Preparation of amino-functionalized starch-based adsorbent and its adsorption behavior for uranyl ions

Starch not only has the advantage of inexpensive and biodegradable compared to other adsorbed materials but also contains a large amount of chemically modified hydroxyl groups. Using starch as the raw material, an amino-functionalized starch-based adsorbent was prepared by a three-step reaction of esterification-crosslinking- aminolysis. The samples were characterized by FTIR, EDS, and XPS. The adsorption performance of amino-functionalized starch-based adsorbents for uranyl ions in aqueous solutions was studied, and the adsorption kinetics and adsorption thermodynamics were analyzed. The results show that after the starch-based adsorbent is functionalized with amino groups. Its adsorption performance for uranyl ions is significantly improved. The adsorption behavior of amino-functionalized starch-based adsorbents for uranyl ions conforms to the Langmuir isotherm adsorption model and the quasi-second-order adsorption kinetic equation. The adsorption process mainly depends on the coordination and chelation between uranyl ions and -NH₂ on the surface of the adsorbents. And the adsorption process is exothermic. Finally, satisfactory results were obtained under gentle conditions. Under the conditions of pH 6, C₀ of 35 mg/g, T of 25 ℃, m of 0.25 g/L, and t of 5 h, the adsorption capacity of the adsorbent for uranyl ions is 118.92 mg/g. This shows that the amino-functionalized starch-based adsorbent has potential application prospects in terms of nuclear energy-containing uranium wastewater. (author)