title: Enhanced Colloidal Stability of CeO2 Nanoparticles by Ferrous Ions: Adsorption, Redox Reaction, and Surface Precipitation.
abstract: Due to the toxicity of cerium oxide (CeO2) nanoparticles (NPs), a better understanding of the redox reaction-induced surface property changes of CeO2 NPs and their transport in natural and engineered aqueous systems is needed. This study investigates the impact of redox reactions with ferrous ions (Fe2+) on the colloidal stability of CeO2 NPs. We demonstrated that under anaerobic conditions, suspended CeO2 NPs in a 3 mM FeCl2 solution at pH 4.8 were much more stable against sedimentation than those in the absence of Fe2+. Redox reactions between CeO2 NPs and Fe2+ lead to the formation of 6-line ferrihydrite on the CeO2 surfaces, which enhanced the colloidal stability by increasing the zeta potential and hydrophilicity of CeO2 NPs. These redox reactions can affect the toxicity of CeO2 NPs by increasing cerium dissolution, and by creating new Fe(III) (hydr)oxide reactive surface layers. Thus, these findings have significant implications for elucidating the phase transformation and transport of redox reactive NPs in the environment.
authors: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States.
authors: Xuyang
authors: X
authors: Liu
authors: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States.
authors: Jessica R
authors: JR
authors: Ray
authors: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States.
authors: Chelsea W
authors: CW
authors: Neil
authors: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States.
authors: Qingyun
authors: Q
authors: Li
authors: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States.
authors: Young-Shin
authors: YS
authors: Jun
mesh_terms: D000327:Adsorption; D002563:Cerium / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007501:Iron / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D013499:Surface Properties
chemical_list: D003102:Colloids; D005290:Ferric Compounds; D007477:Ions; D002563:Cerium; C030583:ceric oxide; C092844:ferric oxyhydroxide; D007501:Iron