(393c) N-Butanol Separation From Aqueous Solution By Pervaporation Using Composite PDMS Membrane

Butanol is attracting more and more research interest as a second generation biofuel and due to environmental and energy concerns. Butanol can be produced through fermentation process, which is environmental friendly and sustainable, other than petrochemical process. Fermentative butanol usually exists in dilute aqueous solution. Therefore, we need to recover butanol from this dilute solution to get pure or high concentration butanol. There are several popular ways to separate butanol: pervaporation, gas stripping, adsorption and etc. Among them, pervaporation is an outstanding method as it offers higher selectivity and lower energy consumption compared to other techniques. Pervaporation is a membrane based technique and selective membrane is the key factor. Poly (dimethyl siloxane) (PDMS) membrane offers highest butanol separation factor and is widely used for recovering butanol from aqueous solution. However, butanol flux and selectivity of PDMS membranes can still be improved, especially butanol flux. In this work, efforts were made to improve butanol flux and separation factor of composite PDMS membranes. Different membrane thickness, filler material, and operating temperature were tested. Activation energy of PDMS membrane was also evaluated. Among those studied membranes, polytetrafluoroethylene (PTFE) supported PDMS membrane filled with zeolite offered a butanol separation factor of ~60 and butanol flux of 52 g/m²·h. This membrane can concentrate a 15 g/L butanol solution to a ~420 g/L butanol solution with one single pass. This greatly reduces the butanol recovery cost and makes fermentative butanol production more economical.