High-performance UiO-66/polyimide mixed matrix membranes for ethanol, isopropanol and n-butanol dehydration via pervaporation

We have designed novel mixed matrix membranes (MMMs) consisting of UiO-66 nanoparticles and 6FDA-HAB/DABA polyimide for the dehydration of ethanol, isopropanol and n-butanol via pervaporation. The UiO-66 nanoparticles have a particle size of around 100 nm. They can be evenly dispersed in the 6FDA-HAB/DABA polyimide matrix without visible agglomeration even at the highest 30 wt% loading. The incorporation of UiO-66 into the 6FDA-HAB/DABA polyimide not only significantly enhances both free-volume radius and fractional free volume as confirmed by positron annihilation lifetime spectroscopy but also remarkably improves the normalized flux of MMMs for the dehydration of ethanol/water, isopropanol/water and n-butanol/water systems. The MMMs show excellent separation efficiency for the dehydration of isopropanol and n-butanol. At the highest UiO-66 loading of 30 wt%, the MMMs have the water permeability of 0.329 and 0.292 mg m⁻¹ h⁻¹ kPa⁻¹ and mole-based selectivity of 2209 and 14214 respectively for isopropanol/water and n-butanol/water systems, outperforming most literature data. These experimental results strongly suggest the newly developed UiO-66/polyimide MMMs have great potential for isopropanol and n-butanol dehydration via pervaporation.