Pebax/POSS Molecular-Level Mixed Matrix Membranes for Pervaporation Recovery of Ethanol From Aqueous Solutions

Novel polyether-block-amide/polyhedral oligosilsesquioxane (Pebax/POSS) molecular-level mixed matrix membranes (MMMs) have been developed in this study for ethanol recovery via pervaporation with synergized performance. Two types of POSS; namely, octa(3-hydroxy-3-methylbutyldimethylsiloxy) (AL0136) and disilanolisobutyl  (SO1440), were incorporated into Pebax membranes. The effects of feed ethanol concentration and operating temperature have been analysed. MMMs exhibit the highest performance at 2 wt.% POSS loading; both permeation flux and separation factor of ethanol/water reach the maximum values, which are 183.5 g/m²h and 4.6 for Pebax/AL0136 and 125.8 g/m²h and 4.1 for Pebax/SO1440, respectively. Pebax/AL0136 MMMs give better performance than that of Pebax/SO1440 MMMs, probably due to its higher affinity towards ethanol. Experimental results also show that increasing ethanol concentration in feed results in an increase in flux but a decrease in separation factor. Meanwhile, both flux and separation factor can be enhanced by increasing operating temperature. The changes in driving force, cluster formation, membrane swelling and interaction among permeating molecules account for the resultant performance trends. This work may potentially opens up new perspectives for the development of a novel biofuel recovery process from fermentation broths.