Chemical modeling of platinum group metal of extraction reactions from nitric acid solution based on ligand field analysis

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K15210
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 31010:Nuclear engineering-related
• Research Institution: Osaka University (2022-2023); Japan Atomic Energy Agency (2020-2021)
• Principal Investigator: Kaneko Masashi 大阪大学, 大学院理学研究科, 講師 (50781697)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: DFT計算 / 白金族元素 / 溶媒抽出 / 計算化学

Outline of Final Research Achievements

We conducted research with the aim of simulating the solvent extraction reaction of platinum-group elements based on the prediction of the coordination structures and the complexation reactions of platinum group elements contained as fission products in high-level radioactive liquid waste, First, we benchmarked the exchange and correlation functional functionals in the DFT method using the reported Mössbauer isomer shift values of the platinum group metal complexes, and then used the results to model the complexes of Ru, Rh, and Pd ions with nitrate ions, chloride ions, and ligands, and confirmed the validity of the model by comparing them with the experimental values. Furthermore, it was found that the typology of ion associative-/coordinative- type extraction of Pd ions can be predicted by DFT calculation. A new guideline for DFT modeling of solvent extraction of platinum group elements was provided.

Free Research Field

原子力化学・アクチノイド化学

Academic Significance and Societal Importance of the Research Achievements

高レベル放射性廃液からの白金族元素回収技術の開発は、ガラス固化工程の阻害要因の低減や、有価金属としての利用に繋がる。白金族元素の溶媒抽出分離を考える場合、白金族元素の水溶液中での配位構造の違いが安定性や反応性に起因するが、構造の多様性のため、系統的な議論は困難である。本研究では、計算化学手法を用いてRu, Rh, Pdの溶媒抽出反応における錯体モデリングを行う上で、メスバウアー分光パラメータを用いたDFTベンチマークや、硝酸中における溶存状態の系統的な研究を行い、さらには、Pdにおいて配位型/イオン会合型抽出反応の予測可能性を検討した。