Abstract
Chitosan membranes for ultrafiltration were prepared by casting acetic acid solutions of chitosan including an each amount of polyethylene glycol (PEG) as additives. Additives were eliminated by elution in hot water after the neutralization of membrane. The water flux of the membrane was measured and the membrane structure was observed by the scanning electron microscope. The membrane was found to consist of three layers ; the surface, the internal microporous layer and the opposite surface. With increasing the amount of PEG from 25 phr to 100 phr at the membrane preparation, the water flux increased largely more than 1000 folds, but there was only a 10% increase in the degree of hydration, H, of the membrane. The drastic change in the macroscopic membrane structure occured in the vicinity of H = 0.7, i.e., the micropores which penetrated throughout the membrane were formed in the region H>0.7. The molecular weight of PEG also affected the membrane structure and the water flux.
