Synergistic Preparation of Stable Al-Fum Based Tubular Membrane for Pervaporation Separation of Water–Ethanol–Ethyl Acetate Azeotropic Mixtures
Purification and dehydration of ethyl acetate are important processes in chemical production, and the preparation of stable and efficient pervaporation membrane materials has still been a challenge. In this work, a well-intergrown polycrystalline Al-Fum@CS tubular membrane was successfully prepared by a synergistic strategy involving seeded growth combined with surface remediation and applied for the first time in the separation of a multicomponent mixture containing ethyl acetate by pervaporation. By regulating the synthesis conditions, a continuous Al-Fum membrane with thickness of 1.7 μm was initially grown within the innermost part of a uniform seed layer. Subsequently, a chitosan (CS) layer was introduced onto the membrane to fabricate the Al-Fum@CS membrane. This CS layer significantly modifies the defects existing in the membrane surface. The obtained Al-Fum@CS membrane with the thickness of around 1.8 μm is dense and has strong hydrophilicity. It can preferentially separate water from a ternary azeotropic mixture of water–ethanol–ethyl acetate and displays high pervaporation performance with a permeation flux of 1.88 kg/(m2·h) and a separation factor of ∼6000 at 60 °C. Especially, the Al-Fum@CS membrane can be continuously operated for more than 150 h without any obvious change in separation performance, showing excellent ultrahigh stability. Moreover, the as-prepared membrane has good acid resistance and reusability in complex environments according to the results of multiple mixture pervaporation experiments. Therefore, the Al-Fum@CS tubular membrane has great industrial application potential for the purification of ethyl acetate produced from the esterification reaction.
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