De novo synthesis of amino-functionalized ZIF-8 nanoparticles: Enhanced interfacial compatibility and pervaporation performance in mixed matrix membranes applying for ethanol dehydration

Abstract

The incorporation of attainable amine functionality in zeolitic imidazolate framework-8 (ZIF-8) is utilized to enhance the pervaporation performance for ethanol/ water separation applications. Using 2-aminobenzimidazole, a ligand with NH2-functionalized group, displacement of the ZIF-8 original ligand during de novo synthesis while preserving the ZIF-8 initial structure, which produces a novel mixed- linker ZIF material (ZIF-8-NH2) with smaller nanocrystal size, controllable pore size, and enhanced hydrophilicity. A series of different mixed matrix membranes (MMMs) were fabricated by incorporating ZIF-8-NH2 into poly(vinyl alcohol) (PVA) matrix. Various characterization techniques, such as FTIR, 1H NMR, XRD, SEM, TGA, and Contact angle etc. were employed to demonstrate the properties of prepared ZIF nanoparticles and the MMMs. The results indicated that ZIF-8-NH2 and the MMMs were perfectly fabricated, which were attributed to better dispersion and compatibility between them. In particular, 7-ZIF-8-NH2/PVA MMM exhibited a comparable total flux of 142 g/m2·h and water/ethanol separation factor of 925, which were increased by 73 and 524%, on the basis of the pristine PVA membrane. In addition, different nanofillers, APTES crosslinking, ZIF-8-NH2 loading, operating temperature, feed concentration, and membrane stability were evaluated in detail. This study might provide a promising prospect for designing MOF-based MMMs with the introduction of various functional groups.