Cerium oxide (CeO2) nanoparticles are an emerging wastewater contaminant which are highly redox active. However, there is only limited information regarding their fate and transport in aqueous environments where redox-active species may coexist. Therefore, we investigated changes in Ce(IV)O2 nanoparticle surface properties and secondary phase formation in the presence of Fe2+ and Cr(VI)(aq) species which can coexist in water treatment processes. In Fe2+-Cr(VI)(aq) systems, enhanced CeO2 colloidal stability and inhibited CeO2 dissolution was observed compared to systems without Cr(VI)(aq). This results from the formation of Fe(III) phases on the CeO2 surface based on X-ray photoelectron and X-ray absorption spectroscopy results. Interestingly, heterogeneous and homogeneous Fe(III) (hydr)oxide formation increased with increasing Cr(VI)(aq) concentration. This indicates faster Fe2+ oxidation kinetics by Cr(VI)(aq) over Ce4+, which did not follow the thermodynamic prediction. Cr(VI)-promoted Fe(III)(s) formation on CeO2 nanoparticle surfaces creates mobile and hybrid CeO2-Fe(III) natural-engineered nanocomposite sorbents for aqueous contaminants.

Effect of Fe2+ and Cr(VI) on redox-active CeO2 nanoparticle surface properties and transformation in aqueous systems

251st National Meeting (2016)

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