Imperial College London

Prof Jason P. Hallett

Faculty of EngineeringDepartment of Chemical Engineering

Professor of Sustainable Chemical Technology



+44 (0)20 7594 5388j.hallett Website




228bBone BuildingSouth Kensington Campus





Ionic Liquid Based Biorefining: We continue to develop our group's core technology, the ionoSolv biomass fractionation process, to take advantage of the unique opportunities present in an ionic liquid based biorefinery and identify the key science underpinning our concept. The ionoSolv biorefinery will produce biofuels, sugars and materials from lignocellulosic biomass by first using specially designed ionic liquids to separate the biomass components (lignin, cellulose, hemicelluloses). All aspects of the separations process and several aspects of the conversions (specifically, the initial chemical- and bio-catalytic breakdown steps) are under active development, particularly important questions related to ionic liquid impact on sugar yield and cellulose quality and solvent recovery and recycling. The polysaccharides that are separated (cellulose, hemicelluloses) are either developed into hig-value materials (dissolving pulp, micro- and nano cellulose) or enzymatically hydrolysed to fermentable sugars, with the impact of residual ionic liquid minimalized through a multi-pronged strategy involving solvent design and novel separations. This requires an investigation into the specific interactions of ionic liquids with the biological catalysts (enzymes, whole cells) vital to bioconversions, utilizing a variety of chemical biology-based tools. 

We're also growing our materials research on cellulose, lignin and furfural platforms. Lignin-based materials (resins, composites), cellulose-based materials (composities, textiles) and furfural-based surfactants are all under active investigation as biorenewable solutions to the growing bioeconomy.

This is by nature a multi-disciplinary research problem. The underpinning molecular-scale chemical interactions of ionic liquids with biomass, proteins and whole cells will determine the productivity of the biorefinery. The impact of these individual elements on the overall process requires a detailed understanding of both the complex intermolecular interactions driving ionic liquid behavior and an appreciation for how these interactions can impact a chemical process. This places the research firmly at the interface between chemistry and chemical/biomolecular engineering.


Ionic Liquids: Ionic liquids (ILs) are a diverse group of salts that are liquid at ambient temperature.  ILs are polar solvents with varying degrees of hydrogen-bonding ability, negligible vapour pressures under process-relevant conditions and a wide range of tunable solvent properties. ILs have proven highly effective solvents for use in cellulose processing and have recently been demonstrated as effective at lignocellulose pretreatment and biomass fractionation. Anions with high hydrogen-bond basicity, such as chloride or acetate, yield ILs that dissolve cellulose, while bifunctional (protic and hydrogen-bond basic) anions can be employed to de-lignify biomass in partially aqueous ILs. This route simplifies the biorefining process, yielding potential energy savings. While ILs are ideal media for biomass deconstruction, the impact on bioconversions (e.g. biotolerance, IL recyclability) and opportunities for further conversions remain unknown. We explore the fundamental science underlying IL interactions in biocatalytic systems and developing efficient separations for biomass deconstruction and IL recovery. This requires an in-depth knowledge of IL solution behavior and interactions with proteins and cell membranes, the chemistry underlying biomass deconstruction, and the process variables essential to integrated biorefining.

silwood park

Lana, Latiffah, Selina, and Shahrul at the Miscanthus plot at Silwood Park

Deconstruction of biomass using ionic liquids: ILs can effectively pretreat numerous feedstocks by separating the components (cellulose, hemicelluloses, lignin). This can be achieved by two main routes: dissolution or de-lignification. We focus on the latter route (the ionoSolv process) due to much lower cost, higher water tolerance (reduced energy inputs for biomass or IL drying), better lignin removal, accessible lignin recovery (without destroying the IL) and simplified processing. Our research in this area focusses on the chemical interactions between ILs and the individual biopolymers leading to better separations, and the impact of the ILs on downstream processing to cellulosic materials, biofuels and platform chemicals.

We are particularly interested in the circular bioeconomy. As such, we have widened teh feedstock range to include waste wood (construction, demolitio nand post-consumer waste) and phytoremediation crops grown on marginal land. These lower-cost feedstocks will greatly improve the economics of biorefining and only ionic liquids can provide an integrated solution of decontamination and fractionation.

We developed a series of ultra-low-cost ionic liquids specifically for this purpose. These have similar production costs to bulk organic solvents such as toluene, acetone or ethanol. Our ionoSolv process therefore represents a truly economical and sustainable option for biorefining.

Vaccine stabilisation: ionic liquids for the elimination of the cold chain: The aim of this research is to reduce the cost of vaccination using biocompatible ionic liquids as stabilising agents.

Vaccination programmes are expensive, and this is due mainly to the cold chain, which costs $200–300 million per year and can account for up to 80 per cent of overall vaccination costs. Some vaccines require ultra-cold storage (temperatures below -80°C) which leaves them challenging to distribute worldwide. This is particularly true in resource-limited countries that lack cold storage infrastructure or have remote populations far from major cities, making vaccine programmes prohibitively expensive.

The most important challenges to effective cold chains are poor temperature control and maintenance leading to the reduced potency of vaccines, inadequate availability of vaccines due to insufficient cold chain capacity, and a lack of the latest cold storage technology. This is especially difficult during transport and storage, as portable freezers have limited running times, and very remote areas do not have access to cold storage.

Our approach is to eliminate the cold chain altogether by making vaccines that can withstand more natural temperatures. We have focused on two aspects of vaccine storage – one approach for protein-based vaccines and a separate approach for RNA or DNA-based vaccines. Our biocompatible ionic liquids act as both thermal stabilising agents and delivery enhancers, providing room temeprature storage of RNA vaccines on the timescale of years.

Other Ionic Liquids Research:

Process and Techno-economic Modelling of Ionic Liquid Biorefining

Catalytic Production of Platform Chemicals from Biomass using Ionic Liquids 

Interactions of Ionic Liquids with Biopolymers 

Recycling Ionic Liquids

Demetallization of Waste for Metal Recycling

Corrosion in Ionic Liquids