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Sugar Extraction and Ionic Liquid Recycling Using Alkaline Solutions





Researchers at the Joint BioEnergy Institute (JBEI) have developed a technology to efficiently recycle ionic liquid used for lignocellulosic pretreatment and to reduce the water volume required to produce monomeric sugars from biomass using imidazolium-based ionic liquids, which eliminate the need for enzymes.

In the JBEI approach, adding an alkali solution to extract sugars after the acid catalyzed hydrolysis of biomass in certain imidazolium-based ionic liquids yields two aqueous phases: an ionic liquid-rich phase at the top and a sugar / alkaline rich phase at the bottom. This enables easy recycling of the ionic liquid, lignin recovery, and recovery of the fermentable sugars.

Despite the benefits of ionic liquid pretreatment, such as low vapor pressure, large liquid range and high solvation power for biopolymers, the current high cost of imidazolium-based ionic liquids necessitates efficient recycling. In addition, pretreatment with imidazolium-based ionic liquids, which can greatly accelerate the digestion of the pretreated biomass, typically necessitates large water volumes to wash the biomass prior to enzymatic digestion thus diluting the ionic liquid and increasing the energy needed to recover it. Imidazolium choride ionic liquids have been used to produce sugars and other high value compounds from dissolved biomass in situ, utilizing acid catalysis, eliminating the need to use enzymes. However, there has been limited information on how to recover the released sugars from the ionic liquid and to recover the ionic liquid. The new JBEI technology facilitates the cost effective use of this beneficial group of ionic liquids for pretreatment to achieve high sugar recovery, with reduced water use, and enable ionic liquid recycling.

Chromatography and a system of liquid-liquid extractions using organic solvents have been used to separate IL from sugars. However, the JBEI approach is simpler and achieves better results.

DEVELOPMENT STAGE: Ongoing testing and development.
By combining this system with the acidolysis of biomass in ionic liquid, sugar monomers can be easily extracted from the aqueous ionic liquids. Maximum yields of 53% glucose and 88% xylose can be recovered in the alkaline phase with different pretreatment conditions followed by acidolysis.

STATUS: Patent pending. Available for licensing or collaborative research.


Sun, N., Liu, H., Sathitsuksanoh, N., Stavila, V., Sawant, M., Bonito, A., Tran, K., George, A., Sale, K., Singh, S., Simmons, B., Holmes, B. "Production and extraction of sugars from switchgrass hydrolyzed in ionic liquids," Biotechnology for Biofuels, 2013, 6:39.

Yarris, Lynn. "Joint BioEnergy Institute Researchers Develop Enzyme-free Ionic Liquid Pretreatment," Berkeley Lab News Center, May 9, 2013.


The Joint BioEnergy Institute (JBEI, is a scientific partnership led by the Lawrence Berkeley National Laboratory and including the Sandia National Laboratories, the University of California campuses of Berkeley and Davis, the Carnegie Institution for Science and the Lawrence Livermore National Laboratory. JBEI’s primary scientific mission is to advance the development of the next generation of biofuels.


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