Adsorption of DY using Synergist Extractants using Ionic Liquid Immobilised on Resins

Abstract

In the past few years, solid liquid extraction (SLE) has shown greater potential in extraction of rare earth elements (REE) compared to liquid-liquid extraction (LLE). The objective of this study is to analyse the extraction behaviour of dysprosium (Dy) using the extractant immobilised resin (EIR) in SLE. In this study, the synergist activity between ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C2mim][NTf2]) or 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2])) with conventional extractant of Aliquat 336 (A336) were investigated and the most effective synergist extractant (SE) was further immobilised onto resins (CR11, HP20 and SP207) to synthesise EIR. Inductively coupled plasma mass spectrometry (ICP-MS) was used to detect the concentration Dy before and after extraction. Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) were used to characterise EIRs. From the study, [C2mim][NTf2] showed better compatibility with A336 since this SE (A336- [C2mim][NTf2]) gives higher extraction efficiency of Dy at 90% compared to A336- [C4mim][NTf2] with less than 11% efficiency. SLE using resins immobilised with A336- [C2mim][NTf2] proved that only EIR1 (CR11) can effectively extract Dy compared to EIR2 (HP20) and EIR3 (SP207). The porosity of CR11 was higher compared to other resins which made EIR1 very efficient in adsorbing Dy. Plus, using 0.1 g of EIR1, 100% of Dy was extracted from 5 mL of aqueous phase in SLE compared to 2 mL of aqueous phase in LLE. Conclusively, this research has the potential to improvise the conventional practise of LLE into SLE using EIR with reduction in the use of extractant.