(369b) Molecular Insight into Seawater Pervaporation through Zeolitic Imidazolate Framework Membranes
AIChE Annual Meeting
2016
2016 AIChE Annual Meeting
Separations Division
Molecular Simulation of Adsorption II
Tuesday, November 15, 2016 - 12:50pm to 1:10pm
In this study, an atomistic simulation study is reported for seawater pervaporation through five zeolitic imidazolate framework (ZIF) membranes including ZIF-8, -93, -95, -97 and -100. Salt rejection in the five ZIFs is predicted to be 100% due to the sieving of small apertures. The hierarchy of water flux is as ZIF-100 >> -8 > -95 > -93 > -97. With the largest aperture, ZIF-100 possesses the highest water permeability of 5 ´ 10-4 kg×m/(m2×hr×bar), which is substantially higher compared to commercial reverse osmosis membranes, as well as zeolite and graphene oxide pervaporation membranes. In ZIF-8, -93, -95 and -97 with similar aperture size, water flux is governed by framework hydrophobicity/hydrophilicity; in hydrophobic ZIF-8 and -95, water flux is higher than in hydrophilic ZIF-93 and -97. Furthermore, water molecules in ZIF-93 move slowly and remain in the membrane for a long time, but undergo to-and-fro motion in ZIF-100. The lifetime of hydrogen bonds in ZIF-93 is found to be longer than in ZIF-100. This simulation study quantitatively elucidates the dynamic and structural properties of water in ZIFs, identifies the key governing factors and suggests ZIF-100 is an intriguing membrane for seawater pervaporation.