(544c) Preparation of Cellulose-Rich Materials From Cornstalks In Biodegradable Ionic Liquids

Agricultural wastes such as bagasse, cornstalks, are relatively cheap sources of lignocellulose consisting of lignin, cellulose and hemicellulose. However, most of them are burned as waste without rational use, even causing severe environment contamination. Lignocellulosic materials have aroused wide public concern due to their potential as starting materials for biofuels and other commodity chemicals.¹

The unique physicochemical properties of ionic liquids (ILs), such as non-flammability, negligible vapour pressure, high thermal and chemical stability, have attracted increasing interests in their potential applications in various areas. It is showed that lignocellulosic materials can be dissolved in ILs which are almost imidazolium-based ionic liquids (IBILs)². The differences of solubility among the components of lignocellulose make it possible to separate them from each other. However, the scope of possible applications of imidazolium-based ionic liquids is restricted due to their high cost, toxicity and the non-biodegradability of the imidazolium ring³.

In our work, we obtained cellulose-rich materials via utilizing a kind of economic biodegradable IL, choline acetate ( [ChO][OAc] ), demonstrating the possibility of the partial dissolution and separation of cornstalks after mild grinding. The selected [ChO][OAc] IL presents very low toxicity, due to the benign nature of the cation and its high biodegradation potential which was evaluated under aerobic conditions. Delignification of cornstalks using the [ChO][OAc] IL was successfully achieved that lignin content decreased from 14% of cornstalk raw materials to 2% of undissolved residue under mild conditions. Thus, cellulose-rich materials accounting for 98% could be obtained. Furthermore, the cellulose fibre from [ChO][OAc] solutions can be regenerated to form cellulose membrane on a glass plate. In this way, partial separation of the cornstalk components becomes available with relative efficient, nontoxic and biodegradable ionic liquids.

Reference

1 Suzie S. Y. Tan, Douglas R. MacFarlane, Jonathan Upfal, Leslie A. Edye, William O. S. Doherty, Antonio F. Patti, Jennifer M. Pringle and Janet L. Scott,Green Chem., 2009, 11, 339-345

2 Ning Sun, Mustafizur Rahman, Ying Qin, Mirela L. Maxim, Héctor Rodríguez and Robin D.Rogers, Green Chem., 2009, 11, 646-655

3 Helga Garcia, Rui Ferreira, Marija Petkovic, Jamie L. Ferguson, Maria C. Leitão, H. Q. Nimal  Gunaratne, Kenneth R. Seddon, Luís Paulo N. Rebelo and Cristina Silva Pereira, Green Chem., 2010,  12, 367-369