Thermal sintering of spent clinoptilolite zeolite for stabilization of Cs radionuclide in radioactive waste

The current study involves preparing and characterizing Iranian natural zeolite clinoptilolite from the Sabzevar region for radioactive cesium stabilization. For this purpose, cesium-loaded spent clinoptilolite zeolite was prepared, and its stabilization potential was evaluated by thermal treatment at 60, 300, 600, 900, and 1100 °C, followed by leaching tests. The findings indicate that the thermal treatment effectively stabilizes the cesium in the zeolite matrix. After thermal treatment between 60 and 1100 °C, the zeolite showed effective cesium retention during using back-exchange tests with various eluents. According to the study, when the temperature of the thermal treatment process increases from 60 to 1100°C, cesium release decreased from 98.3% to 0.23% using 1 M NaCl as the eluent. Testing with actual radioactive wastewater confirmed the successful performance of the Iranian natural clinoptilolite zeolite in adsorption and secure stabilization of Cs-137 from radioactive wastewater.