Immobilization of radioactive cesium in fly ash using nano-sized metallic coating dispersing

2014 Fiscal Year Final Research Report

• Project/Area Number: 25550058
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Environmental engineering and reduction of environmental burden
• Research Institution: Prefectural University of Hiroshima
• Principal Investigator: MITOMA Yoshiharu 県立広島大学, 生命環境学部, 准教授 (20301674)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: 環境材料 / 廃棄物処理 / 焼却灰 / セシウム / ナノカルシウム / 放射性物質

Outline of Final Research Achievements

In this work, the capability of nanometallic Ca/CaO methanol suspension in removing and /or immobilizing stable cesium (133Cs) and radioactive cesium species (134Cs and 137Cs) in contaminated fly ash was investigated. After a first methanol and second water washing yielded only 45% of 133Cs removal. While, after a first methanol washing, second solvent with nanometallic calcium Ca/CaO methanol suspension yielded simultaneous enhanced removal and immobilization about 99% of 133Cs. SEM-EDS analysis revealed that the mass percent of detectable 133Cs on the fly ash surface recorded a 100% decrease. When real radioactive Cs contaminated fly ash (containing the initial 14,040 Bq/kg 134Cs and 137Cs cumulated concentration) obtained from burning waste from Fukushima were reduced to 3,583 Bq/kg after the treatment with nanometallic Ca/CaO methanol suspension. Elution test conducted on the treated fly ash gave 100 Bq/L total 134Cs and 137Csconcentration in eluted solution.

Free Research Field

環境化学