No. 317: Produce glucose from paper with the help of the characteristics of ionic liquid (September 26, 2011)

Ionic liquid exists as liquid at normal temperature, and it is used for electrolyte of lithium-ion batteries. Research activities to produce glucose from used paper and used cotton with the help of the characteristics of ionic liquid are under way. Hiroyuki Ohno, a professor of Tokyo University of Agriculture and Technology, is one of the researchers. He made ionic liquid by combining various compounds in a container. One of the resulting ionic liquid compounds separated like water and oil at higher than 25 degrees centigrade but intermixed uniformly at lower than 25 degrees centigrade. It is rather unusual to have a reaction that different substances intermix by reducing temperature.

He modified cellulase that is the enzyme to resolve cellulose, the main substance of paper and cotton. He made a complex of enzyme by uniting appropriate elements with the surface of cellulase so that it is soluble in ionic liquid but insoluble in water. He tries to change cellulose to glucose using this complex enzyme. If cellulose and the complex enzyme are put in the mixed solution of water and ionic liquid at lower than 22 degrees centigrade, they intermix and facilitate the chemical reaction that cellulose revolves to become glucose.

Subsequently, heat the mixed solution to increase the temperature to higher than 25 degrees centigrade, and water and ionic enzyme separate. Because glucose is soluble in water, glucose can be produced by collecting the water layer. In addition, because the ionic liquid layer contains the enzyme complex, it can be reused for the reaction to change cellulose to glucose. It is possible to have the chemical reaction in the night when temperature is low and collect the reaction product in the morning when temperature is high. That is, the process is rather energy-saving. The professor plans a joint development with paper companies.