Understanding the impact of ionic liquid pretreatment on eucalyptus

• Published in: Biofuels (London) 2010-01, Vol.1 (1), p.33-46
• Main Authors: Çetinkol, Özgül Persil, Dibble, Dean C, Cheng, Gang, Kent, Michael S, Knierim, Bernhard, Auer, Manfred, Wemmer, David E, Pelton, Jeffrey G, Melnichenko, Yuri B, Ralph, John, Simmons, Blake A, Holmes, Bradley M
• Format: Article
• Language: English
• ISSN: 1759-7269; 1759-7277
• DOI: 10.4155/bfs.09.5

Background: The development of cost-competitive biofuels necessitates the realization of advanced biomass pretreatment technologies. Ionic liquids provide a basis for one of the most promising pretreatment technologies and are known to allow effective processing of cellulose and some biomass species. Results & discussion: Here, we demonstrate that the ionic liquid 1-ethyl-3-methyl imidazolium acetate, [C2mim][OAc], induces structural changes at the molecular level in the cell wall of Eucalyptus globulus. Deacetylation of xylan, acetylation of the lignin units, selective removal of guaiacyl units (increasing the syringyl:guaiacyl ratio) and decreased β-ether content were the most prominent changes observed. Scanning electron microscopy images of the plant cell wall sections reveal extensive swelling during [C2mim][OAc] pretreatment. X-ray diffraction measurements indicate a change in cellulose crystal structure from cellulose I to cellulose II after [C2mim][OAc] pretreatment. Enzymatic saccharification of the pretreated material produced increased sugar yields and improved hydrolysis kinetics after [C2mim][OAc] pretreatment. Conclusion: These results provide new insight into the mechanism of ionic liquid pretreatment and reaffirm that this approach may be promising for the production of cellulosic biofuels from woody biomass.