Extraction mechanism of rare earths from chloride acidic solution with ammonium-bifunctionalized ionic liquid extractants

Abstract

A series of ammonium-bifunctionalized ionic liquid extractants (ammonium-Bif-ILEs) combined with a number of anions, including carboxylic acids and 1,3-diketonates, have been prepared and studied in this report. Their extraction behavior and properties toward rare earth ions (REs(III)) are systematically investigated in chloride media as a function of important parameters such as aqueous phase pH, salting-out agent concentrations, and extraction temperature. The separation performance of ammonium-Bif-ILEs toward REs(III) are systematically discussed. The results demonstrate that ammonium-Bif-ILEs have a synergistic effect between the cation and anions in separation of REs(III). The influences of different anions on separation factor (β) values are further studied. By comparison, ammonium-Bif-ILEs containing 1,3-diketonates have more potential applications in La(III)/RE(III) separation than those containing carboxylic acids.