Imperial College London

Dr Florence Gschwend

Faculty of EngineeringDepartment of Chemical Engineering

Honorary Research Fellow



f.gschwend12 Website




329Bone BuildingSouth Kensington Campus





Publication Type

8 results found

Malaret F, Gschwend FJV, Lopes JM, Tu WC, Hallett Jet al., 2020, Eucalyptus Red Grandis pretreatment with protic ionic liquids: effect of severity and influence of sub/super-critical CO2 atmosphere on pretreatment performance, RSC Advances: an international journal to further the chemical sciences, Vol: 10, Pages: 16050-16060, ISSN: 2046-2069

Deconstruction of lignocellulosic biomass with low-cost ionic liquids (ILs) has proven to be a promising technology that could be implemented in a biorefinery to obtain renewable materials, fuels and chemicals. This study investigates the pretreatment efficacy of the ionoSolv pretreatment of Eucalyptus red grandis using the low-cost ionic liquid triethylammonium hydrogen sulfate ([N2220][HSO4]) in the presence of 20 wt% water at 10% solids loading. The temperatures investigated were 120 °C and 150 °C. Also, the influence of performing the pretreatment under sub-critical and supercritical CO2 was investigated. The IL used is very effective in deconstructing eucalyptus, producing cellulose-rich pulps resulting in enzymatic saccharification yields of 86% for some pretreatment conditions. It has been found that under a CO2 atmosphere, the ionoSolv process is pressure independent. The good performance of this IL in the pretreatment of eucalyptus is promising for the development of a large-scale ionoSolv pretreatment processes.

Journal article

Gschwend F, Chambon C, Biedka M, Brandt-Talbot A, Fennell P, Hallett Jet al., 2019, Quantitative glucose release from softwood after pretreatment with low-cost ionic liquids, Green Chemistry, Vol: 21, Pages: 692-703, ISSN: 1463-9262

Softwood is an abundantly available feedstock for the bio-based industry, however, achieving cost-effective sugar release is particularly challenging owing to its guaiacyl-only lignin. Here, we report the highly effective pretreatment of the softwood pine (Pinus sylvestris) using ionoSolv pretreatment, a novel ionic liquid-based lignocellulose fractionation technology. Three protic, low-cost ionic liquids, 1-butylimidazolium hydrogen sulfate, triethylammonium hydrogen sulfate and N,N-dimethylbutylammonium hydrogen sulfate, were used to fractionate the biomass into a carbohydrate-rich pulp and a lignin. The carbohydrate-rich pulp was hydrolysed into fermentable sugars by enzymatic saccharification. Under the most successful pretreatment conditions, quantitative glucose release from the pulp was achieved, which equates to a projected glucose release of 464 mg per gram of pine wood entering the process. We further intensified the process by increasing the solid to solvent ratio up to 1:2 g/g while maintaining saccharification yields of 75% of the theoretical maximum. We also demonstrate for the first time that N,N-dimethylbutylammonium hydrogen sulfate, [DMBA][HSO4] is an excellent low-cost pretreatment solvent, surpassing the pretreatment effectiveness of its symmetrically substituted analogue triethylammonium hydrogen sulfate. This shows that ionoSolv pretreatment with protic hydrogen sulfate ionic liquids is a truly feedstock-independent pretreatment option, further increasing the commercial potential of this pretreatment technology.

Journal article

Gschwend FJV, Brandt-Talbot A, Malaret FJ, Shinde S, Hallett JPet al., 2018, Rapid pretreatment of Miscanthus using the low-cost ionic liquid triethylammonium hydrogen sulfate at elevated temperatures, Green Chemistry, Vol: 20, Pages: 3486-3498, ISSN: 1463-9262

Deconstruction with low-cost ionic liquids (ionoSolv) is a promising method to pre-condition lignocellulosic biomass for the production of renewable fuels, materials and chemicals. This study investigated process intensification strategies for the ionoSolv pretreatment of Miscanthus X giganteus using the low-cost ionic liquid triethylammonium hydrogen sulfate ([TEA][HSO4]) in the presence of 20 wt% water, using high temperatures and a high solid to solvent loading of 1:5 g/g. The temperatures investigated were 150, 160, 170 and 180°C. We discuss the effect of pretreatment temperature on lignin and hemicellulose removal, cellulose degradation and enzymatic saccharification yields. We report that very good fractionation can be achieved across all investigated temperatures, including an enzymatic saccharification yield exceeding 75% of the theoretical maximum after only 15 min of treatment at 180°C. We further characterised the recovered lignins which established some tunability of the hydroxyl group content, subunit composition, connectivity and molecular weight distribution in the isolated lignin while maintaining maximum saccharification yield. This drastic reduction of pretreatment time at increased biomass loading without a yield penalty is promising for the development of a commercial ionoSolv pretreatment process.

Journal article

Hallett J, Fennell P, Gschwend F, Brandt-Talbot A, Kelsall Get al., 2018, Process for the extraction of metal pollutants from treated cellulosic biomass, CN108291033 (A)

The present invention relates to a process for extracting oxidised metal pollutants from treated cellulosic or lignocellulosic biomass to recover the metal. The treatment also generates a cellulosic or lignocellulosic biomass which can to be used as a feedstock for biofuel, for making cellulose containing materials, and provides a source of other renewable chemicals.


Gschwend FJV, Brandt-Talbot A, Chambon CL, Hallett JPet al., 2017, Ultra-Low Cost Ionic Liquids for the Delignification of Biomass, Ionic Liquids: Current State and Future Directions, Editors: Shiflett, Scurto, Publisher: American Chemical Society, Pages: 209-223, ISBN: 9780841232136

Low-cost pretreatment of lignocellulosic biomass is an essential next step toward large-scale deployment as renewable liquid fuels, materials or chemicals. Ionic liquids (ILs) are highly effective at pretreatment, but high IL cost has hindered commercial viability. We have recently developed low-cost (ca. $1/kg) ILs, such as triethylammonium hydrogen sulphate, for pretreatment. In this chapter we discuss the fractionation of the grass Miscanthus x giganteus, wherein we deconstruct the lignocellulosic matrix into a cellulose-rich pulp, a recovered lignin fraction and an organic distillate. More than 80% of the lignin and quantitative hemicelluloses are removed during extraction. This results in 70-90% glucose release during enzymatic saccharification. The IL can also be successfully recovered and reused, with >99% IL recovery and minimal effects on efficiency of extraction. A detailed mass balance of all components and subsequent economic analysis revealed this efficient pretreatment with an ultra-low cost IL could result in an economically viable pretreatment process.

Book chapter

Fennell PS, hallett J, Brandt-Talbot A, Gschwend Fet al., 2017, An economically viable ionic liquid for the fractionation of lignocellulosic biomass, RSC Green Chemistry, Vol: 19, Pages: 3078-3102, ISSN: 1757-7047

Cost-effective fractionation (pretreatment) of lignocellulosic biomass is necessary to enable its large-scale use as a source of liquid fuels, bio-based materials and bio-derived chemicals. While a number of ionic liquids (ILs) have proven capable of highly effective pretreatment, their high cost presents a barrier to commercial viability. In this study, we investigate in detail the application of the low-cost (ca. $1 kg−1) ionic liquid triethylammonium hydrogen sulfate for the fractionation of the grass Miscanthus x giganteus into a cellulose rich pulp, a lignin and a distillate. We found that up to 85% of the lignin and up to 100% of the hemicellulose were solubilized into the IL solution. The hemicellulose dissolved mainly in monomeric form, and pentoses were partially converted into furfural. Up to 77% of the glucose contained in the biomass could be released by enzymatic saccharification of the pulp. The IL was successfully recovered and reused four times. A 99% IL recovery was achieved each time. Effective lignin removal and high saccharification yields were maintained during recycling, representing the first demonstration that repeated IL use is feasible due to the self-cleaning properties of the non-distillable solvent. We further demonstrate that furfural and acetic acid can be separated quantitatively from the non-volatile IL by simple distillation, providing an easily recoverable, valuable co-product stream, while IL degradation products were not detected. We further include detailed mass balances for glucose, hemicellulose and lignin, and a preliminary techno-economic estimate for the fractionation process. This is the first demonstration of an efficient and repeated lignocellulose fractionation with a truly low-cost IL, and opens a path to an economically viable IL-based pretreatment process.

Journal article

Gschwend FJ, Brandt A, Chambon CL, Tu WC, Weigand L, Hallett JPet al., 2016, Pretreatment of Lignocellulosic Biomass with Low-cost Ionic Liquids., Jove-Journal of Visualized Experiments, Vol: 114, ISSN: 1940-087X

A number of ionic liquids (ILs) with economically attractive production costs have recently received growing interest as media for the delignification of a variety of lignocellulosic feedstocks. Here we demonstrate the use of these low-cost protic ILs in the deconstruction of lignocellulosic biomass (Ionosolv pretreatment), yielding cellulose and a purified lignin. In the most generic process, the protic ionic liquid is synthesized by accurate combination of aqueous acid and amine base. The water content is adjusted subsequently. For the delignification, the biomass is placed into a vessel with IL solution at elevated temperatures to dissolve the lignin and hemicellulose, leaving a cellulose-rich pulp ready for saccharification (hydrolysis to fermentable sugars). The lignin is later precipitated from the IL by the addition of water and recovered as a solid. The removal of the added water regenerates the ionic liquid, which can be reused multiple times. This protocol is useful to investigate the significant potential of protic ILs for use in commercial biomass pretreatment/lignin fractionation for producing biofuels or renewable chemicals and materials.

Journal article

Villar Garcia IJ, Fearn S, De Gregorio GF, Ismail NL, Gschwend FJV, McIntosh AJS, Lovelock KRJet al., 2014, The outer atomic ionic liquid-gas surface: a low energy ion scattering study, Chemical Science

Journal article

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