自组装法制备PVDF-SiO_2/PVSQ超疏水复合膜及膜蒸馏抗污染性能

Fabrication of PVDF-SiO_2/PVSQ superhydrophobic compositemembrane via self-assembly with anti-fouling property for membrane distillation

采用乙烯基三甲氧基硅烷(VTMOS)对SiO_2疏水改性,通过自组装法,将改性SiO_2接枝在商业PVDF (聚偏氟乙烯)膜表面,使其表面达到超疏水。利用场发射电子显微镜、红外光谱仪、接触角测量仪及毛细流孔径分析仪等仪器对改性前后膜的表面形貌、化学组成、接触角及孔径变化等性能参数进行表征。结果表明,VTMOS不仅对SiO_2疏水改性,还通过自身的水解缩聚反应,生成了规整圆球状的聚乙烯基倍半硅氧烷(PVSQ)微粒,纳米级SiO_2分布于微米级PVSQ表面,在改性膜表面构造了多层次微/纳米粗糙表面,在低表面能疏水基团乙烯基和甲氧基的共同作用下,成功实现了超疏水改性,改性膜水接触角达到159.5°,滚动角降至8.1°。以NaCl、HA和CaCl2混合溶液为进料液,对商业PVDF膜和改性膜进行了长期直接接触式膜蒸馏(DCMD)实验,探究其抗污染性能。结果表明,改性膜适用于长期DCMD实验,并表现出比商业PVDF膜更稳定的通量,截盐率始终大于99.99%,具有良好的稳定性和抗污染性能。

The SiO2 was hydrophobically modified by vinyltrimethoxysilane(VTMOS),and the modified SiO2 was grafted onto the surface of commercial PVDF(polyvinylidene fluoride)membrane by self-assembly method to make the surface superhydrophobic.The VTMOS not only modified the SiO2 particles changing from hydrophilic into hydrophobicity,but also produced highly monodisperse spherical polyvinylsilsesquioxane(PVSQ)particles by selfhydrolysis and condensation reaction.The achievement of the superhydrophobic membrane surface was attributable to the hierarchical micro/nano rough structure constructed by the random distribution of SiO2 particles and spherical PVSQ particles,which together with the hydrophobic groups like vinyl groups and methoxyl groups which had low surface tension distributed on the coating surface.The results showed that the maximum water of contact angle modified membrane surface was up to 159.5°,and the sliding angle could reach 8.1°.The anti-fouling properties of the commercial and modified membrane were investigated by direct contact membrane distillation(DCMD)experiments with feed solution containing NaCl,HA and CaCl2.The results indicated that the modified membrane with superhydrophobic surface was suitable.