Highly efficient extraction separation of La3+ and Ce3+ with N, N, N′, N′-tetraisobutyl-3-oxadiglycolamide from mixed REEs

•The separation factor of La3+ and Pr3+ is as high as 133.7.•The separation factor of Ce3+ and Pr3+ is up to 136.5.•La3+ coordinates with ten oxygen donor atoms forming La(TiBDGA)2Cl3·4H2O.•A simple and efficient strategy for separating La3+ and Ce3+ from the mixed REEs. The extraction and selective separation of Ln3+ with N, N, N′, N′-tetraisobutyl-3-oxadiglycolamide (TiBDGA) from the aqueous HCl solution was studied. The extraction temperature, diluent, salting-out agent, hydrochloric acid concentration, and extractant concentration were investigated to evaluate the effect on the extraction distribution ratio. The extraction mechanism was established based on the FT-IR spectra, XPS analysis, and crystal structure, which ascertains that the stoichiometry of the complex is La(TiBDGA)2Cl3·4H2O. The complex crystallizes in the orthorhombic space group Pbca and La3+ ions coordinate with ten oxygen donor atoms. The extraction results showed that TiBDGA has good selectivity of La3+ and Ce3+ from the other Ln3+. The presence of both NaCl and HCl showed a significant enhancement of extraction and separation. When the concentrations of both HCl and NaCl solution were 2.0 M, the separation factors of La3+ and Ce3+ from adjacent Pr3+ were as high as 133.7 and 136.5, respectively.