An excellent example of collaboration between Chemists and Chemical Engineers has been our longstanding collaboration with Dr Ed Lester in the synthesis of metal oxide nanoparticles in high temperature water.
This area was pioneered by Professor Tad Adschiri and colleagues in Japan. The chemistry is very simple. At high temperatures, aqueous solutions of metal salts rapidly hydrolyse to form nanoparticulate oxides. Our first innovation was to show that mixtures of metal salts could be hydrolysed to give mixed metal oxides, see for example: “Continuous Hydrothermal Synthesis of Inorganic Materials in a Near-Critical Water Flow Reactor; The One Step Synthesis of Nano-Particulate Ce1-xZrxO2 (x = 0 - 1) Solid Solutions” (A. Cabañas. J. A. Darr, E. Lester and M. Poliakoff) J. Mater. Chem. (2001), 11, 561-68.
The key feature of such reactions is the way in which supercritical water and the salt solution are mixed. The major Nottingham innovation has been the invention of a “Nozzle Reactor” which exploits the relative densities of the fluids to achieve efficient mixing
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“Reaction Engineering: The Supercritical Water Hydrothermal Synthesis of Nano-Particles” (E. Lester, P. Blood, J. Denyer, D. Giddings, B. Azzopardi, and M. Poliakoff) J. Supercrit. Fluids (2006) 37, 209-214
"Synthesis of nanoparticulate yttrium aluminum garnet in supercritical water–ethanol mixtures"(A. Cabañas J. Li, P. Blood, T. Chudoba, W. Lojkowski, M. Poliakoff and E. Lester) J. Supercrit. Fluids (2007), 40, 284-292
The research has been supported by EPSRC, ICI plc and the University of Nottingham.
We always welcome e- mails to edward.lester@nottingham.ac.uk or martyn.poliakoff@nottingham.ac.uk from those interested in this area or who would like reprints of papers.
A company, Promethean Particles has now been formed to carry this technology forward.