Bush Stevie N, Ken Jay S, Martin Charles R
Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States.
ACS Nano. 2022 May 24;16(5):8338-8346. doi: 10.1021/acsnano.2c02597. Epub 2022 Apr 29.
There is increasing interest in understanding the properties of solutions confined within nanotubes and synthetic or biological nanopores. How the ionic content of a nanopore-confined solution differs from that of a contacting bulk salt solution is of particular importance, for example, to water desalinization, industrial electrolysis, and all living systems. This paper explores ionic content, ionic interactions, and ion-transport properties of solutions confined within the 10 nm diameter pores of a synthetic polymer membrane. The membrane has a fixed negative pore-wall and surface charge due to ionizable carbonate groups. As a result, under some conditions, the nanopore-confined solution contains only cations and no anions or salt present in a contacting solution, ideal cation permselectivity. This anion- and salt-rejecting ability varies greatly with the cation of the salt, a result that is in contradiction to the prevailing model for permselectivity in nanopores. The extant model fails because it does not account for specific chemical interactions between the cation and the carbonate groups. The nature of these ion-selective interactions is discussed here.
人们对理解限制在纳米管以及合成或生物纳米孔内的溶液性质的兴趣与日俱增。例如，对于水脱盐、工业电解以及所有生命系统而言，纳米孔限制溶液的离子含量与接触的本体盐溶液的离子含量有何不同尤为重要。本文探讨了限制在合成聚合物膜直径为10 nm的孔内的溶液的离子含量、离子相互作用和离子传输性质。该膜由于可电离的碳酸酯基团而具有固定的负孔壁和表面电荷。因此，在某些条件下，纳米孔限制溶液仅包含阳离子，而接触溶液中不存在阴离子或盐，即理想的阳离子选择透过性。这种排斥阴离子和盐的能力随盐中的阳离子而有很大变化，这一结果与纳米孔中选择透过性的主流模型相矛盾。现有的模型不成立，因为它没有考虑阳离子与碳酸酯基团之间的特定化学相互作用。本文讨论了这些离子选择性相互作用的性质。
