Characterization of soluble and insoluble radioactive cesium in municipal solid waste incineration fly ash

• Published in: Chemosphere (Oxford) 2020-06, Vol.248, p.126007-126007, Article 126007
• Main Authors: Ohbuchi, Atsushi, Fujii, Kengo, Kasari, Miki, Koike, Yuya
• Format: Article
• Language: English
• Subjects: Carbon; Cesium - chemistry; Cesium Radioisotopes - analysis; Chemical treatment; Chlorides; Coal Ash - chemistry; Heating treatment; Incineration; Metals, Heavy - analysis; Municipal solid waste incineration fly ash; Radiation Monitoring; Radioactive Pollutants - analysis; Radioactivity; Refuse Disposal - methods; Silicates; Solid Waste - analysis; Soluble and insoluble radioactive cesium; Tessier extraction method; X-Ray Diffraction
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.126007

Soluble and insoluble radioactive cesium in municipal solid waste incineration fly ash were analyzed by X-ray diffraction and gamma-ray spectrometry. A total of 60% of soluble radioactive cesium was determined using the Tessier extraction method, and it was almost same extraction rate with Japanese leaching test No.13. In addition, chloride compounds such as halite (NaCl) and sylvite (KCl) showed same behavior with soluble radioactive cesium, therefore, soluble radioactive cesium existed as a chloride (CsCl) with water solubility characteristics. Almost insoluble radioactive cesium trapped into silicate of crystalline phase or amorphous phase was eluted by hydrogen fluoride treatment. Radioactive 137Cs was released in three stages by heating treatment (untreated - 400 °C, 600 °C–800 °C, and 800 °C–1000 °C) according to decreasing amorphous content. The relationship between the concentrations of radioactive 137Cs and amorphous phase exhibited good linearity (R = 0.9278). Insoluble radioactive 137Cs was contained in inner part of the amorphous phase, and free radioactive cesium was determined from the concentration of the amorphous phase. •Radioactive Cs in MSWI fly ash was separated into soluble and insoluble forms.•The result of Tessier method indicated that water-soluble radioactive Cs exists as CsCl.•Insoluble radioactive Cs was trapped into silicate as amorphous phase result from chemical treatment.•Silicate-bound and free radioactive Cs were contained into surface and inner part of the silicate amorphous phase.