Electrospun nanofiber membrane for membrane adsorption, membrane contactor and fouling mitigation in ultrafiltration

纳米材料可以被合理地设计来展示出新颖和显著的改进 物理和化学性质。聚合物纳米纤维是一类重要的纳米材料，在过去的十年里引起了越来越多的关注。 特别是，电纺纳米纤维膜(ENM)已被证明适用于实验室规模的各种膜处理工艺，如中频、超滤、纳滤、MD、FO、PRO、膜吸收和膜吹脱。拟议的项目旨在进一步扩大ENMS作为水和气体处理滤膜的适用范围。ENMS的水处理现在正处于商业化的边缘。有一些公司正致力于水处理用纳米纤维膜的商业化(例如，2010年在美国北卡罗来纳州成立的Xanofi)。拟议的项目将通过展示生态系统的各种新应用，促进生态系统的未来商业化。 因此，这项研究的目标是： 1)制备并测试了用于膜吸附去除水中砷的电纺纳米纤维膜(以下简称混合基质纳米纤维膜)。 2)在膜接触器(MC)中制作和测试用于从二氧化碳/氮气混合气体中捕集二氧化碳的ENMS 3)制备平行排列的ENM，用于在超滤应用中减轻污染和增强洗涤 在过去的几十年里，天然水中的砷污染因其高毒性、在人体内的积累和致癌性而引起了人们对环境和公共卫生的极大关注。近年来，亲和膜的发展为低压除砷提供了一种有效的方法。考虑到非常高的孔隙率和互连性，ENM在MA中使用时预计会有更高的通量。 膜接触器(MC)是气体和液体在多孔膜的两侧流动，气体成分通过膜孔从气体扩散到液体，气体被液体中的吸收剂吸收的过程。它的应用之一是从天然气和烟道气中去除二氧化碳。膜接触器的单位体积接触面积是常规分离柱的4~30倍。ENM具有较高的孔隙率和疏水性，是制备MC膜的理想候选材料。 最近在金属氧化物复合聚合物膜的开发过程中观察到，聚合物结节平行排列，原子力显微镜(AFM)在膜表面观察到非常清晰的图案。 研究还发现，当进料方向与图案线垂直时，膜污染可以大大减少，而当进料方向与图案线平行时，膜清洗是有效的。纳米纤维在ENM中的平行排列将在膜表面提供完美的图案，从而增强上述效果。

Nano-scale materials can be rationally designed to exhibit novel and significantly improved physical and chemical properties. Polymer nanofibers, an important class of nano-materials, have attracted increasing attention during the past decade. In particular, electro-spun nanofiber membranes (ENMs) have already been proven to be applicable in a variety of membrane processes for water treatment, such as MF, UF, NF, MD, FO, PRO, membrane absorption and membrane air stripping in the laboratory scale. The proposed project aims to widen the scope of the applicability of ENMs as filtration membrane for water and gas treatment even further. Water treatment by ENMs is now on the verge of commercialization. There are companies who are aiming at the commercialization of nanofiber membranes for water treatment (e.g. Xanofi, founded in 2010 in NC, USA). The proposed project will contribute to the future commercialization of ENMs by demonstrating a variety of novel applications of ENMs. Thus, the objectives of this research are: 1) To fabricate and test the metal oxide nanoparticles incorporated electro-spun nanofiber membranes (ENMs) (hereafter called Mixed Matrix ENMs (MMENMs)) for the removal of arsenics from water by membrane adsorption (MA) 2) To fabricate and test ENMs in membrane contactor (MC) application for capturing CO2 from CO2/N2 gas mixtures 3) To fabricate ENMs aligned parallel for fouling mitigation and washing enhancement in ultrafiltration applications In the last few decades, arsenic contamination in natural water has raised significant environmental and public health concerns because of its high toxicity, accumulation in human body and carcinogenicity. Recently, the development of affinity membrane provided an effective method for arsenic removal under low pressure. In view of very high porosity and interconnectivity, a much higher flux is expected by ENMs when they are used in MA. Membrane contactor (MC) is a process in which gas and liquid flow on the opposite sides of a porous membrane; a gaseous component diffuses through the membrane pore from the gas to liquid phase where the gas is absorbed by the absorbent in the liquid. One of its applications is CO2 removal from natural and flue gas. Membrane contactor can provide contact area per unit volume 4 to 30 times higher than the conventional separation columns. ENM is an excellent candidate for membranes for MC for its high porosity and hydrophobicity. An observation was made recently during the development of metal oxide incorporated polymeric membranes; i.e. polymer nodules were aligned parallel, and very clear patterns were observed by the Atomic Force Microscopy (AFM) at the membrane surface. It was also found that the membrane fouling could be reduced substantially when the feed flow was oriented perpendicular to the patterned lines, while membrane washing was effective when the feed flow was oriented parallel to the patterned lines. Parallel alignment of nanofibers in ENM will provide a perfect pattern at the membrane surface and thus enhance the above effects.