Pebax/POSS mixed matrix membranes for ethanol recovery from aqueous solutions via pervaporation

Novel mixed matrix membranes made of polyether-block-amide/polyhedral oligosilsesquioxane (Pebax/POSS) have been developed and investigated in this study for ethanol recovery via pervaporation separation. Two types of POSS; namely, octa(3-hydroxy-3-methylbutyldimethylsiloxy) (AL0136) and disilanolisobutyl (SO1440), were incorporated into Pebax membranes. The effects of POSS loading, feed ethanol concentration and feed temperature on pervaporation performance of the newly developed mixed matrix membranes (MMMs) have been studied. The incorporation of POSS nanoparticles improve the pervaporation performance of the hybrid membranes significantly. At 2 wt.% POSS loading, both permeation flux and separation factor of ethanol/water reach maximum values, which are 183.5 g/m2 h and 4.6 for Pebax/AL0136 and 125.8 g/m2 h and 4.1 for Pebax/SO1440, respectively. Pebax/AL0136 MMMs give better performance than Pebax/SO1440 MMMs, probably due to its higher affinity towards ethanol. Experimental results show that an increase in feed ethanol concentration results in an increase in flux, but decreases in separation factor and membrane selectivity. Flux increases but permeability decreases with an increase in operating temperature due to the increase in driving forces and the reduction in permeant sorption, respectively. Separation factor and selectivity are also observed to increase with increasing operating temperature. The changes in driving force, cluster formation, membrane swelling and interaction among permeating molecules play essential roles for the observed trends. This work may provide useful insights of mixed matrix membranes, especially those containing POSS for pervaporation recovery applications.

► Molecular-level mixed matrix membranes are developed for ethanol recovery.
► Incorporating POSS with Pebax polymer significantly improves the separation performance.
► Sorption and permeation characteristics of the MMMs are characterized.
► Increasing temperature enhances both flux and separation factor of the membranes.