| In order to solve fundamentally the problem of membrane fouling in membrane separation process, the preparation and characteristics of anti-fouling ultrafiltration membranes were studied in this dissertation. Polymer blending to hydrophilized poly(vinylidene fluoride) (PVDF) ultrafiltration membrane was selected after reviewing a lot of literature, cellulose acetate (CA) was introduced as the second polymer due to its hydrophilicity. The compatibility of PVDF and CA were characterized by viscosity and DSC etc. Phase-inversion process was adopted to make membranes, and the effects of various preparative conditions on blend membrane were studied, and then the porosity, critical air bubble pressure, chemical stability, hydrophilicity and anti-fouling characteristics of the membrane were tested. It was indicated that the blend system of PVDF/CA is compatible in part, the hydrophilicity of PVDF was increased by blending with CA and thus the preformance of the membrane were improved. When the blend ratio of PVDF/CA=9/1, the content of polymer is 18%, the coefficient of resistance increment of alloy membrane is 0.43, decreasing 0.2 and 0.48 comparing with the pure PVDF membrane under the condition of the same permeation and the same process respectively. And also it was proved that the membrane characteristics were affected by blend ratio, type and content of additives and composition of precipitator. When PVDF/CA=9/1, polymer content is 15%, LiCI as the additive, the better membrane which has greater pure water permeation, higher rejection and better tenacity was obtained, whose pure water permeation is 49.5mL/cm2.h, the rejection of protein is more than 96%.
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