Ionic liquids

A checked version of this page, approved on 1 September 2021, was based on this revision.

Ionic liquids are organic salts that are liquid at room temperature. Because they are salts, they show no volatility. Moreover, they show a high thermal stability. Together this allows for them to be used as green solvents as alternatives to volatile organic compounds. These properties can be used in the pre-treatment of lignocellulosic material by dissolving the material and separating the lignin.^[1] Lignin streams can also be dissolved to allow for further processing.

Feedstock

Ionic liquids are capable of dissolving lignocellulosic biomass. Examples include corn stalks, rice straw, bagasse, pine wood, and spruce wood.^[1] Next to lignocellulosic biomass, lignin streams can be dissolved for further processing.

Process and technologies

Ionic liquids have been shown to dissolve lignin or cellulose, which can decrease its crystalinity and therefore make it more accessible for further processing. Moreover, a full dissolution of lignocellulosic biomass can be used to extract the lignin. The technology can also be combined with hydrolysis to make the cellulose available as sugars for further processing.^[1] Cellulose can be recovered from the solution by the addition of water, ethanol, or acetone, while the ionic liquid can be recovered by pervaporation, reverse osmosis, salting out, or ionic exchange.^[2]

Product

The final product of the process depends on the exact combination of technologies. Generally, a large part of the lignin can be extracted from lignocellulosic material. The resulting lignin can be one of the products, the other begin the remaining lignocellulosic material, where the cellulose is more easily available for further processing.

Technology providers

[space for technology comparison]

RISE (Sweden)

After the LightFibre project showed that kraft lignin and cellulose can be dissolved in an ionic liquid and then wet-spun, the ConCarb project was started to convert lignin and cellulose into carbon fibers, which can be used in light weight composites.^[3]

Patents

Currently no patents have been identified yet.

References

↑ ^a ^b ^c Sang Hyun Lee, Thomas V. Doherty, Robert J. Linhardt, Jonathan S. Dordick, 2009-04-01: Ionic liquid-mediated selective extraction of lignin from wood leading to enhanced enzymatic cellulose hydrolysis. Biotechnology and Bioengineering, Vol. 102, (5), 1368–1376. doi: https://doi.org/10.1002/bit.22179
↑ Valery B. Agbor, Nazim Cicek, Richard Sparling, Alex Berlin, David B. Levin, 2011-11-01: Biomass pretreatment: Fundamentals toward application. Biotechnology Advances, Vol. 29, (6), 675–685. doi: https://doi.org/10.1016/j.biotechadv.2011.05.005
↑ , : Continous stabilization and carbonization of lignin-cellulose for carbon fibers , Last access 30-8-2021. https://www.ri.se/en/what-we-do/projects/continous-stabilization-and-carbonization-of-lignin-cellulose-for-carbon-fibers

[:0-1] Sang Hyun Lee, Thomas V. Doherty, Robert J. Linhardt, Jonathan S. Dordick, 2009-04-01: Ionic liquid-mediated selective extraction of lignin from wood leading to enhanced enzymatic cellulose hydrolysis. Biotechnology and Bioengineering, Vol. 102, (5), 1368–1376. doi: https://doi.org/10.1002/bit.22179

[2] Valery B. Agbor, Nazim Cicek, Richard Sparling, Alex Berlin, David B. Levin, 2011-11-01: Biomass pretreatment: Fundamentals toward application. Biotechnology Advances, Vol. 29, (6), 675–685. doi: https://doi.org/10.1016/j.biotechadv.2011.05.005

[3] , : Continous stabilization and carbonization of lignin-cellulose for carbon fibers , Last access 30-8-2021. https://www.ri.se/en/what-we-do/projects/continous-stabilization-and-carbonization-of-lignin-cellulose-for-carbon-fibers

[1]

[2]

[3]