Chemical Engineering & Technology, Vol.41, No.9, 1697-1705, 2018
ONIOM Study for Selectivity of Extractants for Extraction of Rare-Earth Metals
A hybrid molecular modelling technique, the ONIOM method, has been used to study the selectivity of various extractants for the extraction of La3+ and Nd3+. MM calculations have been done for the environmental system, whereas DFT calculation has been carried out for the model system. The total ONIOM energy of the metal-ligand complexes was calculated and the selectivity of La3+ and Nd3+ for D2EPHA, Cyanex 272 as well as PC88A determined based on the interaction energy. The lower energy for Nd complexes compared to La complexes for all three extractants shows preference of Nd over La. The ONIOM calculations infer the stability of the metal complexes in the order of D2EPHA>PC88A>Cyanex 272, which agrees well with the experimental results for both metal ions.