Adsorption Of UO₂²⁺ And Th⁴⁺ On Modified Hydroxyapatite By Acrylonitrile/amidoxime

In this article, Hydroxyapatite（HAP） grafted acrylonitrile and amidoxime group was synthesized and characterized by FT-IR, XRD, SEM and TGA. Adsorption of UO₂²⁺and Th⁴⁺from aqueous solution were studied in a series of batch experiments.In the batch experiments, effect of pH value, adsorbent dose, contact time, ionic strength,initial concentration of UO₂²⁺and Th⁴⁺ and temperature were investigated. Then desorption and selectivity experiments were also studied.The results show that: the adsorption efficiency of the modified hydroxyapatite is obviously better than the traditional hydroxyapatite. The adsorption efficiency of these adsorbent for both UO₂²⁺and Th⁴⁺ were influenced greatly by pH value, adsorbent dose, contact time and temperature. All the adsorption process is fast which can reach the equilibrium within 30 minutes,and the ionic strength shows negligible effect on the UO₂²⁺, while great influence on the Th⁴⁺. The adsorption kinetics indicates that, the adsorption process of both UO₂²⁺and Th⁴⁺ obey the pseudo-second-order chemisorption. Langmuir model fit the adsorption experiment well, the adsorption experiment is endothermic（ΔH>0） and spontaneous（ΔG<0）.With the lower costs, higher adsorption speed and better adsorption ability, the composite was a potential adsorbent to separate UO₂²⁺ from the solution.