METHOD FOR SEPARATION OF ADJACENT LANTHANIDE ELEMENTS

Lanthanide complexing molecules having the following structure:wherein: R1, R2, R4, and R5 are independently selected from hydrogen atom, alkyl groups containing 1-3 carbon atoms, and hydrophilic groups containing at least one oxygen atom; R3 and R6 are independently selected from hydrogen atom, alkyl groups containing 1-3 carbon atoms, and hydrophilic groups containing at least one oxygen atom; and Ra and Rb are independently selected from hydrogen atom, methyl group, halogen atoms, and hydrophilic groups containing at least one oxygen atom; wherein at least two of R1, R2, R3, R4, R5, R6, Ra, and Rb are said hydrophilic groups. Also described is a method of separating adjacent lanthanides by use of a two-phase extractant system that includes (i) an acidic aqueous solution containing the lanthanide complexing molecule (1) along with a mixture of at least two lanthanides, and (ii) an aqueous-insoluble hydrophobic solution containing a lipophilic lanthanide extractant compound.