Strategies for Efficient and Cost-Effective Ionic Liquid Recycle and Product Recovery

Pretreatment with certain ionic liquids (IL) is highly effective at reducing the recalcitrance of a wide variety of lignocellulosic biomass to subsequent hydrolysis to release fermentable sugars. The key to an economically viable and scalable IL pretreatment technology is to develop efficient and cost competitive processes to recovery sugars and lignin and recycle IL for reuse.  We have developed and tested several IL recycle and recovery strategies at the Joint BioEnergy Institute (JBEI). We have developed an improved liquid-liquid membrane extraction method that recovers >90% glucose and >95% xylose at ambient temperature and the recycled IL retains >95% of its original pretreatment efficiency.  Additionally, we evaluated membrane (micro, ultra, and nano-) filtration and electro-dialysis separation technologies in conjunction with our newly developed one-pot IL pretreatment and saccharification process to enable IL recycle and recovery of lignin and fermentable sugars.  Finally, we demonstrated a new regeneration protocol that use solvents precipitating cellulose but are immiscible with IL, a process that eliminates the use of water and facilitates lignin and IL recovery. Comparing with the costly distillation/chromatography, the membrane or phase separation technologies allow easier operation and less energy consumption and show great potentials for developing cost effective IL-based biomass pretreatment technologies.