Hydrophobic ultrathin MOF membranes with tuning pore structure for efficient alcohol-permselective pervaporation

Alcohol-permselective pervaporation is a breakthrough technology in industrial separation applications. A high-flux pervaporation membrane is demanded in cost saving. In this study, an ultrathin metal-organic framework (MOF) membrane was formed on a porous polymer substrate using a hydroxyl salt induced in situ growth method. Then, the obtained MOF membrane was modified through a sulfidation strategy to enhance the transport of alcohol molecules. The aperture of the MOFs was enlarged to form a hollow structure. Subsequently, polydimethylsiloxane was spin-coated on the MOF membrane to eliminate the grain boundary defects and improve the hydrophobicity, without increasing the thickness of the MOF layer. Based on the ultra-fast transport channels, the modified MOF membrane exhibited an ultrahigh flux of 11.6 kg m−2 h−1 with comparable separation factors for 5 wt% ethanol aqueous solution at 60 °C. The diffusion mechanism of alcohol molecules was confirmed by the molecular dynamic simulation.