Schmuhl Riaan, Keizer Klaas, van den Berg Albert, ten Elshof Johan E, Blank Dave H A
Inorganic Materials Science, MESA+ Institute for Nanotechnology & Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands.
J Colloid Interface Sci. 2004 May 1;273(1):331-8. doi: 10.1016/j.jcis.2003.10.024.
The electric field-driven transport of ions through supported mesoporous gamma-alumina membranes was investigated. The influence of ion concentration, ion valency, pH, ionic strength, and electrolyte composition on transport behavior was determined. The permselectivity of the membrane was found to be highly dependent on the ionic strength. When the ionic strength was sufficiently low for electrical double-layer overlap to occur inside the pores, the membrane was found to be cation-permselective and the transport rate of cations could be tuned by variation of the potential difference over the membrane. The cation permselectivity is thought to be due to the adsorption of anions onto the pore walls, causing a net negative immobile surface charge density, and consequently, a positively charged mobile double layer. The transport mechanism of cations was interpreted in terms of a combination of Fick diffusion and ion migration. By variation of the potential difference over the membrane the transport of double-charged cations, Cu2+, could be controlled accurately, effectively resulting in on/off tunable transport. In the absence of double-layer overlap at high ionic strength, the membrane was found to be nonselective.
研究了电场驱动离子通过负载型介孔γ-氧化铝膜的传输过程。确定了离子浓度、离子价态、pH值、离子强度和电解质组成对传输行为的影响。发现膜的渗透选择性高度依赖于离子强度。当离子强度足够低以至于在孔内发生双电层重叠时，发现该膜具有阳离子渗透选择性，并且阳离子的传输速率可以通过改变膜上的电位差来调节。阳离子渗透选择性被认为是由于阴离子吸附在孔壁上，导致净负固定表面电荷密度，从而形成带正电的移动双电层。阳离子的传输机制用菲克扩散和离子迁移的组合来解释。通过改变膜上的电位差，可以精确控制双电荷阳离子Cu2+的传输，有效地实现开/关可调传输。在高离子强度下不存在双电层重叠时，发现该膜是非选择性的。
