凝胶相转化温度和空气预蒸发时间对PVDF超滤膜性能及结构的影响

EFFECTS OF PHASE CONVERSION TEMPERATURE AND EVAPORATION TIME ON THE PERFORMANCE AND STRUCTURE OF PVDF PLAT-MEMBRANE

利用非溶剂相转化法(NIPS),以聚偏氟乙烯(PVDF)/聚乙烯吡咯烷酮(PVP)/N,N-二甲基乙酰胺(DMAC)为铸膜液体系,水为凝固浴制备了大通量超滤膜。考察了铸膜液温度、凝胶浴温度、空气预蒸发时间等条件对超滤膜性能与结构的影响。研究结果显示,随着铸膜液和凝胶浴温度的提高,膜纯水通量增大,强度增强,截留率降低,膜的第一泡点压力减小,膜的孔隙率随铸膜液温度升高而增大,随凝胶浴温度升高先增大后减小,膜断面指状孔发育较为通透,海绵层致密。延长铸膜液在空气预蒸发时间,膜的第一泡点压力和孔隙率降低,超滤膜截留率提高,通量和强度变化不大。

Ultrafiltration plat-membranes of high pure water flux was prepared from PVDF/PVP/DMAC by anon-solvent induced phase separation（NIPS）method using water as coagulation bath.Effects of phase conversion temperature and evaporation time on the structure and performance of PVDF plat-membrane were investigated.The experimental results showed that,with increasing the temperature of membrane-casting solution and coagulation bath,the pure water flux and the strength of membrane improved but the retention and the first bubble point pressure decreases,porosities of membrane increases with increasing the temperature of membrane-casting solution and increases first and then decreases with coagulation bath temperature increased.The cross section with the big finger-like structure and the and compact sponge structure.Prolong the evaporation time the first bubble point pressure and porosity will be decreased,but the retention will be improved.However,the pure water flux and the strength of membrane had no obviously change.