266474 Supercritical CO2 Extraction of 1-Butanol From Aqueous Solutions Using a Hollow Fibre Membrane Contactor
Hollow fibre membrane contactors have recently received much attention in a number of separation or purification processes due to their large specific areas, enhancing mass transfer and therefore extraction efficiencies. The so called porocritical extraction process couples the porosity of a hollow fibre membrane contactor (HFM) with the high diffusivity of a supercritical fluid (generally carbon dioxide) to create a non-dispersive contact between solvent and aqueous feed, allowing a high throughput capacity without flooding or foaming issues independently of density difference between phases. This study presents the application of this technique to the separation of 1-butanol from aqueous solutions. 1-butanol, or “biobutanol” is a second generation biofuel that can be produced by anaerobic fermentation; however, its yield is currently limited to less than 5 % by mass of the fermentation broth and is normally recovered by distillation, which is highly energy intensive. In this work, the efficiency of a lab-scale HFM contactor in the supercritical CO2 extraction of 1-butanol from a model water/1-butanol mixture and from an actual fermentation broth is studied under a range of different flow rates, solvent-to-feed ratios and pressure conditions. Packed column fractionation was also carried out to enable comparison of extraction efficiency under a limited range of conditions.