THE EFFECT OF SUBSTRATE MASS TRANSFER LIMITATIONS IN AN IMMOBILIZED ENZYME MEMBRANE REACTOR

An unstirred ultrafiltration cell can be quite easily converted into an immobilized enzyme reactor. Indeed, if suitable amounts ofproteic solutions are fed and if the protein molecular weight exceeds the membrane cut off, gel precipitation occurs onto the active surface of the membrane because of concentration polarization phenomena. Two different gel formation procedures have been followed. Indeed, two different proteic solution have been injected, namely

1.a mixture of an inert protein and the enzyme

2.co-polymer obtained by co-cross-linking the enzyme and the inert protein.

Substrate mass transfer limitations which occur in the gel immobilized enzyme reactor have been considered. The relevance of mass transfer resistances upstream from the immobilized gel layer has been discussed together with the intrinsic enzyme kinetics.

A heterogeneous gel model has been proposed which adequately describes the experimental results. Effectiveness factor correlations of fairly general applicability have been also presented.