Solvent extraction of rare earths using a bifunctional ionic liquid. Part 1: Interaction with acidic solutions

Abstract

Bifunctional ionic liquid extractants have been examined in recent years for the separation of rare earth elements by solvent extraction. One such extractant is the quaternary ammonium phosphonate ionic liquid ‘R4N+EHEHP−’ formed from Aliquat 336 (trioctyl/decylmethylammonium chloride) and EHEHPA (2-ethylhexyl phosphonic acid 2-ethylhexyl ester, also known as P507 or PC88A). In this work, the uptake of hydrochloric acid by R4N+ EHEHP− is investigated, by studying the effect of pH, chloride, diluent and extractant concentration and composition on the extraction of acid. A fundamental understanding of the interactions between R4N+ EHEHP− and acid is considered crucial in order to describe the ..