A UK first for supercritical fluid extraction

Citation

Bean, J. (1998), "A UK first for supercritical fluid extraction", Pigment & Resin Technology, Vol. 27 No. 4. https://doi.org/10.1108/prt.1998.12927daa.004

A UK first for supercritical fluid extraction

A UK first for supercritical fluid extraction

A breakthrough in supercritical fluid extraction capability has been announced by Express Separations Ltd, a University of Leeds "spin-off" company. It is the first UK company to offer the complete range of extraction facilities, from initial laboratory scale trials through to plant scale production.

Above their critical temperature, single substances do not condense or evaporate, but exist as fluids. These fluids possess unique properties intermediate in value between those of typical gases and liquids and can be controlled by temperature and pressure to obtain a wide range of extraction, reaction, separation and analytical chemistry applications. The term "supercritical fluids" was coined to describe these media, and in recent years these have been widely exploited in many industries including coatings and metals processing.

"Supercritical techniques are increasingly being applied to new large scale industrial processes, such as the production of powder coatings and structural polymers by the Ferro Corporation in the USA", says Professor Tony Clifford, technical director of Express Separations. "This has combined with the diversification of large engineering companies formerly heavily involved in the production of high pressure systems in petroleum and defence industries to reduce the capital cost of large scale SF equipment."

Express Separations (Tel:+44 (0)113 233 6529) has been instrumental in the development of supercritical fluid techniques capable of removing metals from a variety of matrices through intermediary complex formation. This route enables several applications to be successfully accomplished, such as the separation of metals from ores or tailings and the removal of heavy metals from contaminated soil.

Most supercritical fluid applications use carbon dioxide because it provides cleaner extracts than other possible solvents and in addition leaves no trace contamination in the residue. Conventional extraction techniques use organic solvents that not only contaminate the extract, but are themselves a major environmental hazard. The carbon dioxide used in supercritical fluid extraction is obtained as a by-product from fermentation and ammonia synthesis and does not add to the greenhouse effect. Furthermore, carbon dioxide is not broken down by radioactivity ­ a fact that has earned Express Separations a collaborative contract with with BNFL, researching the possibility of decontaminating radioactive material.

John Bean