Influence of the structure of tetradentate phosphonate esters on stability constants of their complexes with f-elements (La, Nd, Eu, Lu и Th)

Abstract

One of the approaches for solving the global energy crisis is nuclear energy. Nuclear energy is considered now as a sustainable green source of energy. The main advantages of which are high energy intensity and low levels of greenhouse gas emissions. Its disadvantages include the possibility of radioactive contamination and the problem of radioactive waste storage. Thorium fuel is receiving increasing attention due to the continued consumption of uranium resources, since 232Th can be converted to 233U by absorbing slow neutrons. Extraction and separation of lanthanides and thorium is necessary both for isolation of thorium from ore sources and the disposal of high-level wastes. To study the extraction separation of thorium and lanthanides, we need knowledge of the stability constants of f-elements.
In this work, the effect of complexation between hydrates of metal nitrates (M: La3+, Nd3+, Eu3+, Lu3+ and Th4+) and organic reagents based on [2,2'-bipyridine]-6,6'-diylbis(phosphonate) and 1,10-phenanthroline-2,9-diylbis(phosphonate) was studied by spectrophotometric titration on a Hitachi U-1900 spectrophotometer at a constant temperature of 25°C. It was found that for all metal-ligand pairs in the solution, only one complex particle of the metal-ligand composition 1:1 is present in acetonitrile (with a water content of 40±5 ppm). The stability constants of complexes with f-elements were determined by spectrophotometric titration. The results were processed using the HypSpec2014 program.
This work was supported by RSF, grant No. 21-73-20138.

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Tsagana Sumyanova
Lomonosov Moscow State University
Russia

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