Application of bifunctional ionic liquids for extraction and separation of Eu3+ from chloride medium

Abstract

The extraction of Eu3+ from chloride medium using bifunctional ionic liquid extractants (Bif-ILEs) tri-n-octylmethyl ammonium bis(2-ethyl hexyl) phosphate ([A336][D2EHP]) and trihexyltetradecyl phosphonium bis(2-ethylhexyl) phosphate ([P66614][D2EHP]) in kerosene was studied to develop environmentally friendly extraction process. The extraction behavior of Eu3+ was examined by varying key process parameters. The extraction behavior indicates that ammonium-based ionic liquid [A336][D2EHP] shows better extraction efficiency of Eu3+ than that of phosphonium-based ionic liquid [P66614][D2EHP]. Quantitative extraction of Eu3+ is obtained with 0.05 mol/L [A336][D2EHP], whereas, 0.1 mol/L of [P66614][D2EHP] is required to achieve the same extraction rate of Eu3+. The extraction process is endothermic with respect to [A336][D2EHP]. Stripping experiments indicate that 100% of Eu3+ can be back extracted from both the loaded ionic liquids using 20 vol.% HNO3. The highest separation factor (βY/Eu) of 653.59 is reported at pH of 3.2, and the separation factor of Eu3+ over La3+ is 30.6 at the same pH. From the leach liquors of waste tube light powder, 99.98% of Eu and 99.99% Y are recovered using 0.2 mol/L [A336][D2EHP] in 2-stage cross current extraction with aqueous to organcic ratio (O/A) of 1:1 and 1:2.