Innovation of Novel Adsorbents Derived from Geomimetics for Burying Radionuclides

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H02435
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Earth system and resources engineering
• Research Institution: Kyushu University
• Principal Investigator: Sasaki Keiko 九州大学, 工学研究院, 教授 (30311525)
• Co-Investigator(Kenkyū-buntansha): 出光 一哉 九州大学, 工学研究院, 教授 (10221079) ; 三木 一 九州大学, 工学研究院, 准教授 (10706386) ; 平島 剛 九州大学, 工学研究院, 教授 (00175556)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 放射性核種 / ジオミメティクス / 吸着 / 共沈 / 固化

Outline of Final Research Achievements

Immobilizing matrix for anionic radionuclides were investigated because these ions are mobile and in long half-life. Selenate and selenite were stabilized in hydrocalumite and ettringite. Selenite showed the greater distribution efficiencies than selenite on ettringite. There is a contrast: inner-sphere coordination of the former ions to Ca atoms and outer-sphere coordination of the later to Ca ions in ettringite. The phase transformation from hydrocalumite into ettringite was observed dependently on anionic species. Iodate was well immobilized in ettringite and hydroxyapatite immobilized iodate but not iodide, although both ions have the same charge. Ion-exchange on tertiary ammonium group bearing-surfactant modified clays is only one way to immobilize iodide as well as perrhenate which is used as a surrogate to pertechnetate. Affinity of these anions with the matrix depends on not only ionic sizes and charges but also hydrophilicity.

Free Research Field

環境材料

Academic Significance and Societal Importance of the Research Achievements

本研究の成果により、代表的陰イオン性放射性核種ごとの安定なマトリックスが明らかとなり、それを決定するのは、イオンサイズや価数だけではなく、イオンの水分子との親和性が重要なファクターとなっていることを示した。これらの成果は、核種埋設に向けてセメント系固化体にするときのポゾラン反応の過程におけるこれら陰イオン性核種の挙動を予測する上で重要な知見となる。