An ionic liquid-based extraction system using diglycolamide functionalized macrocyclic platforms for the extraction and recovery of lanthanides.

Solvent extraction of lanthanides Ln(iii) (La, Eu and Yb) with resorcin[4]arene cavitand-triazole-DODGA (CR4-TZ-DODGA) and t-butylcalix[4]arene-triazole-DODGA (C4-TZ-DODGA) has been studied in a room temperature ionic liquid (RTIL), N-octyl-N-ethylpiperidinium bis(trifluoromethylsulfonyl)imide ([EOPip]NTf2). The two macrocyclic platforms were functionalized with four diglycolamide (DGA) moieties thanks to a click reaction and fully characterized by NMR and MS analysis. The effects of acidity as well as the concentration of the ligands were investigated on the extraction and separation properties. The parameters of the extraction processes were determined by the slope method and thermodynamic studies. For both ligands, the extraction efficiency changes along the lanthanoid series with selectivity toward Yb(iii) in regard to La(iii) and Eu(iii). The selective extraction and recovery of lanthanides from a simulated leaching solution of a Nd/Fe/B/Dy magnet has also been investigated.