Extraction and complexation of trivalent rare earth elements with tetraalkyl diglycolamides

[Display omitted] •The extraction of DGAs towards La3+, Pr3+, Nd3+, Eu3+, Gd3+, Y3+, Er3+ and Yb3+ was systematically investigated.•The extraction thermodynamic parameters (ΔH, ΔS and ΔG) were obtained.•The complexation of DGAs with Eu3+ was explored by means of FT-IR, 1H NMR, Luminescence spectroscopic titration and microcalorimetric titration.•The complexation stability constants and thermodynamic parameters of Eu3+ with DGAs were given. The extraction and complexation behaviors of four tetraalkyl diglycolamide (TRDGA, where R represents n-butyl, n-hexyl, n-octyl and 2-ethylhexyl) ligands with linear chain or branched chain structure were described with respect to La3+, Pr3+, Nd3+; Eu3+, Gd3+; Y3+, Er3+ and Yb3+ as the representatives of light, middle and heavy rare-earth group ions in HNO3 solution. Effects of acidity, ligand concentration and temperature on the distribution ratio of these ions were examined. High acidity was good for the extraction. For same metal ion, the extractability of DGA ligands followed the order of T2EHDGA