Computational modeling of platinum recovery.

The increased value of platinum has led to intensified efforts to recover this precious metal from effluent streams.  The streams usually contain large amounts of other metals that are not wanted (such as iron) and one therefore needs to selectively recover the platinum.  Although a lot of progress has been made experimentally, where amine-substituted activated carbon (AC) is used to recover the platinum, little is known about the molecular-level mechanism of the adsorption of platinum onto the functionalised AC.  Increased knowledge at the molecular level will assist in identifying new methods for selective adsorption, as well as improving existing methods.

In these studies we model the AC carbon by attaching oxy-functional groups on graphitic structures (oxygen containing functional groups are known to exist on the AC).  The interaction between the amine groups and the functionalise AC is then studied, to ascertain which functional groups are most likely to be important for the adsorption of the amine groups.  These studies are performed at neutral pH to accurately reflect the experimental conditions.  The adsorption properties of the platinum complex ions and the adsorbed amine groups are then studied in order to understand the chemistry of the platinum adsorption.

The figure below shows the system containing the Pt complex, amine group and the carboxylic functional group.

This research, which is performed in close collaboration with the experimental studies at Tswane University of Technology, South Africa, is funded by SIDA (Swedish International Development Cooperation Agency).