Abstract:

Using silica sol and dopamine as modifiers, SiO₂ modified layers were fabricated on the microporous polypropylene membrane (MPPM) surfaces by a one-step reaction. The resulted membranes were characterized with Fourier transform infrared spectroscopy (FTIR), environmental scanning electron microscopy (ESEM) and energy dispersive X-ray spectroscopy (EDX). The results confirmed that SiO₂ particle was dispersed uniformly on the MPPM surface. The experimental results of water/oil contact angle and water flux indicated that the modified membranes had superhydrophilic and underwater superoleophobicity surface, and showed excellent water permeability with high pure water flux [up to (5100±500) L·m^-2·h^-1 under 0.1 MPa]. The separation abilities of the modified membranes for oil/water emulsion were also investigated. It was found that the modified membranes could separate oil/water emulsion effectively with a highest water flux of 2830 L·m^-2·h^-1 and oil rejection ratio of 99.8% under 0.05 MPa. Moreover, oil rejection ratio of the modified membranes could retain above 99% even under 0.15 MPa, and the oil attached to the membrane surfaces could be easily removed by water. The silica-decorated membranes enable an efficient and energy-saving separation for oil/water emulsion, and thus shows attractive potential for practical oil/water emulsion separation.

Key words: membrane, surface, superhydrophilicity, silica, oil/water emulsion separation, polypropylene

摘要：

采用硅溶胶和多巴胺作为修饰剂,通过一步反应在微孔聚丙烯膜(MPPM)表面构建了SiO₂修饰层。利用FTIR、ESEM和EDX对膜进行了表征,发现膜表面SiO₂颗粒分布非常均匀。水/油接触角及纯水通量实验结果表明,修饰膜具有超亲水性及水下超疏油性,透水能力强,水通量大[在0.1 MPa时,水通量高达(5100±500)L·m^-2·h^-1]。油水乳液分离结果表明,修饰膜能有效分离油水乳液,在0.05 MPa时,油水乳液水通量达2830 L·m^-2·h^-1,油截留率达99.8%以上,即使过膜压力增大到0.15 MPa,油截留率也能保持在99%以上,且膜表面的油污可用水清洗除去,展现出很好的应用前景。

关键词: 膜, 表面, 超亲水性, 二氧化硅, 油水乳液分离, 聚丙烯