Extraction of Yttrium-Subgroup Rare Earth Elements with Aliquat 336

The extraction of rare earth metals with Aliquat 336 technical extractant (an ionic liquid based on a quaternary ammonium salt, trioctylmethylammonium chloride) was studied. The extractant was taken in the chloride and thiocyanate forms. The extractant in the thiocyanate form extracts rare earth metals more efficiently. The lutetium distribution in extraction with 1 M trioctylmethylammonium thiocyanate from chloride-thiocyanate solutions was studied. The extraction of lanthanides (with lutetium as example) is described by the equation Lu3+ + 3NCS(-) + 3[RRMODIFIER LETTER PRIME3N]+NCS- = {(R3RMODIFIER LETTER PRIMEN)(3)(+)center dot[Lu(NCS)(6)](3)(-)}(org). Aqueous solutions of Lu3+ thiocyanates with different lutetium concentrations were studied by IR spectroscopy. A conclusion was made that the NCS- ion coordinates to the lutetium ion via nitrogen atom irrespective of the lutetium concentration. The distribution ratios were determined, and the separation factors in the extraction of rare earth metals with trioctylmethylammonium thiocyanate were calculated. The extraction and separation of rare earth metals are more efficient for the heavy lanthanides. Yttrium behaves under these conditions similarly to middle lanthanides. The 2 M trioctylmethylammonium thiocyanate-LnCl(3)-NH4NCS-H2O extraction system was concluded to be suitable for the recovery and separation of yttrium-subgroup rare earth elements.