Impact of Coordination Modes of N‐Donor Ligands on Am(III)/Eu(III) Separation in Nuclear Waste Water Treatment – A DFT Study

Abstract

Detection and degradation of environmental pollutants is always a challenging task, especially in nuclear waste management. The presence of radioactive minor actinides in the spent nuclear fuel from nuclear reactors leads to adverse effects on both humans and the environment. In this context, designing ligands plays a pivotal role in the partitioning process of actinides from lanthanides. Though we have many ligands with varying coordination modes reported, one needs to look deeper into the role and number of coordinating atoms of a ligand to gain a basic understanding of the extraction process. Hence, N‐donor ligands (Pypz, BTP, BTPhen and TPDCA) with a different number of coordinating atoms (two, three, four and five) and their Am/Eu complexes have been considered for this study. Exhaustive density functional theory calculations have been carried out to get an essence of the coordination chemistry of ML(NO3)3 complexes and how the number of coordinating atoms impacts the selectivity towards Am3+ over Eu3+ ions. The calculated thermodynamic parameters shed light on the selectivity of these ligands towards Am(III) over Eu(III). Results reveal that the BTP ligand shows the best selectivity out of all the ligands. We found that the higher the number of coordination modes higher will be the binding energy. However, the selectivity depends on the strength and nature of M−L bonds. In brief, this study offers us insights into the tailoring of ligands with an optimum number of coordinating atoms for Am(III)/Eu(III) stripping in the spent nuclear waste processing.

Preorganization of N,O-hybrid phosphine oxide chelators for effective extraction of trivalent Am/Eu ions – a computational study

“…In this work M(NO 3 ) 3 is one fragment and the ligand is another fragment, as reported in the literature. 54,57,61 These two fragments are considered to be neutral moieties for the EDA calculations in the water medium. The calculated Pauli repulsion, electrostatic interaction, orbital energy, and the total binding energy (TBE) of all the complexes are shown in Table 5.…”

“…This is in line with our earlier reports. 57,61 However, in the Eu complexes the electrostatic interactions are greater than the orbital interactions, and thus the total binding energy is chiefly from electrostatic interactions. This is as reported in earlier studies.…”

Hydrogen-Bond-Assisted Adsorption of Nitric Oxide on Various Metal-Loaded ZSM-5 Zeolites

“…50 The total binding energy (TBE) between two moieties is basically the sum of the steric interaction energy (E steric ) and the orbital contribution energy (E orb ). 50 In fact, E steric is the total of the electronic repulsion (E Pauli ) due to Pauli's principle and the stabilizing electrostatic energy (E ES ). Thus, TBE is calculated as per eq 3.…”

“…Relativistic adjustments based on Zero-Order Regular Approximation (ZORA) were employed during the EDA as encoded in ADF 2019.105 software . The generalized gradient approximation functional BP86 composed of Becke exchange and Perdew correlation functional was utilized for EDA. , The spin-unrestricted EDA is carried out assuming that spin-unrestricted fragments (NO and M-ZSM-5) form a spin-unrestricted complex . The total binding energy (TBE) between two moieties is basically the sum of the steric interaction energy ( E steric ) and the orbital contribution energy ( E orb ) .…”

“…The generalized gradient approximation functional BP86 composed of Becke exchange and Perdew correlation functional was utilized for EDA. , The spin-unrestricted EDA is carried out assuming that spin-unrestricted fragments (NO and M-ZSM-5) form a spin-unrestricted complex . The total binding energy (TBE) between two moieties is basically the sum of the steric interaction energy ( E steric ) and the orbital contribution energy ( E orb ) . In fact, E steric is the total of the electronic repulsion ( E Pauli ) due to Pauli’s principle and the stabilizing electrostatic energy ( E ES ).…”