Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States.
Environ Sci Technol. 2015 May 5;49(9):5476-83. doi: 10.1021/es506363x. Epub 2015 Apr 20.
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.
由于氧化铈（CeO2）纳米粒子（NPs）的毒性，需要更好地了解氧化铈 NPs 的氧化还原反应引起的表面性质变化及其在自然和工程水系统中的传输。本研究调查了与二价铁离子（Fe2+）的氧化还原反应对 CeO2 NPs 胶体稳定性的影响。我们证明，在厌氧条件下，在 pH 值为 4.8 的 3 mM FeCl2 溶液中悬浮的 CeO2 NPs 比在没有 Fe2+的情况下更稳定，不易沉降。CeO2 NPs 和 Fe2+之间的氧化还原反应导致在 CeO2 表面上形成 6 线水铁矿，这通过增加 CeO2 NPs 的动电电势和亲水性来提高胶体稳定性。这些氧化还原反应可以通过增加铈的溶解和形成新的 Fe（III）（水合）氧化物反应性表面层来影响 CeO2 NPs 的毒性。因此，这些发现对于阐明环境中氧化还原反应性 NPs 的相变和传输具有重要意义。
