Development of a process for the removal and condensation of cesium from radiation contaminated soil

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K20058
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Environmental conservation measure and related fields
• Research Institution: Tohoku University
• Principal Investigator: Yoshioka Toshiaki 東北大学, 環境科学研究科, 教授 (30241532)
• Project Period (FY): 2017-06-30 – 2020-03-31
• Keywords: セシウム / 脱着 / テトラフェニルほう酸ナトリウム / イオン会合体

Outline of Final Research Achievements

The nuclear accident following the Great East Japan Earthquake in 2011 contaminated an enormous amount of soil owing to the 137Cs emitted from the nuclear plant. To resolve this problem, this study developed a method for desorbing the Cs+ strongly adsorbed in the soil using a complexing substance and then concentrating it as an ion-aggregate phase. To demonstrate this method, mordenite and A-type zeolite were selected as Cs+ adsorption minerals, and the results of an adsorption investigation revealed that these minerals, along with sodium tetraphenylborate (NaTPB) and sodium tetrakis(4-fluorophenyl) borate hydrate (NaTFPB), resulted in significant Cs+ desorption. We also elucidated the desorption reaction mechanism. Furthermore, we investigated a method for trapping the desorbed Cs+ in an aqueous phase and concentrating it to form an ion-aggregate phase. These findings have the potential to significantly contribute to reducing the volume of contaminated soil.

Free Research Field

環境プロセス工学

Academic Significance and Societal Importance of the Research Achievements

研究代表者らは水溶液中のCs+を除去・濃縮する手法の有効性について報告しているが、汚染土壌に吸着された金属イオンを脱着しイオン会合体相へと濃縮する手法は確立されていない。本研究はCs+を吸着した土壌の減容化を目指し、水系からではなく土壌からCs+を脱着、その後イオン会合体相へと濃縮可能とする手法を開発するものである。本手法の着想には、今まで前例のない土壌から対象の金属を脱着、イオン会合体相へ濃縮するという学術的な視点と、本プロセスの実用化により汚染土壌の減容化を実現するという実践的な視点の２つを含んでおり、本研究成果は学術的にも社会的にも大きな意義を有する。