Comparison of Adsorption Ability of Firoozkooh and Tabriz Natural Nano-Zeolites for the Removal of Thorium and Uranium Ions from an Aqueous Solution

The separation of thorium and uranium ions in radioactive waste is one of the important and complex processes in the management and storage of radioactive waste in the nuclear industry. One way of removing radioactive materials from nuclear waste is by means of natural adsorbents. In this study, natural zeolites of Firoozkooh and Tabrizhave been prepared and identified with the FT-IR, XRD, BET, and XRF methods. The results showed the Clinoptilolite and Ferrocarpholite structure with an average particle size of 30, 38.7 nanometer, and a specific surface area of 28.51 and 4.78 m2/g for Firoozkooh and Tabriz zeolites, respectively. The effects of different variables such as pH, time of contact between the exchanger and solution, initial concentration of ions and the amount of adsorbent were investigated and optimum conditions for separation of these ions were determined. The maximum adsorption of thorium ions on both adsorbents under optimum experimental conditions was observed at 25 mg/L, pH=4, 240 min. and weight of 0.1 g, 96.93% and 96.77%, and for uranium ion, the maximum adsorption was at 25 mg/L, pH=4 for Firouzkohe zeolite and  pH=5 for Tabriz zeolite, 240 min. contact time, 0.1 g weight, 93.01% and 52.68% respectively by zeolites of Firouzkooh and Tabriz, which increased the mass of zeolite in Tabriz up to 0.3 g, the highest uranium uptake reached 83.65%.