(638b) Biofuels Production By Fermentation/Pervaporation Coupled Process with Novel Silane Modified Silicalite/PDMS Mixed Matrix Membrane: Effects of Fermentation Components and By-Products

Organic permselective pervaporation membrane technology has been considered to be one of the best among various methods for the recovery of biofuels from fermentation broth. However, in addition to the desired product, fermentative organisms will produce a range of compounds that contain a variety of by-products, which could be potentially problematic for pervaporative separation. For example, during bioethanol fermentation process, the yeast will also produce longer straight-chained and branched alcohols and organic acids. Additionally, biomass pretreatment process can introduce other inhibitors, such as formic acid, acetic acid, and furfural, into the sugar feed stream to the fermentation broth.

In this presentation, the influence of different components in actual bio-ethanol fermentation broths (fermentation medium components, fermentation by-products, and the common inhibitory compounds present in lignocellulosic hydrolysates), and yeast cells on the pervaporation performance of the thin-film VTES modified silicalite/PDMS/PAN composite membrane was investigated in detail. The results showed that the composite membrane can effectively remove formic acid, acetic acid, and furfural present in lignocellulosic hydrolysates. When the model solution with dry yeast cells and the real fermentation broth containing active yeast cells were used, a slightly higher pervaporation flux was found, but the yeast cells had little effect on membrane selectivity. Based on the above results, a membrane bioreactor system comprised of a fermenter and a frame and sheet pervaporation module was developed for continuous ethanol fermentation. Owing to the efficient removal of ethanol from the fermentation broth by VTES modified silicalite/PDMS/PAN composite membrane to alleviate the inhibition to yeast cells, a continuous fermentation/pervaporation coupled process was successfully performed. The composite membrane showed an excellent stability of both flux and selectivity in the coupled process.