(443e) Enhanced Separation of n-Butanol From Dilute Aqueous Solutions by Pervaporation Using Poly(dimethyl siloxane) Membranes Filled with Micro- and Nano-Sized Adsorbents

Pervaporation has been widely studied for the separation of close boiling point, azeotropic and other mixtures that are difficult or noneconomical to separate by conventional techniques such as distillation. From an energy consumption point of view, pervaporation is considered as a preferable method for butanol separation from acetone-butanol-ethanol (ABE) fermentation broth, which usually has a low butanol titer of <15 g/L. Poly(dimethyl siloxane) (PDMS) is commonly used in pervaporation for separating organic compounds from a dilute aqueous solution. In this work, the performance of PDMS membranes with various thicknesses (100 μm, 150 μm and 200 μm) was investigated. In general, the butanol concentration in permeate and the separation factor increased with increasing the membrane thickness, which was attributed to improved hydrophobicity of the membrane that limited water transport. With ~15 g/L butanol in the feed solution, the butanol concentration in permeate and the separation factor were 142.8 g/L and 8.3, respectively, when the membrane thickness was 200 μm. Both butanol concentration and separation factor increased greatly when the PDMS membrane was filled with zeolite and other adsorbents, making pervaporation an attractive separation method for butanol recovery and purification from fermentation broth.