Abstract Dual functional membranes with super-wetting and adsorption capacity have drawn great attentions owing to their good application prospect in the treatment of mixed wastewater containing oil and dyes. Despite recent development in such functional membranes, there are still some obstacles need to be resolved. The one is how to further improve the dye adsorption capacity to realize the high-efficiency removal of dye under high permeation flux. The other is to improve the rejection towards nano-sized oil droplets in water. Herein, with porous polypropylene (PP) membrane as substrate, we show that constructing multiple hierarchical structures (MHS) on membrane surface is an effective way to solve the above mentioned problems. The MHS prepared by low-cost tannic acid, 3-Aminopropyltriethoxysilane (APTES), and polyethyleneimine (PEI) are composed of rough layer, nanospheres, and nano nodes with abundant amine groups. On the one hand, the MHS can endow the membrane with high adsorptive capacity (480 mg g−1 toward methyl blue). On the other hand, the MHS can also decrease the pore size of the membrane, making it suitable for separation of nano-sized oil droplets. Moreover, the MHS can also render the membrane superhydrophilicity and excellent anti-oil-adhesion properties. Thanks to these advantages derived from MHS, the obtained dual functional membrane can realize high-efficiency and simultaneous removal of high concentrated dye (10–50 ppm, removal efficiency>95%) and nano-sized oil droplets (about 50–300 nm, oil rejection>99%) from mixed wastewater under high flux (1680 L m−2 h−1). Considering the significantly enhanced performance, as well as the facile and cost-effective process, the as-prepared functional membrane with MHS has good application prospects. Besides, a new insight on the influence of hydrodynamic conditions on membrane fouling during emulsion separation is also proposed, which may guide better design of anti-fouling membranes.

中文翻译：

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具有多重层次结构 (MHS) 的双功能膜，可在高通量下同时高效去除水中的染料和纳米油滴

摘要 具有超润湿和吸附能力的双功能膜因其在处理含油染料混合废水方面具有良好的应用前景而备受关注。尽管最近在此类功能膜方面取得了进展，但仍有一些障碍需要解决。一是如何进一步提高染料吸附能力，实现高渗透通量下染料的高效去除。另一个是改善对水中纳米级油滴的排斥。在此，以多孔聚丙烯（PP）膜为基材，我们表明在膜表面构建多层结构（MHS）是解决上述问题的有效途径。由低成本单宁酸、3-氨基丙基三乙氧基硅烷（APTES）制备的MHS，聚乙烯亚胺（PEI）由粗糙层、纳米球和具有丰富胺基的纳米节点组成。一方面，MHS 可以赋予膜高吸附能力（480 mg g-1 对甲基蓝）。另一方面，MHS 还可以减小膜的孔径，使其适用于纳米级油滴的分离。此外，MHS还可以赋予膜超亲水性和优异的抗油粘附性能。得益于MHS的这些优点，所获得的双功能膜可以实现高效同时去除高浓度染料（10-50 ppm，去除效率> 95%）和纳米级油滴（约50-300 nm，在高通量 (1680 L m-2 h-1) 下从混合废水中脱油 >99%）。考虑到显着增强的性能，所制备的含MHS功能膜不仅工艺简便、成本低廉，而且具有良好的应用前景。此外，还提出了关于乳液分离过程中水动力条件对膜污染影响的新见解，这可能有助于更好地设计防污膜。