Textural and structural effects of heat treatment and γ-irradiation on Cs-exchanged NaX zeolite, bentonite and their mixtures

Abstract

NaX zeolite, Algerian bentonite, their mixtures, and their Cs-exchanged forms are subjected to heat treatment at different temperatures (800, 1000, and 1100°C) and γ-irradiation doses varying from 100 to 1000kGy. The effects of these treatments on structural and textural properties of the above materials as getters of radionuclides are studied using powder X-ray diffraction (XRD), nitrogen adsorption surface analyzer, and scanning electron microscopy (SEM). A thermal treatment of NaX and CsNaX zeolites up to 1000°C results in the formation of new crystalline phases (nepheline and carnegieite). In contrast, bentonite becomes totally amorphous when it is heat treated up to 800°C. Heat treating of zeolite–bentonite mixtures gives rise to partial amorphisation. γ-Irradiation of the studied materials reveals a good resistance of the Cs exchanged NaX zeolite. This is due to its higher basic character resulting from the Cs2O formed by the reaction between Cs+ present in the zeolite and the O2− anion liberated after γ-irradiation.