Frank Lewis is Senior Lecturer in Organic Chemistry in the Department of Applied Sciences. He is a graduate of Trinity College Dublin where he obtained his PhD in Organic Chemistry in 2008 in the group of Prof. David Grayson for his work on novel chiral sulfones. He was then appointed as a Postdoctoral Research Fellow at the University of Reading with Prof. Laurence Harwood working on the design and synthesis of actinide-selective organic ligands for spent nuclear fuel reprocessing (as part of the EU FP7-funded ACSEPT project). He joined the Department of Applied Sciences at Northumbria University as an Anniversary Research Fellow in 2012, and was appointed to his current role in 2015. His research focus is on the design, synthesis and evaluation of ligands for selective removal of targeted metal ions (specifically actinides) that are present in spent nuclear fuels.

Nuclear power is becoming an increasingly key part of the energy mix in many countries as it offers a clean, low-carbon source of energy. However, a major disadvantage of nuclear power is the long-lived and highly radioactive nature of the waste that it produces, which is due to the presence of the actinides uranium, plutonium, americium and curium in spent nuclear fuel. In the currently-used PUREX (Plutonium and Uranium Reduction Extraction) process, uranium and plutonium are removed from the aqueous spent nuclear fuel liquor by solvent extraction and recycled as mixed-oxide (MOX) fuel, but no process is currently used to remove and recycle the minor actinides americium and curium. If these elements were removed, the time taken for the radioactivity of the remaining waste to decay to the levels of natural uranium would decrease from approx. 10,000 years to a much more manageable few hundred years.

In order to recycle the minor actinides, they must first be separated from the chemically similar lanthanides that are also present in spent nuclear fuel. Thus, future processes for recycling the minor actinides require highly selective organic ligands that can discriminate between the minor actinides and lanthanides. Of the many ligands screened for carrying out this challenging separation, ligands containing 1,2,4-triazine rings (BTPs, BTBPs, BTPhens) have emerged as some of the most selective.

Research in the Lewis group is focused on fine-tuning the structures and hence extraction properties of these ligands to maximise the efficiency of any future industrial recycling process using these ligands. Current projects include the evaluation of novel hydrophobic ligands with improved solubilities and rates of metal extraction (funded by EPSRC), as well as novel hydrophilic ligands that can be used as actinide-selective aqueous complexing agents (funded by National Nuclear Laboratory under the Advanced Fuel Cycle Programme).