(638a) Modified Ultrafiltration Membranes for Fractionation of Sugars

Today, production of 1^st generation biofuels such as bioethanol from sugar cane and corn starch is well established¹.  Manufacturing processes that include the use of membrane-based unit operations have been described².  However increasing competition between food and energy production has led to significant efforts to convert lignocellulosic biomass into 2^nd generation biofuels.  Unlike 1^st generation biofuels, production of 2^nd generation biofuels is far more complex.  Development of efficient separation and purification operations are essential for production of competitive 2^nd generation drop-in biofuels.  Membrane based separation processes are attractive as they could lead to significant process intensification and hence reduced operating costs³.

Fractionation of sugars prior to fermentation is attractive as one can optimize the fermentation conditions for individual sugars.  Here we have modified commercially available ultrafiltration membranes using layer-by-layer polyelectrolyte deposition.  We investigated modification with poly(sodium 4-styrenesulfonate)/poly(diallyldimethylammonium chloride) and poly(acrylic acid)/poly(diallyldimethylammonium) chloride bilayers.  Modified membranes have been characterized using infrared spectroscopy, atomic force microscopy and scanning electron microscopy. In addition we have measured surface contact angle in order to verify successful surface modification. 

Dead end filtration tests have been conducted in order to determine membrane permeate flux and separation factors for model feed streams consisting of glucose, sucrose and xylose.  Our results indicate that 50 kDa base membranes with 7.5 bilayers of poly(sodium 4-styrenesulfonate)/poly(diallyldimethylammonium chloride) showed the best performance with glucose to sucrose selectivity of more than 11.

Reference:

(1)      Abels, C.; Carstensen, F.; Wessling, M. J. Memb. Sci. 2013, 444, 285–317.

(2)      Qiu, Z.; Zhao, L.; Weatherley, L. Chem. Eng. Process. Process Intensif. 2010, 49, 323–330.

(3)      Drioli, E.; Brunetti, A.; Di Profio, G.; Barbieri, G. Green Chem. 2012, 14, 1561.