U(VI) reduction by Fe(II) on hematite nanoparticles

Springer Science and Business Media LLC - Tập 13 - Trang 3741-3754 - 2011
Hui Zeng1,2, Daniel E. Giammar1,3
1Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, USA
2TLC EnviroTech, Dallas, USA
3Center for Materials Innovation, Washington University, St. Louis, USA

Tóm tắt

Nanoscale size effects on U(VI) reduction by Fe(II) on hematite were investigated with four aerosol-synthesized hematite nanoparticles (12, 30, 50, 125 nm) and one aqueous-synthesized hematite (70 nm). Batch experiments were conducted at loadings of 0.01 mM U(VI) and 5 mM Fe(II) at pH 7.5 and 9.0. Rate constants for reduction of U(VI) to U(IV) were determined using a pseudo-first order reaction rate law. Reduction was faster at pH 7.5 than at pH 9.0. Rate constants were higher for aerosol-synthesized hematite than for aqueous-synthesized hematite. Rate constants were not significantly different for the 30, 50, and 125 nm particles. However, reduction was two orders of magnitude faster for the 12 nm hematite particles. Possible explanations for the dramatically faster reduction with the 12 nm hematite include the formation of a more reactive solid such as magnetite, effects on electron conduction through hematite, and quantum confinement effects.

Tài liệu tham khảo

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