Microporous 3D aluminum MOF doped into chitosan-based mixed matrix membranes for ethanol/water separation

An aluminum metal–organic framework (Al-MOF), [Al(OH)(BPDC)] (DUT-5; BPDC = Biphenyl-4,4′-dicarboxylate), was synthesized using solvothermal reactions. The high surface area and micropores (approximately 1.2 nm) of DUT-5 were characterized using N₂ gas sorption measurements. The thermal stability of DUT-5 and its phase purity were also investigated. The different amounts of DUT-5 (0.1, 0.15, and 0.2 wt%) were successfully incorporated into the chitosan (CS) polymer to prepare a mixed matrix membrane (MMM) for the pervaporation of water/ethanol at 25°C. In particular, when 0.15 wt% of DUT-5 was loaded, the DUT-5@CS MMMs displayed excellent permeability and selectivity in ethanol/water separation. The results indicated that compared with pristine chitosan membranes, the flux of DUT-5@CS membranes with 0.15 wt% loading significantly increased from 315 to 378 (g/m² h⁻¹) and the separation factor from 347 to 3,429. These promising results of the microporous Al-MOF doped into chitosan MMMs reveal its good application potential for the bio-ethanol separation processes.