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Building a spent grain biorefinery based with low cost ionic liquids

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  • Full or part time
    Dr Jason Hallett
    Dr A Brandt-Talbot
  • Application Deadline
    No more applications being accepted
  • Funded PhD Project (European/UK Students Only)
    Funded PhD Project (European/UK Students Only)

Project Description

Summary. A fully funded PhD project at Imperial College London on the application of low-cost ionic liquids to the processing of biomass. Target application is the production of biofuels and value-added products, including proteins, from brewers spent grain (BSG, a waste biomass). We will use the ionoSolv (BioFlex) process to fractionate BSG into cellulose, lignin and protein product streams and evaluate biofuel and biomaterial product options (nanocellulose, lignin carbon fibres, biobased composites) from these streams. The ionoSolv process is under commercial development by Lixea LTD, an Imperial College spin-out company, and data sharing on process development will continue throughout the project.

Background. Spent grain is the biomass residue left after brewing, distilling and 1st generation bioethanol production. It is one of the major industrial biomass by-products in the UK and worldwide. Spent grain consists of 20% cellulose, 30% hemicellulose (arabinoxylan), 30% lignin and lipids, and 20% protein. It is currently sold for low-value animal feed. The nutritional value lies solely in the protein content (~20%), and the high content of fibre limits it usability for feeding ruminants, such as cows and sheep. Attempts have been made to enhance spent grain by fractionating it into higher quality feed for a larger variety of animals, including high protein content feed for sustainable aquaculture, while providing separate carbohydrate, furfural and lipid fractions for other value-added applications such as biosurfactants, bio-derived chemicals and liquid biofuels, increasing the over-all value derived from spent grain.

Protein extractions by other means have been attempted, for example alkaline and enzyme, but they are associated with challenges such as poor yields, water economy, and protein quality. Detergents and other additives are often needed to improve yields and quality. Recently, protein extraction with deep eutectic solvent has been reported, with high protein solubilisation but only moderate recovery. IonoSolv pretreatment of biomass is a patented new biomass fractionation process developed at Imperial College (pilot-scale development by Lixea LTD, but has not been optimised for protein-rich lignocellulose such as spent grain.

Project. Preliminary data show that ionosolv ILs can successfully extract protein from biomass, leaving a cellulose rich fraction that can be turned into bio-based fuels or chemicals. The protein can be easily recovered in a separate fraction and has been shown to be pre-hydrolysed, making it easily digestible by the stomach. In this project, we will optimise the extraction, recovery and purity of the proteins from spent grain while maximising the quality of the other fractions, the spent grain will be obtained from a UK brewery. We may also explore the production of furfural from spent grain.

The project will also valorise other side streams produced in the biorefinery. We will use the recovered lignin to produce carbon fibres. Carbon fibre reinforced composites are extremely strong, durable materials and very light-weight. They can replace steel and aluminium in the construction of cars, aircraft and wind turbine blades, leading to significant CO2 emissions due to lower weight. However, today’s carbon fibres are made from the expensive, fossil fuel-derived precursor polyacrylonitrile (PAN) in an energy-intensive process involving toxic chemicals such as HCN. We will use lignin to draw lignin fibres by melt-spinning and other fibre drawing techniques. Creating carbon fibres from lignin has the potential to sever fossil fuel dependency of carbon fibre production, reduce the environmental impact of the process and drastically cut the cost of carbon fibres by more than 75%, while simultaneously improving economic performance of biofuel production. We will also composite the lignin with cellulose to create biobased renewable composites.

You will join two dynamic interdisciplinary research teams in Chemistry and Chemical Engineering focusing on biomass fractionation and characterisation and lignin based materials production, as well as an adventurous, pragmatic start-up team. Applicants should have an excellent understanding of physical science and / or chemical engineering, combined with outstanding teamwork and communication skills and a deep interest in biomass conversion, and a passion for transforming the chemical industry. The studentship is funded for 3 years and includes a London weighted stipend and home tuition fees. Expected start-date is October 2020.

Any questions and to apply, please email [Email Address Removed] or [Email Address Removed]. We require a CV, a cover letter and details of two independent referees. Open until filled with a closing date no later than 22 May 2020.

Funding Notes

Fully funded UK/EU applicants (stipend + fees)


1) Chambon, C.L., Chen, M., Fennell, P.S., Hallett, J.P. “Efficient Fractionation of Lignin-and Ash-Rich Agricultural Residues Following Treatment with a Low-Cost Protic Ionic Liquid.”, Front. Chem., 7, (2019), 246.
2) Gschwend, F.J.V., Chambon, C.L., Biedka, M., Brandt-Talbot, A., Fennell, P.S., Hallett, J.P. “Quantitative glucose release from softwood after pretreatment with low-cost ionic liquids”, Green Chem., 21, (2019), 692-703.
3) Chambon, C.L., Mkhize, T.Y., Reddy, P., Brandt-Talbot, A., Deenadayalu, N., Fennell, P.S., Hallett, J.P. “Pretreatment of South African sugarcane bagasse using a low-cost protic ionic liquid: a comparison of whole, depithed, fibrous and pith bagasse fractions”, Biotechnol. Biofuels, 11, (2018), 247.
4) Gschwend, F.J.V., Malaret, F., Shinde, S., Brandt-Talbot, A., Hallett, J.P. “Rapid pretreatment of Miscanthus using the low-cost ionic liquid triethylammonium hydrogen sulfate at elevated temperatures” Green Chem., 20, (2018), 3486-3498.
5) Weigand, L., Mostame, S., Brandt-Talbot, A., Welton, T., Hallett, J.P., “Effect of pretreatment severity on the cellulose and lignin isolated from Salix using ionoSolv pretreatment.” Faraday Discuss. 202, (2017), 331-349.
6) Brandt-Talbot, A., Gschwend, F.J.V., Fennell, P.S., Lammens, T.M., Tan, B., Weale, J., Hallett, J.P., “An economically viable ionic liquid for the fractionation of lignocellulosic biomass.” Green Chem. 19, (2017), 3078-3012.
7) Gschwend, F.J.V., Tu, W-C., Chambon, C.L., Weigand, L., Brandt, A., Hallett, J.P., “Pretreatment of Lignocellulosic Biomass with Low-cost Ionic Liquids.” J. Vis. Exp., (2016), e54246-e54246.
8) Brandt, A., Chen, L., van Dongen, B.E., Welton, T., Hallett, J.P., “Structural changes in lignins isolated using an acidic ionic liquid water mixture.” Green Chem. 17, (2015), 5019-5034.
9) George, A., Brandt, A., Zahari, S.M.S.N.S., Klein-Marcuschamer, D., Parthasarathi, R., Sun, N., Saithitsuksanoh, N., Shi, J., Stavila, V., Tran, K., Singh, S., Holmes, B., Welton, T., Simmons, B.A., Hallett, J.P., “Design of low-cost ionic liquids for lignocellulosic biomass pretreatment.” Green Chem. 17, (2015), 1728-1734.
10) Chen, L., Sharifzadeh, M., Mac Dowell, N., Welton, T., Shah, N., Hallett, J.P., “Inexpensive ionic liquids: [HSO4]--based solvent production at bulk scale.” Green Chem. 16, (2014), 3098-3106.

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