Separation of Group IIIB Elements from Liquid Media
The Group IIIB elements of scandium, yttrium, and lutetium readily lose their three outer shell electrons to form +3 ions in solution. The aqueous ions of M3+ are hydrolyzed in water to the common form of [M(OH)(H2O)n-1]2+. The Lanthanide series also forms these same ions so they exhibit similar separation chemistries.
Scandium and yttrium are generally present as cations, so a strong acid cation resin is the separation media of choice. Sc and Y have a high affinity for a strong acid cation resin under dilute acid conditions. The affinity diminishes at about 4 M HCl, then increases again as acid concentration increases above 4 M.
Often these metals are being separated from other closely associated metals so resins with the maximum number of theoretical separation plates are needed. Strong acid cation fine mesh resins like DOWEX™ 50WX8 100-200 Resin or DOWEX 50WX4 100-200 Resin are proposed for this separation.