Extraction Behavior of Precious Metals in Hydrochloric-acid Media Using a Novel Amine Extractant Bearing a Furan Group

Abstract

Amine extractants are effective for extracting precious metals in hydrochloric-acid media. We developed a novel secondary-amine extractant 2-ethylhexylfurfurylamine (EH-A-F). EH-A-F showed a higher Pd(II) extractability compared with many secondary-amine compounds, such as di(2-ethylhexyl)amine. Because the Pd(II) extraction from solutions of lower hydrochloric-acid concentration is small, Pd(II) and Au(III) can be extracted selectively from the trivalent metal ions Fe(III), Ga(III), and In(III). Because the extractability of hydrochloric acid using EH-A-F was lower than that of a competitive amine compound, benzyl 2ethylhexylamine, EH-A-F was found to show a higher Pd(II) extractability because of its moderate basicity. Slope analysis for Pd(II) extraction showed that the complex stoichiometry was 2:1 for EH-A-F and Pd(II). The Pd(II) extracted by using EH-A-F was stripped quantitatively by using aqueous thiourea solution.