Solvent extraction of lanthanides with crown ethers

The process of Ln(La, Ce, Nd, Sm, Eu, Gd, Dy, Er, Yb, Lu, Y) extraction with crown ethers of different composition differing both by the macrocycle dimension and by the structure of substituents in the macrocycle is studied. Crown ethers noticeably extract lanthanides from nitric acid aqueous solutions only at the presence of high salt background in aqoeous phase at the expense of high concentrations of Ln(NO3)3 or other salts (LiNO3, NH4NO3). Crown ethers are shown fo extract Ln slightly better than linear analogs but presence of crown effect should be considered only in case of dicyclohexyl-18-crown-6. DCH18C6 has higer separatian coefficients at Ce, Dy, Eu extraction and negligibly extracts y that can be used for selective extraction of these lanthanides from mixture of rare earths. The problem of composition and structure of extracted complexes of crown ethers with Ln(NO3)3 remains to be solved