Characteristics of equilibrium and kinetic for U(VI) adsorption using novel diamine-functionalized hollow silica microspheres

The diamine-functionalized hollow silica microspheres (DA-HSM) were successfully synthesized for highly efficient sorption of U(VI). The sorption of U(VI) on DA-HSM may be proceeded through anion-exchange and adduct-type mechanism at low pH and amine-U(VI) chelation at high pH. The sorption kinetic could be described by the pseudo-second-order model; whereas the sorption isotherms could be fitted by the Langmuir model with the maximum mono-layer sorption capacity of 126.6 mg/g at 298 K. U(VI) sorption on DA-HSM was endothermic, spontaneous, and feasible in nature. The DA-HSM could be regenerated and reused without significant reduction of the sorption capacities. (author)