MCM-41@ZIF-8/PDMS hybrid membranes with micro- and nanoscaled hierarchical structure for alcohol permselective pervaporation

Abstract

Abstract In the alcohol permselective pervaporation process, the hydrophobicity of the membrane usually plays an important role. The microstructure of membrane surface has significant influence on its hydrophobicity. In this study, a MCM-41@ZIF-8/PDMS hybrid membrane with micro- and nanoscaled hierarchical structure was prepared. ZIF-8 nanocrystal in situ grew on the surface of microscaled MCM-41 to fabricate MCM-41@ZIF-8 hybrid particles. These hybrid particles were modified by hydrophobic silane coupling agent to become superhydrophobic, and dispersed in PDMS matrix to form a composite membrane. The hydrophobicity of MCM-41@ZIF-8/PDMS membrane improved because of its hierarchical structure. The alcohol affinity of the membrane was thus enhanced. Moreover, owing to the porosity of MCM-41 and ZIF-8 particles, the flux of the hybrid membrane was significantly improved. The prepared MCM-41@ZIF-8/PDMS hybrid membranes exhibited a relative high flux (2201 g/m2 h) with a separation factor of 10.4 in the separation of 5.0 wt% ethanol/water mixtures. In addition, these membranes can also be used in separating n-butanol/water mixtures with excellent separation performance. Therefore, the membrane is expected to have potential application in alcohol permselective pervaporation.