Dynamic microstructure of graphene oxide membranes and the permeation flux
Dynamic microstructure of graphene oxide membranes and the permeation flux
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DOI：
10.1016/j.memsci.2017.12.018
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发表时间：
2018-03-01
影响因子：
9.5
通讯作者：
Li, Kang
中科院分区：
文献类型：
--
作者：
Chong, Jeng Yi;Wang, Bo;Li, Kang
据报道，氧化石墨烯（GO）膜是一种有前景的分离屏障，由于GO薄片之间的明确的层间空间，其可以保留小分子和多价盐。然而，虽然一些研究表明通过极其曲折的运输路径的快速液体运输，但也获得了矛盾的观察结果（例如低渗透通量）。本文揭示了GO膜的动态微观结构，它对膜的性能有重要影响。我们表明，通过不同方法和不同基材制备的所有GO膜在过滤过程中的透水性严重降低，这是由于其原始松散微观结构的压实。水通量可以在超过10小时后从数十LMH巴（-1）连续下降到< 0.1 LMH巴（-1）。这一结果表明，通过现有方法制备的GO膜的结构与理想的层状结构相差甚远。所观察到的GO膜的高渗透性可归因于无序的膜微结构。因此，假设GO膜中完美层状结构的传输机制和快速传输假设可能不能完全描述GO膜中的水传输。有趣的是，GO膜的松散堆积的微结构也被发现是可逆的，这取决于储存条件。
Graphene oxide (GO) membranes have been reported to be a promising separation barrier that can retain small molecules and multi-valent salts because of the well-defined interlayer space between GO flakes. However, while some studies suggested fast liquid transport through the extremely tortuous transport path, contradictory observations (e.g. low permeation flux) have also been obtained. This paper revealed the dynamic microstructure of GO membranes, which affected the membrane performance significantly. We showed that all GO membranes prepared by varied methods and on different substrates presented a severe reduction in water permeability during filtration, due to the compaction of their original loose microstructure. The water flux could drop continuously from tens of LMH bar(-1) to < 0.1 LMH bar(-1) after more than ten hours. This result demonstrated that the structure of GO membranes prepared by current approaches was far from the ideal laminar structure. The high permeability of GO membranes observed could be contributed by the disordered membrane microstructure. Therefore, the transport mechanisms assuming perfect laminar structure in GO membranes, and the fast transport hypothesis may not fully describe the water transport in GO membranes. Interestingly, the loosely packed microstructure of GO membranes was also found reversible depending on the storage conditions.