Interfacial reaction of SnII on mackinawite (FeS)

Dulnee, Siriwan; Scheinost, Andreas C.

doi:10.1016/j.jconhyd.2015.03.012

Cited by 7 publications

(6 citation statements)

References 64 publications

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“…The uptake of Ni by mackinawite was characterized by multiple processes which proceeded towards equilibrium on different time scales. These findings are consistent with previous studies of bivalent metal uptake by mackinawite (Framson and Leckie, 1978, Parkmann et al, 1999, Coles et al, 2000, Jeong et al, 2007, Liu et al, 2008, Zavašnik et al, 2014, Dulnee and Scheinost, 2015 and reinforce the significant interest FeS has received in environmental studies.…”

Section: Discussionsupporting

confidence: 92%

“…3.3.1. Surface sorption-Previous experimental studies used periods of 24-48 h for evaluating metal retention by mackinawite (Parkmann et al, 1999, Coles et al, 2000, Jeong et al, 2007, Liu et al, 2008, Dulnee and Scheinost, 2015; a 24 h reaction time appears to be more prevalently adopted in these studies. Time trends of Ni concentration in solution for systems with 1.1 g FeS/L and molar ratios of [Ni(II)]/[FeS] equal to 0.19 and 0.52 showed an initial period (< 1 h) of rapid Ni removal from solution followed by a period from about 1 to 55 h with slower Ni uptake ( Fig.…”

Section: Batch Studiesmentioning

confidence: 99%

“…Disordered-FeS, mackinawite, and greigite (Fe 3 S 4 ) together comprise the dominant components of solid-phase acid volatile sulfide (AVS) in sediments and aquifersolids and are possible precursors to the formation of pyrite (e.g., Berner, 1964, Schoonen and Barnes, 1991a, Rickard and Morse, 2005, Hunger and Benning, 2007. All of these iron sulfides, especially mackinawite, have capacity to remove bivalent metals from solution, such as lead, cadmium, nickel, manganese, copper, tin, and mercury (Jean and Bancroft, 1986, Parkmann et al, 1999, Coles et al, 2000, Jeong et al, 2007, Liu et al, 2008, Zavašnik et al, 2014, Dulnee and Scheinost, 2015. Consequently, iron sulfides are important sinks for trace metals in anoxic environments and may be advantageous for use in environmental applications to treat metalcontaminated water (Saunders et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Uptake of nickel by synthetic mackinawite

Wilkin

Beak

2017

Chemical Geology

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The uptake of aqueous Ni(II) by synthetic mackinawite (FeS) was examined in anaerobic batch experiments at near-neutral pH (5.2 to 8.4). Initial molar ratios of Ni(II) to FeS ranged from 0.008 to 0.83 and maximum Ni concentrations in mackinawite, expressed as the cation mol fraction, were as high as = 0.56 (Fe Ni S; 0 ≤ ≤ 1). Greater than 99% Ni removal from solution occurred when Ni loading remained below 0.13 ± 0.03 (1) mol Ni per mol FeS due to sorption of Ni at the mackinawite surface. Characterization of experimental solids using X-ray diffraction and Raman spectroscopy showed patterns characteristic of nanocrystalline mackinawite; no evidence of nickel monosulfide (α-NiS or millerite), polydymite (NiS), or godlevskite [(Ni,Fe)S] formation was indicated regardless of the amount of Ni loading. Slight expansion of the -axis correlated with increasing Ni content in synthetic mackinawite, from = 5.07 ± 0.01 Å at = 0.02 to = 5.10 ± 0.01 Å at = 0.38. Ni-edge extended X-ray absorption fine structure (EXAFS) spectra of synthetic Ni-bearing mackinawite are similar in phase and amplitude to the Fe -edge EXAFS spectrum of Ni-free mackinawite, indicating that the molecular environment of Ni in Ni-bearing mackinawite is similar to that of Fe in Ni-free mackinawite. EXAFS data fitting of Ni-bearing mackinawite with = 0.42 indicated a coordination number of 4.04 ± 0.30 and an average Ni_S bond distance of 2.28 Å, in good agreement with the Fe_S bond distance of 2.26 Å in mackinawite, tetrahedral Fe coordination, and slight lattice expansion along the-axis. At lower Ni loadings ( = 0.05-0.11), EXAFS analysis showed a decrease in Ni_S coordination towards CN = 3, which reflects the influence of sorbed Ni. Continued Ni uptake, past the maximum amount of sorption, was accompanied by proportional molar release of Fe to solution. Interstitial occupancy of Ni within the mackinawite interlayer may be transitional to structural substitution of Fe. The Ni-mackinawite solid-solution is described by a one-site binary mixing model: where is the distribution coefficient, is the ratio of equilibrium constants for Ni-mackinawite and mackinawite (14.4 ± 1.3), is an ion interaction parameter, and is the mole fraction of end-member NiS in the solid solution. The experimentally determined value of is 17.74 ± 1.15 kJ/mol and indicates significant non-ideality of the solid solution. Transformation processes were evaluated by aging Ni-mackinawite with polysulfides and solutions saturated with air. Reaction of Ni-mackinawite with polysulfides led to the formation of pyrite (FeS) and Ni retention in the solid phase. When Ni-mackinawite was aged in the presence of dissolved oxygen, transformation to goethite (FeOOH) and violarite (FeNiS) was observed.

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Section: Discussionsupporting

confidence: 92%

Section: Batch Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Uptake of nickel by synthetic mackinawite

Wilkin

Beak

2017

Chemical Geology

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“…Magnetite and mackinawite were synthesized following the well-established methods reported in ref. [29][30][31][32] (experimental description summarized in Table S1 in the ESI †). Both solid phases were equilibrated for 4 weeks in the original synthesis solution, washed three times with the corresponding background electrolyte (0.1 M NaCl) and equilibrated in this solution for 3 weeks.…”

Section: Fe Mineralsmentioning

confidence: 99%

Systematic XAS study on the reduction and uptake of Tc by magnetite and mackinawite

Yalçıntaş

Scheinost²,

Gaona

et al. 2016

Dalton Trans.

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The mechanisms for the reduction and uptake of Tc by magnetite (FeO) and mackinawite (FeS) are investigated using X-ray absorption spectroscopy (XANES and EXAFS), in combination with thermodynamic calculations of the Tc/Fe systems and accurate characterization of the solution properties (pH, pe, [Tc]). Batch sorption experiments were performed under strictly anoxic conditions using freshly prepared magnetite and mackinawite in 0.1 M NaCl solutions with varying initial Tc(vii) concentrations (2 × 10 and 2 × 10 M) and Tc loadings (400-900 ppm). XANES confirms the complete reduction of Tc(vii) to Tc(iv) in all investigated systems, as predicted from experimental (pH + pe) measurements and thermodynamic calculations. Two Tc endmember species are identified by EXAFS in the magnetite system, Tc substituting for Fe in the magnetite structure and Tc-Tc dimers sorbed to the magnetite {111} faces through a triple bond. The sorption endmember is favoured at higher [Tc], whereas incorporation prevails at low [Tc] and less alkaline pH conditions. The key role of pH in the uptake mechanism is interpreted in terms of magnetite solubility, with higher [Fe] and greater recrystallization rates occurring at lower pH values. A TcS-like phase is predominant in all investigated mackinawite systems, although the contribution of up to 20% of TcO·xHO(s) (likely as surface precipitate) is observed for the highest investigated loadings (900 ppm). These results provide key inputs for an accurate mechanistic interpretation of the Tc uptake by magnetite and mackinawite, so far controversially discussed in the literature, and represent a highly relevant contribution to the investigation of Tc retention processes in the context of nuclear waste disposal.

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“…This means that during the ED process the sample should be theoretically placed at the anode compartment, where an acidic pH (below 2) is promoted and, as a consequence, higher desorption rates are expected. Considering the ED system, it is foreseen that the most common forms of As, Cu, Sn and W, in extreme acidic conditions and with soluble forms at pH below 2 are, respectively, H3AsO4/H3AsO3 (Chen et al, 2014), Cu 2+ /Cu(OH) + (Cuppett et al, 2006), Sn 2+ /Sn(OH) 3+ (Dulnee and Scheinost, 2015) and WO3 (Cao and Guo, 2019). Nevertheless, the mobility of these elements during ED experiments may be limited due to eventual complexation with other substances present in the media (Almeida et al, 2020b).…”

Section: Tinmentioning

confidence: 99%