COMPUTATIONAL STUDY ON THE INTERACTION OF SOME TRIVALENT LANTHANIDE IONS WITH TRIPROPYL PHOSPHAT LIGAND

Since the half-lives of some elements is millions of years, radiochemists have been engaged for the development of new extractants for the extraction of minor actinides and lanthanides from the high level nuclear waste. In this context, several organophosphorus as well as phosphat based extractants have been proposed and examined thoroughly for the extraction of actinides and lanthanide ions. Phosphate derivatives have been introduced as completely incinerable extractants that produce no radioactive solid waste by combustion with a good extractability. In this research, we have employed density functional theory (DFT) methods to predict the thermodynamical and electronic properties of complexation between La+3 and tripropylephosphate (TPP). In the case of La+3, we have applied the quasi-relativistic effective core potential (RECP) of stuttgart group. In the first step, the enthalpy and Gibbs free energy changes of the complexation have been calculated at M06/6-311+G** level of theory in the gas and three solution phases via PCM computations. We have shown the thermodynamical preference of using nonpolar solvents such as n-hexane for the complexation process that is in confirmation with the previously observed experiments

Keywords:

Density functional theory , Lanthanum ion , Phosphate ligands , Polarized continuum model , Thermochemical properties