High performance polydopamine-functionalized mesoporous silica nanospheres for U(VI) removal

This work reports the fabrication of polydopamine-functionalized mesoporous silica (mSiO(2)/PDA) nanospheres for removing U(VI) from aqueous solution. The maximum adsorption capacity of mSiO(2)/PDA is 332.3mg/g at 318.15 K and pH = 5.5. In comparison to the pristine mSiO(2), the adsorption capacity of mSiO(2)/PDA has been remarkably enhanced, which can be ascribed to the large amounts of functional groups existed on the surface of mSiO(2)/PDA. The adsorption process fits well with the pseudo-second-order kinetics model. The adsorption isotherm follows the Langmuir isotherm model, revealing a monolayer adsorption of U(VI) onto mSiO(2)/PDA. Thermodynamic analysis indicates a spontaneous and endothermic adsorption process. Additionally, this adsorption process is pH-dependent, while the effect of ionic strength is negligible. (C) 2017 Elsevier B.V. All rights reserved.