As a natural and low-cost material, glauconite is applied as an adsorbent to remove Th 4+ and UO 2 2+ ions from aqueous solutions by a batch system. Two different samples of glauconite (dark green and light green color) are delivered from Baharia Oases, Egypt. The effects of analytical parameters such as pH, contact time, concentration of metal ion, mass adsorbent, interfering ions, and temperature on adsorption on glauconite (dark green) are investigated. The similar uptake percentage of the

more »

... o different glauconite samples (dark green and light green) at certain condition verify the role of Si-OH in the proposed adsorption mechanism. Isotherm studies of the adsorption are also carried out to understand the nature of adsorption of Th 4+ and UO 2 2+ ions on glauconite (dark green). Equilibrium data are best fitted with Langmuir model. The adsorption capacity of Th 4+ and UO 2 2+ ions is found to be 50 and 40 mgg -1 , respectively. Thermodynamic parameters ΔH o , ΔS o and ΔG o values showed that the sorption process was endothermic (ΔH o > 0), had increased entropy (ΔS o > 0) and spontaneous (ΔG o < 0). The retained metals are eluted by using different reagents. The preconcentration could be made selective to UO 2 2+ ions by using HNO 3 0.1 M, NaCl 0.9 M and oxalic acid 0.1 M rather than Th 4+ ions.