Recovery of precious metals from spent automobile catalytic converters using supercritical carbon dioxide

Recovery of precious metals (platinum, palladium, and rhodium) from a solid matrix sample by supercritical carbon dioxide containing a chelating ligand, a tributyl phosphate (TBP), was studied. The effects of temperature, pressure, and static extraction time on the extraction efficiency were investigated. All experiments were performed using a supercritical fluid extraction system at a temperature range of 40-80 degrees C and a pressure Of Lip to 30 MPa. Results showed that addition of the chelating ligand was necessary to extract the metals. Experiments with pure supercritical carbon dioxide result in no extraction of the metals. It has been observed that the extraction efficiency of metals was strongly dependent on temperature, pressure, and static extraction time. (c) 2008 Curtin University of Technology and John Wiley & Sons, Ltd.