关键词: 醋酸纤维素, 亲水性, 水通量, 截留率, 耐污染性

Abstract: Polyvinyl chloride (PVC) is one of the commonly used membrane materials, which has good acid-alkali resistance and mechanical properties. However, the film forming performance of PVC film is not very ideal at present, and the formed PVC film has strong hydrophobicity, low water flux, and poor toughness. Therefore, it is necessary to modify it to improve its hydrophilicity. Chlorinated polyvinyl chloride (CPVC) is obtained by deep chlorination of polyvinyl chloride, which has better mechanical properties and thermal stability than PVC materials. Cellulose acetate is an acetate of cellulose prepared by the reaction of cellulose with acetic anhydride mixture (or acetyl chloride). It has the advantages of good hydrophilicity and biocompatibility. Therefore, the blending modification of the three substances can improve the hydrophilicity and pollution resistance of the film, and provide a certain toughness.
PVC/CPVC/ cellulose acetate blends were prepared by phase transformation method. The shear viscosity, infrared spectrum, surface morphology, cross section morphology, pure water flux, retention rate and flux recovery rate of the blends were studied. The effect of the degree of esterification on the properties of the blended films was also studied. The results showed that the three materials had certain compatibility, and the separation film with good performance could be formed under a certain proportion of mixing. The comprehensive performance was the best when the PVC/CPVC/CA blending ratio was 70/10/20, and the water flux was 55.78 L/(m2 h) under 0.1MPa. For 0.1g/LBSA solution, the retention rate was 64.67%, the flux recovery rate was 55.92%, and the comprehensive performance was the best when the PVC/CPVC/CDA blend ratio was 65/10/25. At 0.1MPa, the water flux was 91.21 L/(m2 h). For 0.1g/LBSA solution, the retention rate was 90.85% and the flux recovery rate was 56.93%. The results showed that the hydrophilicity and anti-pollution properties of the membranes were significantly improved.
At present, there are few related studies on PVC blend film, and the study on PVC/CPVC/ cellulose acetate ternary blend has not been reported. In this paper, PVC/CPVC/ cellulose acetate blend film was prepared by phase transformation method. The film forming properties were analyzed and discussed by measuring the shear viscosity of the cast film liquid with different blending ratios. At the same time, the microstructure of the surface and cross section of the blend film were observed by field emission scanning electron microscopy (SEM). The hydrophilicity and separation performance of the membrane under different blending ratios were analyzed by water contact Angle, pure water flux and retention. On this basis, the influence of the degree of esterification of cellulose acetate on the properties of the membrane was analyzed, which provided a certain choice for the modified materials of PVC blend membrane and made it have a broader market prospect in sewage treatment.

Key words: cellulose acetate, hydrophilicity, water flux, retention, contamination resistance