Chemistry Weekly Seminar - Braeden Dessert, PhD Candidate, University of Saskatchewan
Braeden Dessert, PhD Candidate in the Department of Chemistry, University of Saskatchewan, will present a seminar at 1:30 pm via Zoom.
Topic:
Development of Novel Dithiobiuret Ligands for Coordination and Selective Extraction of Precious Metals
Gold, silver, platinum, and palladium have long been coveted for their lustrous appearance and economic value. In recent decades, this desirability has expanded due to their utility in various industries. This has caused a commensurate increase in demand for these precious metals, with that for gold alone reaching 3600 tonnes in 2021. Thus, there is incentive to improve methods for precious metal recovery from both primary (ore) and secondary sources (recycling). Solvent extraction methods have shown great potential in this regard, but most are limited by a lack of selectivity or environmentally hazardous solvents. Therefore, it is the goal of this research to develop novel extractants that are both selective for precious metals and usable in more economically and environmentally feasible solvents.
The Foley group has previously investigated a series of extractants known as dithiobiurets (DTBs): sulfur-based ligands reminiscent of two thiourea derivatives joined together. These DTBs are easily synthesized and have been shown to effectively coordinate to and selectively extract gold over other base metals. This talk will expand on these initial results by presenting a series of novel dithiobiuret derivatives with varied structural and physical properties, including increased solubility in non-chlorinated solvents. Coordination to precious metals is then explored, with different binding modes being observed for each of gold, palladium, and silver. The efficacy of these ligands within solvent extraction systems is then demonstrated, with some capable of extracting more than 99% of gold while maintaining selectivity. Various solvent extraction conditions will be discussed, including those with non-chlorinated organic solvents as well as some with no organic solvent at all. Overall, dithiobiuret ligands will be shown as efficient, effective extractants for precious metals.
Date: Friday, February 11
Time: 1:30 pm
Zoom link available by request to chem.dept@usask.ca