Separation of cesium and strontium from real radioactive waste solutions using a high-efficiency cobalt aluminum silico tungstate: batch and column studies

Abstract

An advanced inorganic cobalt aluminum silico tungstate (CoAlSiW) sorbent was successfully synthesized and subsequently applied for the selective elimination of radioactive cesium and strontium ions from real liquid radioactive waste streams. CoAlSiW was characterized using diverse analytical techniques to reveal its structure, surface morphology, and physicochemical features. Studies on batch adsorption were conducted to evaluate the impacts of pH, contact time, initial ion concentration, and temperature on the sorption performance. The adsorption of Cs(I) and Sr(II) follows Freundlich isotherm model, confirming heterogeneous surface characteristics and favorable multilayer sorption behavior. According to thermodynamics, the process is spontaneous and energetically favorable. Importantly, the impact of gamma irradiation was evaluated, confirming the material’s high radiation stability and resistance, with no significant loss of sorption efficiency. Dynamic column breakthrough experiments further highlighted high sorption capacities of 78 mg g⁻¹ for Sr(II) and 72 mg g⁻¹ for Cs(I). The applicability of CoAlSiW for real radioactive waste treatment was confirmed by its high removal efficiency toward ¹³⁷Cs (92.6%) and a decontamination factor exceeding 13.3. Consequently, separation of radioactive cesium from liquid radioactive waste streams is recommended due to its significant radiological hazard, long half-life, and high mobility in the environment.