Study on the extraction of lanthanides by a mesoporous MCM-41 silica impregnated with Cyanex 272

This work reports the synthesis of mesoporous silica impregnated by an acidic organophosphinic ligand (Cyanex 272) for the extraction of rare earth elements (REE). The prepared solid was characterized by X-ray diffraction (XRD), and N2 sorption at 77 K. The effect of pH, ligand loading, time and initial concentration on REE extraction were studied. Selectivity between light lanthanides (La), medium (Eu) and heavy lanthanides (Lu) followed the usual order Lu > Eu > La. The stoichiometry of the different species formed inside the porosity according to the conditions of the extraction (lanthanide nature and concentration; ligand loading) is proposed. The phosphinic ligand Cyanex 272 showed encouraging complexing properties in the porosity of the silica for its use in extraction and separation of rare earth metals.