Synergistic Extraction of Rhodium(III) from Hydrochloric Acid Solution with Tri-n-octylamine and Sulfide-type Extractants

Abstract

Synergistic extraction of Rh(III) from relatively concentrated HCl solution was studied using two mixed solvents (di-n-hexyl sulfide (DHS)–tri-n-octylamine (TOA) and N,N′-dimethyl-N,N′-di-n-octyl-thiodiglycolamide (TDGA)–TOA) in chloroform. The Rh(III) extraction efficiency is poor when 0.5 M TOA, DHS, or TDGA is used independently. In contrast, the 0.5 M TDGA–0.5 M TOA and 0.5 M DHS–0.5 M TOA mixed solvents extract ˜90% and ˜70% of Rh(III), respectively, at maximum. Slope analyses and Job’s plots for the distribution ratios of Rh(III) at 2 M HCl show that the apparent stoichiometry of Rh(III):TOA:(DHS or TDGA) in the extracted complex is 1:2:1.

Keywords:

• rhodium
• synergistic effect
• tri-n-octylamine
• thiodiglycolamide
• di-n-hexyl sulfide

Additional information

Funding

A part of this study was financially supported by JSPS KAKENHI Grant Numbers 23360407 and 26289283.