Impacts of Aqueous Mn(II) on the Sorption of Zn(II) by Hexagonal Birnessite

Lefkowitz, Joshua P.; Elzinga, Evert J.

doi:10.1021/es506019j

Cited by 61 publications

(51 citation statements)

References 53 publications

(105 reference statements)

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“…Such an evolution was consistent with previous studies (Elzinga, 2011(Elzinga, , 2016Lefkowitz et al, 2013;Lefkowitz & Elzinga, 2015). In the following section, the mechanisms of transformation were studied at the crystal scale, hypothesizing that an increased concentration of Mn 2þ led to an increased conversion of d-MnO 2 to synthetic feitknechtite without significant dissolution of d-MnO 2 .…”

Section: Mineralogical Evolutionsupporting

confidence: 88%

“…The present description of the vernadite-to-feitknechtite transformation, from macroscopic to crystal scales, is consistent with our current understanding of this transformation (Elzinga, 2011(Elzinga, , 2016Lefkowitz et al, 2013;Lefkowitz & Elzinga, 2015). One of the key findings is the major role of oriented aggregation in the nucleation and growth of feitknechtite from d-MnO 2 precursors.…”

Section: The Role Of Oriented Aggregation In Nanoparticle Growthsupporting

confidence: 87%

“…Feitknechtite, whose structure is built of layers of (Mn 3þ O 6 ) 9À octahedra, may upon ageing convert to manganite (g-MnOOH) at pH 7.0-7.5 or to hausmannite (Mn 3 O 4 ) at pH > 8 (Elzinga, 2011;Lefkowitz et al, 2013;Lefkowitz & Elzinga, 2015).…”

Section: Mn 2þmentioning

confidence: 99%

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Nucleation and growth of feitknechtite from nanocrystalline vernadite precursor

Grangeon¹,

Warmont²,

Tournassat³

et al. 2017

ejm

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Vernadite is a nanocrystalline manganese oxide, which controls the fate of many trace elements in soils and sediments through sorption and oxidative-degradation mechanisms. This exceptional reactivity directly results from its crystal structure, which may however evolve upon contact with redox-sensitive species. Understanding these changes is a prerequisite to predict and model the geochemical cycle of trace elements in the environment. Here, the structural and morphological modifications affecting synthetic nanocrystalline vernadite (d-MnO 2 ) upon contact with increasing concentrations of Mn 2þ were investigated using wet chemistry, synchrotron X-ray diffraction and transmission electron microscopy. Fresh d-MnO 2 crystals had an Mn oxidation state of 3.94 ± 0.05 and a ∼10 A layer-to-layer distance. Crystal size was ∼10 nm in the layer plane, and ∼1 nm perpendicular to that. Upon contact with aqueous Mn 2þ under anoxic conditions, d-MnO 2 crystals underwent several morphological and mineral evolutions, starting with the stacking, perpendicular to the layer plane, of d-MnO 2 crystals to form crystals ∼10 nm Â 2 nm which were then subjected to oriented aggregation both along and perpendicular to the layer plane to form lath-like crystals with dimensions of ∼100 nm Â 20 nm. Finally, these laths stacked perpendicular to the layer plane to form synthetic feitknechtite (b-MnOOH) crystals with sizes up to ∼100 nm Â 500 nm when the Mn 2þ loading reached 31.9 mmol g À1 . Structural transformation from d-MnO 2 to synthetic feitknechtite was detected at Mn 2þ loading equal to or higher than 3.27 mmol g À1 . These mechanisms are likely to influence the geochemical fate of trace elements in natural settings where Mn 2þ is abundant. Firstly, the systematic increase in crystal size with increasing Mn 2þ loading may impact the sorption capacity of vernadite and feitknechtite by reducing the density of reactive edge sites. Secondly, the fate of trace elements initially sorbed at the vernadite surface is unclear, as they could either be released in solution or incorporated into the feitknechtite lattice.

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Section: Mineralogical Evolutionsupporting

confidence: 88%

Section: The Role Of Oriented Aggregation In Nanoparticle Growthsupporting

confidence: 87%

See 1 more Smart Citation

Nucleation and growth of feitknechtite from nanocrystalline vernadite precursor

Grangeon¹,

Warmont²,

Tournassat³

et al. 2017

ejm

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“…27,28 Therefore, manganese oxide plays an extremely important role in controlling the migration and conversion of pollutants in the environment. 29…”

Section: Introductionmentioning

confidence: 99%

Efficient Adsorption of the Cd(II) and As(V) Using Novel Adsorbent Ferrihydrite/Manganese Dioxide Composites

Meng

Zhang

et al. 2019

ACS Omega

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Ferrihydrite/manganese dioxide composites (FH–M) were synthesized from ferrihydrite (FH) and manganese compounds by ex situ synthesis and characterized using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy in the present work. The influences of experimental parameters such as the solution pH value and initial concentration of adsorbate on the adsorption uptake of Cd(II)/As(V) was systematically investigated. The adsorption kinetics was analyzed by fitting quasi-first-order and quasi-second-order kinetic equations. The results showed that with increase in the pH value, the adsorption rate of Cd(II) is increased, while that of As(V) is increased first and then decreased. For the kinetic adsorption process, the adsorption performance of FH–M to As(V) was better than that to Cd(II). The quasi-second-order kinetic equation and Freundlich equation were more suitable to describe the adsorption of Cd(II)/As(V). The ligand exchange of Cd(II)/As(V) with the −OH in the composites was confirmed by analyzing the characterization results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The high adsorption ability of the FH–M makes it a potentially attractive adsorbent for the removal to Cd(II) and As(V) with a good application prospect.

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“…15,16 Due to their high specic surface areas and structures with highly reactive vacancy sites, these phyllomanganates can absorb metals, such as Zn(II), Cu(II), Pb(II) and Ni(II). [17][18][19] However, these materials can also readily oxidize many reduced toxic metals and metalloids, such as As(III), Cr(III), and Co(II), [20][21][22][23] as well as organic contaminants. 24,25 Many Mn oxides found in surface environments are poorly crystalline, of biogenic origin and highly reactive.…”

Section: Introductionmentioning

confidence: 99%