Molecular Filtration by Ultrathin and Highly Porous Silica Nanochannel Membranes: Permeability and Selectivity
Molecular Filtration by Ultrathin and Highly Porous Silica Nanochannel Membranes: Permeability and Selectivity
复制标题
超薄高孔二氧化硅纳米通道膜的分子过滤：渗透性和选择性
DOI：
10.1021/acs.analchem.6b02968
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发表时间：
2016
影响因子：
7.4
通讯作者：
Su Bin
中科院分区：
文献类型：
--
作者：
Yang Qian;Lin Xingyu;Su Bin
理想的分子过滤膜应该是高渗透性和选择性的，因此期望膜是可渗透的，是高度多孔的，并且由小且均匀的孔或通道组成。在这项工作中，我们报告的分子过滤的独立的二氧化硅纳米通道膜（SNMs），使用U形细胞和分光光度检测，侧重于定量评价的渗透性和选择性的SNMs。由于超小的通道尺寸，即，102 -3 nm，和负电荷的通道表面所产生的硅烷醇基团的去质子化，SNM显示出优异的尺寸和电荷选择性的分子过滤。由于孔道大小均匀，小分子甲基紫精与大分子细胞色素的分离选择系数高达273。基于电荷的过滤可以通过盐浓度和溶液pH来调节，盐浓度和溶液pH分别控制径向双电层和表面电荷符号/密度的重叠。由于高的相对孔密度，即16.7%，和直的和垂直的通道取向，SNM是高度可渗透的，显示出比市售的透析膜和其他先前报道的高得多的分子通量。此外，我们证明，通过偏置一个小的电压在SNM，通量和分离选择性可以显着提高。
An ideal molecular filtration membranes should be highly permeable and selective, thus desiring the membranes to be ultrathin, be highly porous, and consists of small and uniform pores or channels. In this work, we report the molecular filtration by free-standing ultrathin silica nanochannel membranes (SNMs) using a U-shaped cell and spectrophotometric detection, focusing on the quantitative evaluation of permeability and selectivity of SNMs. Thanks to the ultrasmall channel size, namely, ∼2–3 nm, and the negatively charged channel surface arising from the deprotonation of silanol groups, the SNM displayed excellent size and charge selectivity for molecular filtration. The selectivity coefficient for separation of small methyl viologen from large cytochromecis as high as 273, because of the uniform pore/channel size. The charge-based filtration can be modulated by the salt concentration and solution pH, which control the overlap of radial electrical double layer and surface charge sign/density, respectively. Owing to the high relative pore density, namely, 16.7%, and the straight and vertical channel orientation, the SNM is highly permeable, displaying a molecule flux much higher than commercially available dialysis membrane and others reported previously. In addition, we demonstrated that, by biasing a small voltage across the SNM, both the flux and separation selectivity could be significantly enhanced.