Insight into acidity driven third phase formation of TBP in organic solutions by MD simulation

Selective Separation of HNO3 and HCl by Extraction: The Investigation on the Noncovalent Interaction between Extractants and Acids by Density Functional Theory

There is a huge demand for the highly selective separation of HNO₃ and HCl in many industries, and solvent extraction is considered a feasible method. In this article, DFT calculations were performed to investigate the interactions between acids and extractants including alcohols, ketones, phosphorus, and amines. One of the significant findings to emerge from this study is that amines bind to acids through ion association. Nevertheless, the interaction between acids and alcohols, ketones, and phosphorus with a (RO)₃P═O structure is mainly dominated by hydrogen bonds. The change of Gibbs free energy in the extraction process shows that the phosphorus ((RO)₃P═O) is superior to other types of extractants in the selective separation of HNO₃ and HCl. Furthermore, after the alkoxyl group (RO-) in phosphorus ((RO)₃P═O) is replaced by RN- or R- with less electronegativity, the interaction between HCl and the substituted extractants transitions from a hydrogen bond to ion association, but there are still strong hydrogen bonds between them and HNO₃. That will lead to a decrease in the selectivity of phosphorus due to the change in interaction types. This new understanding should help the design and screening of efficient extractants for the separation of mineral acids.

Interference of Zr(IV) during the extraction of trivalent Nd(III) from the aqueous waste generated from metallic fuel reprocessing

A metallic alloy of uranium–zirconium and uranium–plutonium–zirconium has been proposed as a fuel for fast reactors, owing to the possibility of achieving high breeding ratio in a short span of time. About 6–10 wt.% of zirconium has been added to these actinide fuels to increase the melting temperature and thermal-mechanical stability. Aqueous reprocessing of the spent metallic fuel generates the high-level liquid waste (HLLW) that contains about 60 % of the total zirconium from the fuel. In view of this, the extraction behavior of a trivalent representative ion, Nd(III) in the presence of Zr(IV) was studied from nitric acid medium using the candidate ligands proposed for trivalent actinide separation from HLLW, such as N,N,N′N′-tetraoctyldiglycolamide (TODGA), and N,N-di-octyl-2-hydroxyacetamide (DOHyA). The extraction was studied as a function of nitric acid concentration, zirconium and neodymium concentration and Nd(III) to Zr(IV) ratio. The findings of dynamic light scattering (DLS) and ATR-FTIR spectral techniques were used for understanding the complex chemistry of Zr(IV) extraction under different conditions. Poor extraction of nitric acid, smaller aggregate size, no third phase formation during the extraction of Zr(IV) and Nd(III) and other unique solvent properties favor the DOHyA molecule in n-dodecane as a solvent for partitioning of trivalent actinides from HLLW generated from metallic fuel reprocessing.

Density functional theory investigations on the coordination of Pa(v) with N,N-dialkylamide

The density functional theory (DFT) method was used to study the coordination of a series of N,N-dialkylamides with Pa(v) to shed light on the inherent principles for screening amide extractants of Pa(v) from aqueous solution.

Minimizing the aggregation of diglycolamide reverse micelles in the n-dodecane phase with bis-(2-ethylhexyl)phosphoric acid “reactive” phase modifier

“Reactive“ phase modifiers enhance the extraction of trivalent metal ions through synergism and prevent third phase formation.

Network analysis and percolation transition in hydrogen bonded clusters: nitric acid and water extracted by tributyl phosphate

Network analysis of hydrogen bonded clusters formed in simulation by extraction of nitric acid and water by TBP interprets cluster topologies and identifies the mechanism for third phase formation.