Butanol is an attractive renewable biofuel offering several specific advantages compared to bioethanol such as higher energy content, lower vapor pressure and lower hydrophilicity for fuel formulations. Nevertheless, in the related Acetone-Butanol-Ethanol (ABE) fermentation process, the butanol content is limited to ca. 2 wt% to avoid cytoxicity for the bacteria. With this respect, the recovery of butanol from fermentation broth is a real challenge for the bioindustry. Membrane processes including pervaporation have been identified as key technologies for this application. In this work, grafted multi-block copolymer membranes were developed for the continuous extraction of butanol from dilute aqueous solution. The 'click' grafting of alkyne-functionalized poly(siloxane-urethane-urea) copolymers with azido-polydimethylsiloxane (N3-PDMS) led to different membranes with increasing PDMS contents. The membrane properties were assessed for butanol recovery during sorption and pervaporation experiments with dilute aqueous solution at 50�C. An analysis in terms of structure-property relationships showed that PDMS grafting enabled to increase both membrane permeability and selectivity at the same time. These grafted multi-block materials thus overcame the usual permeability/selectivity trade-off. In addition to being amongst the best polymer membranes reported for this application, these copolymers have the advantages of physical cross-linking and improved processability compared to chemically cross-linked PDMS. Therefore, their unique membrane properties offer great potential for butanol recovery by fermentation/pervaporation coupling in the biofuel industry.

Grafting multi-block copolymers by "click" chemistry for overcoming the membrane permeability/selectivity trade-off: Application to butanol biofuel recovery from dilute aqueous solution

248th National Meeting (2014)

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