Abstract In this work, molecular dynamics simulations were employed to study the permeation of ethanol-water mixtures through single-layer graphene oxide (GO) nanopores functionalized with COOH (carboxyl) and COO- (ionized carboxyl) groups. GO-COOH nanopore shows regular behavior with competitive permeation between the two species in the mixture. However, GO-COO- pore exhibits selective permeation of water, suggesting COO- functionalized GO sheets could provide the initial barrier to block ethanol permeation and enhance dehydration separation in GO-based membranes. Our simulation presents the underlying mechanism of the selective water transport is not determined by the pore-size sieving, but has been ascribed as the strong molecular affinity between water and GO-COO- surface. This interfacial interaction can induce the preferential interfacial adsorption and pore occupation for water, simultaneously impede the transport path of ethanol into the nanopore, and consequently give rise to the selective penetration of water in the mixture. The simulation results provide the direct theoretical evidence that ionization of carboxyl groups on GO sheets can be applied to improve the dehydration permeation of alcohol-water mixtures across GO-based separation membranes.

中文翻译：

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功能化氧化石墨烯纳米孔的增强亲水性和水渗透性：分子动力学模拟

摘要 在这项工作中，分子动力学模拟被用来研究乙醇-水混合物通过用 COOH（羧基）和 COO-（离子化羧基）官能化的单层氧化石墨烯 (GO) 纳米孔的渗透。GO-COOH 纳米孔显示出规律的行为，混合物中两种物质之间存在竞争性渗透。然而，GO-COO-pore 表现出水的选择性渗透，表明 COO 功能化的 GO 片可以提供初始屏障以阻止乙醇渗透并增强基于 GO 的膜中的脱水分离。我们的模拟表明选择性水传输的潜在机制不是由孔径筛分决定的，而是归因于水和 GO-COO-表面之间的强分子亲和力。这种界面相互作用可以诱导水的优先界面吸附和孔隙占据，同时阻碍乙醇进入纳米孔的传输路径，从而导致水在混合物中的选择性渗透。模拟结果提供了直接的理论证据，即 GO 片上的羧基电离可用于改善醇 - 水混合物跨 GO 分离膜的脱水渗透。