Application of ionic liquid-liquid chromatography (ILLC) to extractions of metals

The separation of and isolation of metals is one of the first areas of human scientific endeavour. With limited resources on earth, particularly of noble metals together with the ever increasing demand for their use, new technologies that allow them to be produced, recycled and reused are urgently needed. Also, lanthanide and actinide elements are being required in ever increasing quantities in the electrical, electronic and nuclear industries. This proposal describes the development of a new general purpose methodology for the separation of metal compounds and salts. This allows metals recovered from waste such as catalytic converters, electronic scrap, or even from metal ores to be separated and isolated in a pure form that can eventually be put back into commercial use.

The metal separations use the new technology of ionic liquid-liquid chromatography (ILLC) which is an advanced form of countercurrent chromatography (CCC), which uses ionic liquids as one of the phases. Ionic liquids (ILs) have unique properties that can overcome the problems associated with the use of conventional organic solvents in separations. They are composed entirely of ions, are liquid at or near room temperature and can dissolve a wide range of organic and inorganic molecules, especially metal salts. Importantly, ILs have no measurable vapour pressure at ambient temperatures and are generally non-flammable. The relatively high costs of ILs have prevented their extensive use in continuous large-scale systems. Intensified technologies (which require less solvent), will allow the benefits of ILs to be exploited. One such intensified technology is counter current chromatography. Because of their high viscosities, the application of ionic liquids in counter current chromatography systems has been very limited and usually in solution in low viscosity solvents, which negates the purpose of the IL. This limitation was solved at QUILL in collaboration with AECS, to produce a unique, ionic liquid-liquid chromatography system (ILLC). In the proposed research project innovative intensified extraction technologies which combine the unique solvent properties of ionic liquids with the high performance of ILLC will be investigated for the separation of metals (noble, lanthanides, uranium).
The research will be carried out by two teams which are QUILL in Northern Ireland and UCL in London. The collaboration will be strengthened by the involvement of AECS, which will design and build the ILLC instruments based on the project needs. ILLC is a new high performance separation technology that will be studied under this joint proposal in two separate ways. QUILL will carry our research into the direct metal separations and their scale up for commercial use, and design and produce ionic liquids necessary for the research proposed. UCL will study the hydrodynamic and mass transfer phenomena in ILLC and develop predictive models of the process that can be used to maximise the performance. High speed imaging and Laser Induced Fluorescence (LIF) studies will help elucidate the flow and mixing regimes in ILLC separations. Factors such as how flow rates, instrument parameters, ionic liquid and solvent properties and choices affect separations and will be investigated.
The results of the QUILL and UCL studies will be combined to generate scale up protocols for metal separations with the ultimate goal of developing separations that are more efficient, have lower energy demand and use safer less noxious solvents that are currently used in the metal separation industry.

The research will have a direct impact on a number of industries, training of people, and on society, contributing to a safe and secure energy future for the UK.

Industry:
The research will have a significant impact on a number of chemical, nuclear and recycling industries. ILLC is well suited to the recycling of noble metals from recovered catalysts, catalytic converters, and circuit boards (also known as E-waste). The technology is also relevant to spent nuclear fuel reprocessing for reducing the volume and toxicity of the nuclear waste. The following activities will ensure effective communication of the project results to the relevant stakeholders and their engagement for further exploitation of the ILLC technology.
Links with process industries in existing research and industrial consortia: We have substantial links with process industries via QUILL, with an industrial consortium of 12 companies (including Merck, Umicore, and BASF). In addition, the UCL PI is a co-investigator in the multi-institutional EPSRC projects MEMPHIS and PACIFIC (with support from BP, Chevron, P&G, EDF). The consortia will be used as an avenue to disseminate the results of the work, and to engage with industries with potential applications of ILLC. The organisation of a workshop on novel separation technologies for metal reprocessing, targeting both industrialists (electronic, energy and process industries) and academics will be carried out in order to maximise the impact of this work.

Presentations in conferences and publications: The exploitation of the technology and of the results will be handled through QUILL and UCL Business. In QUILL, there is a proven track record in patenting and licensing intellectual property.

Training and Investment in People:
There will be significant training of the researchers recruited in the project in the following areas:
(A) Interdisciplinary research knowledge and skills transfer between chemists and chemical engineers by researchers spending time in their collaborators' laboratories for a few weeks every year.
(B) Industrial practice and issues of technology transfer by the close involvement with both AECS and QUILL member companies who will train researchers in industrial practice and on issues of developing new technologies that can be taken up by industry.
(C) Communication skills and career development through participation in conferences and meetings and writing of research publications and project reports. Both Universities run substantial programmes on career development of researchers.

Society
Current separations of metals and spent nuclear fuel use organic mixtures that have high hazard ratings and low flash points. The unique properties of ionic liquids can overcome many of these problems, while the intensified ILLC will further reduce the amount of extractants and solvents required. ILLC will provide a direct means for separating metals from E-waste and spent catalysts. Their combination will result in a sustainable and environmentally friendly technology. We plan to disseminate the results of the project to the wider public through activities such as:

(A) Articles in general publications: Articles that discuss the importance of intensified separation technologies, of ionic liquids and of their application to treating E-waste and spent nuclear fuel will be posted on the Universities web sites and in publications with wider readership (e.g. New Scientist).
(B) Public and young people engagement activities: In the Departments we run day-courses for school children that promote the role of science and engineering in solving societal problems. In these events we will illustrate the importance of green solvents and of intensified technologies for sustainable energy and process industries and raise awareness on the general issues of E-waste and of nuclear power.