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
a:2:{s:4:"TEXT";s:190:"1Institute of Chemistry and Chemical Technology SB RAS FRC “Krasnoyarsk Science Center SB RAS”, Krasnoyarsk, Russia
2Siberian Federal University, Krasnoyarsk, Russia";s:4:"TYPE";s:4:"html";}
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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