Washing treatment of anionic toxic element contaminated soil based on chelating reaction at mineral surface

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K20477
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 64020:Environmental load reduction and remediation-related
• Research Institution: Ibaraki National College of Technology
• Principal Investigator: Sawai Hikaru 茨城工業高等専門学校, 国際創造工学科, 助教 (30784962)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 汚染土壌 / ヒ素 / フッ素 / キレート剤 / キレート洗浄

Outline of Final Research Achievements

In the present study, the interaction among soil minerals-chelate reagent-anionic toxic components was partially clarified and the optimal decontamination process for anionic toxic components bearing soil was explored. Anionic toxic components such as arsenate and fluoride were released into the solution phase from the soil surface accompanied by the dissolving of carbonate and iron (hydro)oxide, but re-absorption occurred due to the mineral surface was covered by a positive charge, especially in the acidic solution. On the other hand, under basic conditions or in the presence of a chelate agent with small complexation constants with metal ions, the surface complexes formed by these agents negatively increase the charge on the mineral surface and prevent reabsorption of arsenate and fluoride, resulting in advantageous cleaning and removal.

Free Research Field

分析化学

Academic Significance and Societal Importance of the Research Achievements

本研究では，土壌環境基準の不適合が著しく多いヒ素，フッ素等の陰イオン性有害成分による土壌汚染リスクを根本的に解消する手法としてキレート洗浄を検討した。土壌中でキレート洗浄によって取り除かれやすい形態のヒ素，フッ素を特定するとともに，キレート剤水溶液中のヒ酸イオン，フッ化物イオンの吸脱着挙動を明らかにし，得られた成果を最適な洗浄条件の決定にフィードバックすることができた。本研究の成果は，発生量が膨大な自然由来陰イオン性有害成分による土壌汚染に対して，より効果的な洗浄処理プロセスの開発に繋がると期待される。