PVDF/CA共混微滤膜的研制

Preparation of PVDF/CA blend microfiltration membrane

通过PVDF与CA共混来提高PVDF膜的亲水性，以纯水通量、膜的最大泡点压力、平均泡点压力等性能为指标，设计了九因素（共混比、固含量、溶剂种类、溶剂比、添加剂种类及含量、蒸发时间、凝胶浴温度、凝胶时间）四水平的正交试验表研究膜制备过程中各因素对PVDF／CA共混微滤膜性能的影响．实验结果表明：固含量是最主要的影响因素，其次是共混比、溶剂种类、添加剂含量、凝胶浴温度、凝胶时间、蒸发时间、添加剂种类和溶剂比．较佳的成膜条件为：PVDF／CA共混比4：1，固含量12％～14％，添加剂N-甲基-2-吡咯烷酮质量分数2％～3％，二甲基甲酰胺／正丁醇混合溶剂比7：1，蒸发时间30s，在20～30℃的自来水中凝胶50～70min，在此较优条件下可制备孔径为0．55～0．65μm，0．06MPa下的纯水通量27℃时为205．37～292．53mL／（cm^2·h）的PVDF／CA共混微滤膜．

Cellulose acetate（CA） were introduced to hydrophilize PVDF membrane by blending to improve the antifouling character of membrane. A orthogonal table with nine factors and four levels for the PVDF- CA system was designed to study the influences of the casting solution composition and gelation conditions on the performance of PVDF/CA blend microfiltration membrane. The results Show that the most important factor was the solid content, and then the factors were the blend ratio and the solvent species etc. The casting solution composition and gelation conditions for the system were optimized and a PVDF/CA blend membrane with high pure water flux [205.37～292.53 mL/（cm^2·h）] were prepared, and the experimental results show that the suitable casting solution composition and gelation conditions for the PVDF- CA system are as follows： the solid content is 12% ～14%, the additive content is 2% ～3%, the ratio of DMF/n - butanol is 7：1, the evaporation time is 30 second, and the gelation time is 50～70 min （under 20～30℃）.