(3-Aminopropyl) Triethoxysilane-Modified ZIF-90 Nanoparticle/Polydimethylsiloxane Mixed Matrix Membranes for Ethanol Recovery via Pervaporation

The present study eliminated nonselective defects by amending the MOF-based mixed matrix membrane (MMM) interface with (3-aminopropyl) triethoxysilane (APTES) via Schiff’s base reaction. This modification on the ZIF-90 nanoparticle surfaces enhanced the polydimethylsiloxane (PDMS) matrix interaction in the MMMs. Interfacial defects were then minimized through APTES-ZIF-90 nanoparticle surface alkoxy and PDMS chain hydroxyl group cross-linking. Enhanced chemical interactions between the nanoparticles and the polymeric matrix in the APTES-ZIF-90/PDMS MMMs resulted in higher interface compatibility and separation performance than the ZIF-90 nanoparticle MMMs, which ultimately improved its ethanol affinity and hydrophobicity. When the load of APTES-ZIF-90 nanoparticles was 15% and the temperature was 40 °C, the pervaporation performance of APTES-ZIF-90/PDMS MMMs was optimal, the separation factor was 16.8, and the permeation flux was 223 g/(m2·h). Compared with pure PDMS, the separation factor and permeation flux increased by 91 and 67%, respectively. In addition, stable APTES-ZIF-90/PDMS MMM pervaporation performance was observed after an optimal operation time of 120 h. Overall, the present work presented methods to optimize MOF-based MMMs for enhanced interface morphology and separation performance for ethanol recovery.