Developing sustainable phytomining for the capture of nickel and palladium and production of plant-based green solvents

This highly multidisciplinary project will give the student significant opportunity to learn about various aspects of biology, environmental science and chemistry. As such, this PhD will be uniquely trained between these three departments. Nickel (Ni) and palladium (Pd) are industrially important metals used in a wide number of catalyst-based applications; however, while demand is increasing, this limited resource is being lost through dispersal and dilution into the environment.

Phytomining is an approach whereby specific metals can be extracted and re-concentrated from waste sources. In the case of Ni and Pd, waste sources include mine tailings which contain concentrations of these metals at levels uneconomic to extract using conventional methods. Key to the success of phytomining is the value of the end product. Up until now, this has been limited by the value from smelting metal-containing plant biomass. But, results at the GCCE demonstrate that the controlled pyrolysis of Ni and Pd-containing plant biomass has been shown to release value-added products, including platform molecules which a can be used in the production of solvents, that may make this process economically achievable. In collaboration with CNAP, in Biology, we have recently shown that the size of metal nanoparticles deposited in the plant tissues can be manipulated in planta to altering nanoparticle size and catalytic properties. While these results are promising, a major hurdle to the application of this new technology is that these metal wastes and soils has only limited availability to plant roots. Recent studies by Mark Hodson in Environment, have shown that earthworms can solubilise Ni. Earthworms are an important component in soil ecosystems and central to both re-vegetation and phytomining of mine wastes, and increasing evidence suggests they contribute to plant health.

This project will investigate (i) the role of earthworms on the solubilisation of Ni and Pd from metal wastes (ii) the effect of earthworms on plant health and metal uptake by plants, (iii) the effect of earthworm-enhanced metal uptake on nanoparticle formation in plant lines which have been expressed to promote development of these particles, and (iv) the effect of nanoparticle composition, shape and size on the microwave pyrolysis, model systems such as cellulose, hemicellulose and lignin will be used to both optimise and understand the mechanism of metal catalysed microwave pyrolysis. The knowledge gained from model systems will be applied metal containing biomass, this will be used to fine-tune the microwave pyrolysis-based production of plant-derived chemicals. This will commence in Arabidopsis, a model species for plant genetics, but will also include studies in miscanthus, and a willow cultivar from a screen we conducted to identify lines with high Pd uptake.

Shortlisting will take place as soon as possible after the closing date and successful applicants will be notified promptly. Shortlisted applicants will be invited for an interview to take place at the University of York on Friday 12 May. Candidates will be asked to give a short presentation prior to their interview by an academic panel. All research students follow our innovative Doctoral Training in Chemistry (iDTC): cohort-based training to support the development of scientific, transferable and employability skills
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