DOI: 10.5176/2301-3761_CCECP18.6
Authors: Zeyu Zhao, Xian Kong and Jianwen Jiang
Abstract:
Organic solvents are intensively used in chemical industry, and the separation and recovery of solvents accounts for a significant portion of energy consumption and capital cost in many chemical processes. Switching solvent recovery process from traditional distillation to membrane nanofiltration could reduce the energy cost and carbon emission to a large extent. In this study, molecular dynamics simulations have been conducted to investigate the permeation process of two organic solvents (methanol and ethanol) via three zeolitic imidazolate framework (ZIF) membranes, namely ZIF-25, -71 and -96. These ZIFs have a RHO topology with windows of around 5 Å and cages of around 17 Å. Both solvents show good flux via the ZIF membranes. In all three ZIF membranes, methanol permeates faster than ethanol due to a smaller molecule size and a lower viscosity. The chemical properties of the inner membrane surface plays an important role in the permeation process. ZIF-25 membrane exhibits the highest flux and permeability for both solvents due to its hydrophobic nature, despite it’s the smallest window size among the three ZIFs; whereas ZIF-96 membrane shows the lowest flux due the strong interaction between its highly hydrophilic surface and solvent. This molecular simulation study provides microscopic insights into the permeation behavior of solvent molecules in the ZIF membranes, suggests that ZIFs are potential materials for organic solvent recovery.
Keywords : molecular simulation; organic solvent nanofiltration (OSN); zeolitic imidazolate framework (ZIF)
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