ZIF-L based mixed matrix membranes for acetone-butanol-ethanol (ABE) recovery from diluted aqueous solution

Abstract

Enrichment of bio-based platform compound ABE (acetone-butanol-ethanol) from extremely diluted raw medium is pivotal for the full utilization of ABE and selective conversion of them into value-added chemicals. Vapor permeation process through mixed matrix membranes (MMMs) demonstrates an energy-efficient solution to this challenge. Here, MMMs, by doping two-dimensional ZIF-L nanosheets with porous skeletons into an oleophilic matrix (poly-R-siloxane), were produced to synchronously enrich ABE from the simulated fermentation broth (total ABE of 3.0 wt% or lower, and composition of A: B: E = 3: 6: 1). The good compatibility of ZIF-L and polymer matrix renders MMMs with significantly improved flux and separation factor of organics over water. Typically, MMMs incorporating 5.0 wt% of ZIF-L fillers contribute to an increase of 72.3% and 106% in liquid flux and butanol/water separation factor, respectively, when compared with the pure polymer membranes. Through ZIF-L based MMMs, the water content in the permeant is controlled below 30 wt%, which is a prerequisite for utilization of ABE in the real bio-refinery industry.