Study on highly efficient separation of zirconium from scandium with TODGA-modified macroporous silica-polymer based resin

As the similar properties of Sc and Zr, their mutual separation is difficult and Zr is one of the main impurity elements in high purity Sc2O3 which should be strictly controlled. A novel porous functionalized extraction resin TODGA/SiO2-P was synthesized for selective separation of Zr(IV) from Sc(III). The morphology and structure of the resin were profiled by SEM-EDS, BET and TG-DSC. The results of batch experiments showed that the resin had a better affinity for Zr(IV) than Sc(III) with SFZr/Sc of 25 in 6 M HNO3. Excellent separation of Sc(III) and Zr(IV) can be achieved by chromatography column experiment that more than 99% of Zr(IV) could be removed from the Sc2O3 leaching solution. The results show TODGA/SiO2-P has significant potential for separation of Zr from Sc to produce high purity scandium. In addition, the metal cation binding to the ether-oxygen and amide bonds on the ligand was revealed by FT-IR, XPS, NMR and DFT calculation. The binding of each metal cation to three TODGA ligands was determined by liquid-liquid extraction experiments. The trefoi-shaped ion clusters formed with metal ions and nitrate during extraction using diglycolamide ligands were proved by DFT simulation, which provided a new insight for the ligand chemistry of Sc and Zr.