐1 because AFX has a more porous structure than AM‐1. Experiments on the separation of L‐Phe from the fermentation broth were carried out using two different stack configurations, ie desalting electrodialysis and water‐splitting electrodialysis. It was observed that the recovery efficiency of L‐Phe through electrodialysis for 100 min reached 95% for AFX and 85% for AM‐1. In the desalting configuration of electrodialysis, the solution pH must be adjusted to alkaline conditions to recover the L‐Phe through the anion‐exchange membrane. On the contrary, it was possible to recover the L‐Phe without adjustment of the solution pH in the water‐splitting electrodialysis because OH− generated from the bipolar membrane converted neutral L‐Phe into an anion.© 2002 Society of Chemical Industry
Published Version
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