(464e) PDMS/Ceramic Composite Membrane in Glycerol Fermentation–PV Coupled Process for Biobutanol Production

Facing the depletion of fossil energy and the pollution of the environment, the development and utilization of biomass fuels have brought dawn to the sustainable development of human beings. Biomass fuel, as a renewable energy, has unparalleled advantages. With the development of biodiesel industry, the production of crude glycerol, as an inevitable by-product in the production of biodiesel, is huge. As we all know, bioconversion of crude glycerol without pretreatment to biofuels is the way to disposal of the surplus crude glycerol. In addition, biomass fuel butanol, which is produced by bio-fermentation, can be used as a clean renewable energy biofuel. At the same time, pervaporation is considered to be the greatest potential separation technology because of its energy-saving and efficiency, as well as no harmful effects on the microorganisms. Therefore, fermentation-PV coupled process is a membrane-based process so as to in-situ separate bio-product from fermentation broth by the alcohol-permselective membranes. PDMS membrane has been attracting more and more attention for the separation of biobutanol by coupling bio-fermentation process especially.

In this work, the PDMS/ceramic composite membrane separated the biobutanol directly from the crude glycerol fermentation broth, which not only relieves the inhibition effect of butanol, but also improves the yield of butanol. The pervaporation performance and the stability of the membrane in batch fermentation and fed-batch fermentation were systematically researched. During 250 h of continuous fed-batch fermentation-PV coupled process, the membrane exhibited high flux of 550 g/ (m² h) and separation factor of 24.1. Furthermore, compared with fermentation, the yield of butanol was increased by 55.6%. In this process, membrane fouling leaded to the degradation of membrane pervaporation performance after 200 h. The SEM, AFM, FT-IR and XPS characterizations demonstrated that the membrane fouling is due to the adsorption of active cells on the surface of PDMS membrane. Nevertheless, the total flux and separation factor of the water-washed membrane were the same as those of the fresh membrane, implying that the effect of membrane fouling on the membrane was reversible.