ProfessorJason Hallett

Overview
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.

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.

Textile recycling using ionic liquids

We are developing a new chemical technology that creates homogenous textile fibre inputs for recycling and offers the first circular dyeing solution for textile manufacturing. We use low-cost protic ionic liquids to decolour polyester-rich textile waste fibres by swelling the fibres with the solvent and extracting the disperse dyes. This decolourisation step will dissolve the disperse dyes into the ionic liquid without significantly altering the dye chemistry, and without impacting the mechanical integrity of the polyester fibres. Preliminary tests suggest the decolourisation will significantly reduce the dye content in the fibres with colour reduction reaching up to 97%, enabling easier fibre recycling. The dissolved dyes in the ionic liquid can then be reused to dye new synthetic fabrics, creating the novel concept of recycled synthetic dyes. This concept would provide a unique opportunity for more sustainable polyester dyeing with significantly lower chemical inputs through a significant reduction in virgin disperse dye usage as well as dispersing and swelling agents needed in water-based polyester dyeing, also significantly reducing the amount of waste water generated.

Other Ionic Liquids Research:

Metal recycling using ionic liquids

Chemical recycling of plastics using ionic liquids

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