Uranium(VI) Adsorption Using a Mixture of 1-Amino-2-naphthol-4-sulfonic Acid and Bentonite: Kinetic and Equilibrium Studies

Uranium was adsorbed using bentonite treated with 1-amino-2-naphthol-4-sulfonic acid (ANSA). The prepared Bt-(ANSA) was characterized, and its adsorption affinity for uranium(VI) was evaluated. The influence exerted on the uranium adsorption by pH, contact time, adsorbent dose, initial uranium concentration, interfering ions, and temperature was studied. The optimum conditions are pH 8.5, 0.04 g of Bt-(ANSA) per 10 mL of 400 mg/L uranium solution, and 20-min contact at room temperature. The majority of cations except Th, Fe, Cu, and Ni do not interfere with the uranium adsorption. The adsorption kinetics and equilibrium were studied. The application of the Langmuir model showed that the maximum sorption capacity reached 90.9 mg/g at room temperature. The adsorption process was found to follow a pseudo-second order kinetic model at 400 mg/L uranium concentration. Evaluation of thermodynamic parameters (Delta G degrees, Delta H degrees, and Delta S degrees) shows that the adsorption is spontaneous exothermic accompanied by a decrease in randomness. Uranium(VI) ions were efficiently desorbed using a 1 M HNO(3)solution with the adsorbent regeneration. The optimum conditions were applied to separate uranium from carbonate leach liquor solution of a field sample from Abu Hamatta area, SW Sinai, Egypt.