The separation and isolation of metals using polyurethane materials

• Main Author: Oleschuk, Richard David
• Format: Others
• Language: en; en_US
• Published: 2007
• Online Access: http://hdl.handle.net/1993/1503

Membranes made of polyurethane have shown the ability to quantitatively extract and transport certain metal complexes from one solution to another. The transport of the metals can be controlled using appropriate solution conditions to form the extractable metal species. Initial studies performed using iron as a probe suggested that the HFeCl$\sb4$, and HFeBr$\sb4$ complexes are responsible for the extraction and transport processes. Analogous to iron, gold forms the HAuCl$\sb4$ and HAuBr$\sb4$ complexes that are both quantitatively extracted and transported through the membrane. Several separations of gold from binary metal mixtures and gold ore have been performed with complete and quantitative separation of gold from the other metals. There are several factors that effect the rate of the separation including: membrane thickness; the temperature of the system; the type of metal complex; and the concentration of the extractable metal complex in solution. A detailed study was performed on the membrane to elucidate its chemical structure and characterize degradation taking place throughout a separation experiment. Using a porous fluorocarbon filter impregnated with polytetramethylene glycol (polyTHF), we have found that gold, platinum and palladium can be extracted as the HAuBr$\sb4$, H$\sb2$PtSCN$\sb6$, $\rm H\sb2PdSCN\sb4$ complexes respectively from solution and isolated from other metals. This extraction has been shown to be dependant on the solution flow rate, filter pore size, filter porosity and the concentration of the metal complex in solution.