PURIFICATION OF WATER CONTAMINATED WITH RADIOACTIVE IODINE USING NATURAL AND MODIFIED ZEOLITE

The study evaluated the performance of natural zeolite and its modified forms for removing the stable iodine isotope (^127I) from aqueous solutions. The natural zeolite was modified with silver (Ag⁺) and copper (Cu²⁺) ions via an ion-exchange method. The structure and chemical composition of the modified samples were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDX).
Kinetic experiments showed that the Cu-modified zeolite reached sorption equilibrium faster than its Ag-modified counterpart. The time to equilibrium was approximately 30.5 h for the Cu-modified zeolite and about 36.0 h for the Ag-modified sample. In both cases, iodine removal from aqueous solutions was high: 99.4% for the Cu-modified zeolite and 99.1% for the Ag-modified zeolite.
Analysis of the adsorption isotherms indicated that the data were best described by the Langmuir model, with a coefficient of determination R² > 0.98. The calculated maximum sorption capacity of the modified zeolites exceeded that of the natural zeolite.
These results confirm that metal-modified zeolites are highly effective and environmentally safe sorbents for the removal of iodine-containing contaminants from water. Of particular practical interest is the Cu modification, which exhibits improved sorption kinetics and is therefore promising for water treatment technologies.

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