Vertically arrayed MOF 1D channels on membrane for ultrafast ethanol-water separation

Biofuel is a promising solution for energy crisis and excessive CO 2 emission. Membrane-based pervaporation process enhances biomass fermentation by constantly separating inhibitory bio-alcohols. However, dominating pervaporation membranes often show low permeation flux and inadequate separation factor. Herein we report the engineering fabrication of flexible composite hollow fiber membranes (HFMs) with oriented metal-organic framework (MOF@ZnO) arrays for ethanol-water separation. The epitaxial MOF arrays containing one-dimensional (1D) transport channels was constructed on HFMs, followed by a superhydrophobic and defect-free surface coating. The arrayed structure induces the flow pattern enhancement near the feed-membrane interface and increases mass transfer area, resulting in self-enhancing separation performance. The synergistic effects of the arrayed surface structure and MOF transport channels on separation performance enhancement were revealed by the experimental and simulation results. Impressively, for the composite HFM, the activation energy of ethanol was found to be lower than that of water. When applied to the pervaporation of a 5 wt% ethanol-water mixture, this membrane achieved an ultrahigh flux along with a good separation factor of 10.5. The versatile strategy is suitable for both inner- and outer-selective HFM modules as well as for various membrane materials which exhibit great potential for industrial applications.