| Summary: | Co-processing of radioactive effluents with coal fly ash-derived materials is recognized as a resource-saving approach for efficient stabilization/solidification of radioactive components of wastewater. In this context, the paper is focused on the hydrothermal synthesis of Sr<sup>2+</sup>-bearing aluminosilicate/silicate phases as analogs of a mineral-like <sup>90</sup>Sr waste form using hollow glass-crystalline aluminosilicate microspheres from coal fly ash (cenospheres) as a glassy source of Si and Al (SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub>)<sub>glass</sub>) and Sr(NO<sub>3</sub>)<sub>2</sub> solutions as <sup>90</sup>Sr simulant wastewater. The direct conversion of cenosphere glass in the Sr(NO<sub>3</sub>)<sub>2</sub>-NaOH-H<sub>2</sub>O-(SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub>)<sub>glass</sub> system as well as Sr<sup>2+</sup> sorption on cenosphere-derived analcime (ANA) in the Sr(NO<sub>3</sub>)<sub>2</sub>-H<sub>2</sub>O-ANA system were studied at 150–200 °C and autogenous pressure. The solid and liquid reaction products were characterized by SEM-EDS, PXRD, AAS and STA. In the Sr(NO<sub>3</sub>)<sub>2</sub>-NaOH-H<sub>2</sub>O-(SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub>)<sub>glass</sub> system, the hydrothermal processing at 150–200 °C removes 99.99% of the added Sr<sup>2+</sup> from the solution by forming Sr-tobermorite and Sr-plagioclase phases. In the Sr(NO<sub>3</sub>)<sub>2</sub>-H<sub>2</sub>O-ANA system, Sr<sup>2+</sup> sorption on analcime results in the formation of solid solutions (Na<sub>1−n</sub>Sr<sub>n/2</sub>)AlSi<sub>2</sub>O<sub>6</sub>·H<sub>2</sub>O of the Na-analcime–Sr-wairakite series. The results can be considered as a basis for the development of environmentally sustainable technology for <sup>90</sup>Sr removal from wastewater and immobilization in a mineral-like form by co-processing waste from coal-fired and nuclear power plants.
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