| Several chitosan membranes w ith different molecular weight of 220,000, 350,000, 500,000, 680,000Da and different D.D (Degree of Deacetylation) of 90percent, 94percent 95percent, 97percent in molecular weight of 680,000Da were prepared. Their properties, such as crystal property, ultrastructure, mechanical property, swelling property;flux and rejection rating were studied. The results showed that the properties of the different membrane are correlative with the molecular weight of chitosan and D.D. Contrary to D.D, the membrane prepared of high D.D chitosan has little smoother surface than that of low D.D chitosan membranes. The rejection rating are inferior to that of low molecular weight membranes, but The flux are more excellent. Compare with molecular weight , influence of D.D are less evidence .The properties of chitosan membranes are considered to be dependent on their crystal property and ultrastructure.Chitosan ultrafiltrating compound membrane filled with activated carbon was prepared. The membrane cross-linked with C5H8O2 was used to treat water of printing and dyeing. The conditions of membrane preparation were analysed, including the number of activated carbon, the concentration of casting membrane solution, the number of cross-linking agent. The results showed that, under the experimental conditions, the new composite membrane are better than CS membrane in separation, decoloration efficiency and permeability.Ultrafiltration membrane is employed for employed for removal of COD, turbidity andcolor in the secondary effluent. The experimental results indicate that mean removal rate of COD is over 52%, the turbidity can be removal 100%, and the color removal rate is over 90%. Compare with membrane operation functions of vary work pressure, the best operation pressure is selected(AP=0.02MPa). The gel layer model which describe the removal of COD and the effective cleaning method for polluted membrane was presented.
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