Hydrothermal Synthesis of Cesium and Strontium Bearing Mineral-Like Phases Using Coal Fly Ash Cenospheres
T. A. VERESHCHAGINA1, E. A. KUTIKHINA1, E. V. MAZUROVA1, E. V. FOMENKO1, A. G. ANSHITS1,2
1Institute of Chemistry and Chemical Technology SB RAS FRC “Krasnoyarsk Science Center SB RAS”, Krasnoyarsk, Russia
2Siberian Federal University, Krasnoyarsk, Russia
Keywords: cenospheres, radioactive waste, pollucite, plagioclase, tobermorite
Pages: 269-279
Abstract
The possibility of hydrothermal synthesis of Cs and Sr bearing framework aluminosilicates in the CsNO3-NaOH-H2O-(SiO2-Al2O3)glass and Sr(NO3)2-NaOH-H2O-(SiO2-Al2O3)glass systems using coal fly ash cenospheres was studied as a low-temperature method to include the water-soluble forms of radionuclides 137Cs и 90Sr in a mineral-like form. The syntheses were carried out at temperatures in the range of 80-200 °С and autogenous pressure. Narrow fractions of cenospheres with the glass phase content of 90-95 mass % were used as aluminosilicate glass, and compounds of stable isotopes of Cs and Sr were used as imitators of radionuclides 137Cs и 90Sr. Based on the data obtained in the studies of solid products and post-synthetic solutions by means of X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray microanalysis (SEM-EDX) and atomic absorption spectroscopy (AAS), it was established that the Cs bearing analcime-pollucite solid solutions (Na n Cs1- n )AlSi2O6∙ n H2O are crystallized in the Cs-containing system at 120-150 °C with 98 % Cs+ removal from solution to the solid product. The Sr bearing phases of tobermorite and plagioclase structural types are formed in the Sr(NO3)2-NaOH-H2O-(SiO2-Al2O3)glass system. In this case, the effectiveness of Sr2+ extraction from solution is not less than 99.99 %.
DOI: 10.15372/CSD2021305
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