Selective Extraction of Precious Metal Ions with Novel Trident Molecules Containing Pyridyl Groups

Abstract

Trident molecules containing pyridyl groups have been prepared for use as novel extraction reagents to investigate their physicochemical properties for dissolution into the aqueous phase and their ability, together with their corresponding monomeric analogues, to extract precious metal ions. Differences in their behavior were related to the pK _a values of the trident molecules and the position of the nitrogen atom in the pyridyl groups. The trident molecules exhibit the ability to selectively extract silver from mixtures of other precious metals. The extraction mechanism and the coordination site of the silver ion with a 2-pyridyl derivative were determined by slope analysis and peak shift of the ¹H-NMR spectra of the extraction reagent before and after silver loading.

Keywords:

• ¹H-NMR spectra
• precious metal ions
• solvent extraction
• trident molecule

ACKNOWLEDGEMENTS

The authors acknowledge Dr. Catherine Branger, Universite SUD Toulon-Var-ISITV, for her work to denominate “trident” compounds to alkyltrimethylols. This work was financially supported in part by a Grant-in-Aid for Scientific Research No. 22560815 from the Ministry of Education, Science, and Culture.