Wu Yen-Yung, Lin Li-Chiang
Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan.
William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 W. Woodruff Avenue, Columbus, Ohio 43210, USA.
Phys Chem Chem Phys. 2024 Jul 24;26(29):19854-19862. doi: 10.1039/d4cp01830c.
Developing more energy-efficient and cost-effective membrane processes for the separation of ethanol and water represents a strategically important direction to facilitate the production of renewable biofuels. In this study, by employing state-of-the-art molecular simulations, the potential of zeolite nanosheets as reverse osmosis (RO) membranes in ethanol/water separation is investigated. These materials are predicted to offer unprecedentedly high fluxes and more importantly, the ethanol-to-water separation factor can be as large as approximately 800 if the structure is meticulously selected. The separation achieved herein can in fact be considered counter-intuitive as the membrane allows the larger ethanol molecules to permeate through while blocking smaller water molecules. Further investigations reveal that the observed selectivity is strongly correlated with the adsorption selectivity of the bulk materials, suggesting an adsorption-driven mechanism. Promising candidates also appear to have the largest cavity diameter of approximately 6 Å, a size that can be commensurate with the dimensions of ethanol to facilitate its adsorption. The hydrophilicity on the membrane surfaces is as well found to play a non-negligible role. Overall, this study demonstrates the great promise of zeolite nanosheets as RO membranes for extracting anhydrous ethanol from its aqueous mixture and provides guidance toward the selection of promising membrane candidates.
开发更节能、更具成本效益的用于分离乙醇和水的膜工艺是促进可再生生物燃料生产的一个具有战略重要性的方向。在本研究中，通过采用最先进的分子模拟，研究了沸石纳米片作为反渗透（RO）膜用于乙醇/水分离的潜力。预计这些材料能提供前所未有的高通量，更重要的是，如果精心选择结构，乙醇对水的分离因子可高达约800。本文实现的分离实际上可能被认为有悖常理，因为该膜允许较大的乙醇分子渗透，同时阻挡较小的水分子。进一步研究表明，观察到的选择性与块状材料的吸附选择性密切相关，这表明存在吸附驱动机制。有前景的候选材料似乎还具有约6 Å的最大腔直径，这个尺寸与乙醇的尺寸相当，便于其吸附。还发现膜表面的亲水性也起着不可忽视的作用。总体而言，本研究证明了沸石纳米片作为从其水混合物中提取无水乙醇的RO膜具有巨大潜力，并为选择有前景的膜候选材料提供了指导。
