Application of ionic liquids for effective use of woody biomass

Ionic liquids are salts that have melting points around ambient temperature and unique characteristics, such as high solubility, extremely low volatility, incombustibility and low viscosity. Application of ionic liquids in wood processing technology has attracted attention and is expected to promote further use of wood. They are effective as wood-preserving agents to enhance decay-resistance and also improve fire resistance of wood. Ionic liquids have been used as reaction solvents for preparing various cellulose derivatives or composites with other materials. Attempts have been made to use ionic liquids in pretreatments for enzymatic hydrolysis when producing bio-ethanol from cellulose or wood. Ionic liquids also have been shown to be effective for dissolution of cellulose or wood, forming the basis for studies into the separation of cellulose, hemicellulose and lignin from wood. The effective separation of these components is essential for chemical use of wood, and ionic liquid treatment thus has potential as an enabling technique in biorefineries. Moreover, ionic liquids induce depolymerization of solubilized wood polymers, which may be applicable to the production of useful chemicals from wood polymers such as cellulose, hemicellulose and lignin.