Physical insight into switchgrass dissolution in the ionic liquid 1-ethyl-3-methylimidazolium acetate

Journal Article · Wed Jan 01 00:00:00 EST 2014 · ACS Sustainable Chemistry & Engineering

DOI:https://doi.org/10.1021/sc500088w· OSTI ID:1131512

Wang, Hui ^[1]; Gurau, Gabriela ^[1]; Pingali, Sai Venkatesh ^[2]; O'Neil, Hugh ^[2]; Evans, Barbara R ^[2]; Urban, Volker S ^[2]; Heller, William T ^[2]; Rogers, Robin D ^[1]

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1. University of Alabama, Tuscaloosa
2. ORNL

Small-angle neutron scattering was used to characterize solutions of switchgrass and the constituent biopolymers cellulose, hemicellulose, and lignin, as well as a physical mixture of them mimicking the composition of switchgrass, dissolved in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate. The results demonstrate that the IL dissolves the cellulose fibrils of switchgrass, although a supramolecular biopolymer network remains that is not present in solutions of the individual biopolymers and that does not self-assemble in a solution containing the physical mixture of the individual biopolymers. The persistence of a network-like structure indicates that dissolving switchgrass in the IL does not disrupt all of the physical entanglements and covalent linkages between the biopolymers created during plant growth. Reconstitution of the IL-dissolved switchgrass yields carbohydrate-rich material containing cellulose with a low degree of crystallinity, as determined by powder X-ray diffraction, which impacts potential down-stream uses of the biopolymers produced by the process. The data suggests that the use of chemical additives which would break bonds that exist between the lignin and hemicellulose might improve the purity of the resulting product, but may not be able to disrupt the highly physically-entangled biopolymer network sufficiently to facilitate their separation.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Structural Molecular Biology (CSMB)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1131512
• Journal Information: ACS Sustainable Chemistry & Engineering, Vol. 2, Issue 5; ISSN 2168--0485
• Country of Publication: United States
• Language: English