Adsorption of U(VI) onto Amidoxime-functionalized Hydrothermal Carbon in the Presence of Ca-U(VI)-CO3 Complexes

Abstract

The aim is collecting uranium from groundwater in which uranium mainly exists in negative species, the amidoxime-functionalized hydrothermal carbon (AO-HTC) was synthesized. From the results of N2 adsorption-desorption and SEM, AO-HTC is a small spherical surface; FT-IR and Elemental analysis showed that the amidoxime group was successfully grafted onto the surface of the material; Zeta-potential measurement showed that the amino nitrogen atom is protonated in the oxime group. The optimum pH value of AO-HTC for uranium adsorption is 6.0, and the adsorption equilibrium is reached within 80 min, which is in accordance with the pseudo-second order adsorption kinetic model. The adsorption of uranium by AO-HTC accords with the Langmuir isotherm adsorption model, and the single-layer saturated adsorption capacity is 254.13mg·g-1. The thermodynamic parameters calculated by the adsorption isotherm indicate that AO-HTC adsorption of uranium is a spontaneous endothermic chemical process and Carbonate ion, calcium ion and humic acid concentration have great influence on uranium adsorption. The experiments results show that AO-HTC has the potential to elimination of U(VI) from groundwater.