Microsphere Sorbents Based on Cenosphere Supported Zirconium Molybdates and Zirconium Silicates for Cesium-137 and Strontium-90 Removal from Radioactive Waste Solutions

The microsphere composites were prepared by covering microsphere glass-crystalline supports with as-synthesized crystalline zirconium molybdate (Mo/Zr = 1.7) and pre-synthesized microporous sodium zirconium silicates of hilairite and gaidonnayite structural types. Narrow fractions of coal fly ash cenospheres with (SiO2/Al2O3)(wt) of 2.7 and 3.0 were used as precursors of the supports. The composites were studied by means of SEM, EDX and PXRD. The efficiency for Cs+ and Sr2+ removal from simulated wastewater was evaluated on the basis of parameters, such as the distribution coefficient K-d (for low Cs+/Sr2+ concentrations) and the maximum sorption capacity alpha m (for high Cs+/Sr2+ concentrations) determined from the Langmuir sorption isotherms. It was established that the composites trap Cs+ and Sr2+ with K-d of up to 10(4) mL/g. The influence of zirconium molybdate and sodium zirconium silicate composition and structure on their sorption abilities was demonstrated. The proposed resource-saving approach to the preparation of composite sorbents along with their high sorption parameters favours their application for decontamination of Cs-137 and Sr-90 bearing wastewater including aquatic environment and technological solutions.

Automated summary

The study prepared microsphere composites by coating synthesized crystalline zirconium molybdate and pre-synthesized microporous sodium zirconium silicates on microsphere glass-crystalline supports for Cs+ and Sr2+ removal from wastewater. The composites demonstrated high sorption efficiency for Cs+ and Sr2+, making them effective for decontamination purposes.