Monday, April 29, 2013
Exhibit Hall
Macroalgae (i.e. brown and red seaweeds) have the potential to replace terrestrial biomass as a renewable energy resource. In this work, ionic liquids were used to depolymerize algal biomass into fermentable sugars such as glucose, galactose and xylose. Three brown algal species, Sargassum fulvellum, Laminaria japonica and Undaria pinnatifida were pretreated using the ionic liquid, 1-n-butyl-3-methylimidazolium chloride ([BMIM]Cl) coupled with mineral acids. Results from hydrolysis experiments showed that careful selection of the type of mineral acid as catalyst and control of acid loading could maximize the recovery of sugars. Moreover, optimal reaction time and temperature were determined from kinetic studies on sequential total reducing sugar (TRS) formation and degradation. Structural analyses (XRD and SEM) confirmed the suitability of [BMIM]Cl as solvent for the hydrolysis of the three brown algae. Red macroalgae, Gelidium amansii with a carbohydrate content of 76 wt% was hydrolyzed using acidic ionic liquid, 1-n-butyl-methylimidazolium hydrogen sulfate ([BMIM]HSO4). A novel system using [BMIM]Cl in combination with [BMIM]HSO4 gave optimal sugar yields. A maximum of 64% galactose can be recovered by optimizing the ratio of both ionic liquids. Effects of alkyl chain length as well as anion in the ionic liquid were studied for maximum sugar recovery. Overall, results show the potential of macroalgae in ionic liquid systems as a viable source of fermentable sugars for subsequent biofuel or biochemical production.
ACKNOWLEDGEMENT
This work was supported by Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012-0006693).