Spectroscopic investigation of magnetite surface for the reduction of hexavalent chromium

Jung, Yoojin; Choi, Jeong‐Yun; Lee, Woojin

doi:10.1016/j.chemosphere.2007.02.028

Cited by 91 publications

(54 citation statements)

References 27 publications

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“…These results are consistent with the formation of a passivating layer during metal reduction. [32][33][34] Nanoparticulate UO 2 growth rates observed by AFM are consistent with U(VI) reduction rates determined by the GI-XANES analysis; the U L III -edge position moves to lower energy values within 2-4 hours after exposure of U(VI) to the magnetite (111) surface (Fig. 2) but reached a plateau around 8 hours, roughly the same time that the AFM data indicated slowing precipitate formation.…”

Section: Nanoparticulate Uo 2 Growth and U(vi) Reduction Ratessupporting

confidence: 68%

U(VI) Sorption and Reduction Kinetics on the Magnetite (111) Surface

Singer

Chatman

Ilton

et al. 2012

Environ. Sci. Technol.

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continuous batch-flow conditions. We observed, in real-time and in situ, adsorption and reduction of U(VI) and subsequent growth of UO 2 nanoprecipitates using atomic force microscopy (AFM) and newly developed batch-flow U L III -edge grazing-incidence x-ray absorption spectroscopy near-edge structure (GI-XANES) spectroscopy. U(VI) reduction occurred with and without CO 3 present, and coincided with nucleation and growth of UO 2 particles. When Ca and CO 3 were both present no U(VI) reduction occurred and the U surface loading was lower. In situ batch-flow AFM data indicated that UO 2 particles achieved a maximum height of 4-5 nm after about 8 hours of exposure, however, aggregates continued to grow laterally after 8 hours reaching up to about 300 nm in diameter. The combination of techniques indicated that U uptake is divided into three-stages; (1) initial adsorption of U(VI),(2) reduction of U(VI) to UO 2 nanoprecipitates at surface-specific sites after 2-3 hours of exposure, and (3) completion of U(VI) reduction after ~6-8 hours. U(VI) reduction also corresponded to detectable increases in Fe released to solution and surface topography changes.Redox reactions are proposed that explicitly couple the reduction of U(VI) to enhanced release of Fe(II) from magnetite. Although counter intuitive, the proposed reaction stoichiometry was shown to be largely consistent with the experimental results. In addition to providing molecularscale details about U sorption on magnetite, this work also presents novel advances for collecting surface sensitive molecular-scale information in real-time under batch-flow conditions. 3

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Section: Nanoparticulate Uo 2 Growth and U(vi) Reduction Ratessupporting

confidence: 68%

U(VI) Sorption and Reduction Kinetics on the Magnetite (111) Surface

Singer

Chatman

Ilton

et al. 2012

Environ. Sci. Technol.

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“…6(C) shows O 1 s spectra, from which the peak of O1S was located at 531.4 ± 0.1 eV. This binding energies represented metal-hydroxide (M-OH) bonds [20]. Therefore, the data from XPS patterns indicated that chromium species of the chromate reduction product was in the form of Cr (III) hydroxides.…”

Section: Cr (Vi)-reducing Capacity Of Bacterial Isolatesmentioning

confidence: 97%

Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag

Chai

Huang

Yang

et al. 2009

Journal of Hazardous Materials

130

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“…Removal of heavy metals by nanoparticles would provide significant reductions in cost, time, and labor to industry and result in improved environmental stewardship [4]. Magnetite is widespread in the environment and recently, some researches have focused on utilization of nanoscale magnetite to remove heavy metals mainly including Cr(VI) [3,[5][6][7], Hg(II) [8], As(V) [9], Sb(V) [10], Se(IV) [11], and V(V) [5]. However, very few experimental studies were reported in the literature on the other common heavy metal ions (e.g., Ni(II), Pb(II), Cu(II)) interactions with nanoscale magnetite.…”

Section: Introductionmentioning

confidence: 99%

Removal of Ni(II) from Aqueous Solutions by Nanoscale Magnetite

Wang

Ren

et al. 2010

CLEAN Soil Air Water

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Magnetite nanoparticles were applied to remove Ni(II) from aqueous solutions as a function of pH, contact time, supporting electrolyte concentration, and analytical initial Ni(II) concentration. The highly crystalline nature of the magnetite structure with diameter of around 10 nm was characterized with transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The surface area was determined to be 115.3 m 2 /g. Surface chemical properties of magnetite at 258C in aqueous suspensions were investigated. The point of zero charge (pHzpc) was found to be 7.33 and the intrinsic acidity constants (pK s a1 and pK s a2 ) were found to be 9.3 and 5.9, respectively. The surface functional groups were investigated with Fourier transform-infrared spectroscopy (FTIR) as well. Batch experiments were carried out to determine the adsorption kinetics and mechanism of Ni(II) by these magnetite nanoparticles. The adsorption process was found to be pH dependent. In NaCl solutions, Ni(II) adsorption increased with increasing ionic strength while in NaClO 4 solutions, Ni(II) adsorption exhibited little dependence on the ionic strength of the solution. The adsorption process better followed the pseudo-second order equation and Freundlich isotherm.

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Spectroscopic investigation of magnetite surface for the reduction of hexavalent chromium

Cited by 91 publications

References 27 publications

U(VI) Sorption and Reduction Kinetics on the Magnetite (111) Surface

U(VI) Sorption and Reduction Kinetics on the Magnetite (111) Surface

Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag

Removal of Ni(II) from Aqueous Solutions by Nanoscale Magnetite

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