Complexation Study of Pu(III)-Isosaccharinate Using Absorption Spectroscopy and Density Functional Theory...

Area of Science:

• Nuclear Chemistry
• Environmental Chemistry
• Radiochemistry

Background:

• Plutonium exhibits complex aqueous chemistry due to multiple oxidation states.
• Isosaccharinic acid (ISA), a cellulose degradation product, forms stable complexes with actinides, influencing radionuclide mobility.
• Understanding plutonium-ligand interactions is vital for nuclear waste management.

Purpose of the Study:

• To determine the formation constant of the plutonium(III)-isosaccharinic acid (PuISA²⁺) species.
• To elucidate the coordination structure of the PuISA²⁺ complex.
• To enhance understanding of plutonium chemical behavior in radioactive waste disposal systems.

Main Methods:

• Absorption spectroscopy was used to record spectra of Pu(III)-ISA complexes.
• Principal component analysis and derivative spectroscopy were employed for data analysis and background correction.
• Density functional theory (DFT) calculations explored the complex's coordination structure.

Main Results:

• The formation constant for the PuISA²⁺ species was determined as log β₁' = 2.38 ± 0.07.
• Spectroscopic data provided insights into the complex's spectral characteristics.
• DFT calculations suggested a tridentate coordination involving one carboxyl and two hydroxyl groups.

Conclusions:

• The determined formation constant provides quantitative data on Pu-ISA complexation.
• The study enhances the understanding of plutonium's chemical behavior in alkaline environments relevant to waste disposal.
• This research contributes to predicting and managing plutonium mobility in nuclear waste repositories.