混合添加剂对PVDF平板疏水膜结构及性能的影响

Effect of mixed additives on structure and performance of PVDF flat sheet hydrophobic membrane

以不同添加剂采用浸没沉淀相转换法制备基于无纺布支撑的聚偏氟乙烯(PVDF)平板疏水膜,考察了不同添加剂的加入对膜性能与结构的影响;并利用扫描电子显微镜(SEM)、原子力学显微镜(AFM)、红外光谱(FTIR)、接触角测量及膜蒸馏实验等对疏水膜的结构及性能进行表征。结果表明,引入混合型添加剂制备的膜具有较高通量和盐截留率,其疏水性最强,而添加剂对聚合物的晶型影响较小。以35 g/L的NaCl盐溶液为进料液对制备的平板膜进行直接接触式膜蒸馏实验,在热侧进水温度为50℃、冷侧温度为20℃的条件下,所制备的疏水膜通量最高可达12.45 kg/(m2.h),截留率为99.99%。

The polyvinylidene fluoride（PVDF） flat hydrophobic membranes based on the support of non-woven fabric with different non-solvent additives were prepared by the immersion phase inversion process and the influence of different additives on structure and performances of flat hydrophobic membranes were investigated by scanning electron microscope（SEM）,atomic force microscope（AFM）,Fourier transform infrared spectroscopy（FTIR）,contact angle goniometer and membrane distillation experiment.The results showed that the membrane with acetone and phosphoric acid as the mixed additive exhibited high permeate and high rejection of inorganic salt,the additives had no obvious influence on the polymer crystallinity of hydrophobic membranes.Besides,the additives also increased the membrane surface roughness and enhanced the hydrophobicity.During the desalination process of 35 g/L sodium chloride solution through direct contact membrane distillation with the self-prepared membrane,a maximum permeate flux 12.45 kg/（m2·h） was obtained and the rejection of NaCl maintained 99.99% with the feed solution at 50℃ and the cold distillate water at 20℃.