EFFECTS OF IMMOBILIZED PECTINASE ON THE MICROFILTRATION OF DILUTE PECTIN SOLUTIONS BY MACROPOROUS TITANIA MEMBRANES - RESISTANCE MODEL INTERPRETATION

The retentive microfiltration of 1 g/dm(3) solutions of citrus and app le pectin was investigated at crossflow velocities up to 1.64 m/s usin g a tubular macroporous titania membrane 1.6 cm in diameter with an im mobilized pectinase. The flux was compared to the flux obtained using the same membrane without immobilized pectinase as a control membrane. The flux was significantly higher through the membrane with immobiliz ed pectinase than through the control membrane at the intermediate cro ssflow velocities, 0.80 and 1.2 m/s. Analysis of the flux results usin g a resistance model indicates that the resistance of the irreversible fouling layer was increased by the presence of immobilized pectinase at the intermediate crossflow velocities. However, the resistance asso ciated with concentration polarization, or resistance reversible to a water rinse, was reduced sufficiently under these crossflow conditions to increase the flux over that obtained with the control membrane. Mi nor differences in the Aux behavior were observed for the pectins from the two sources. The enzyme was active in reducing the molecular weig ht of the pectin in the permeate in all the experiments.