Evidence for the nucleation and epitaxial growth of Zn phyllosilicate on montmorillonite

Schlegel, Michel L.; Manceau, Alain

doi:10.1016/j.gca.2005.10.021

Cited by 73 publications

(82 citation statements)

References 59 publications

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“…1). In Zn-rich phyllosilicates, backscattering of tetrahedral Si cations causes the upward oscillation at 5 Å À1 to be prominent (Schlegel et al, 2001a;Schlegel and Manceau, 2006). In contrast, a shoulder instead of a well resolved peak is observed around 5 Å À1 in the spectrum of Zn-LDH (Fig.…”

Section: Pca-tt Analysis Of Soil Exafs Spectramentioning

confidence: 94%

Soil properties controlling Zn speciation and fractionation in contaminated soils

Jacquat

Voegelin

Kretzschmar

2009

Geochimica et Cosmochimica Acta

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Section: Pca-tt Analysis Of Soil Exafs Spectramentioning

confidence: 94%

Soil properties controlling Zn speciation and fractionation in contaminated soils

Jacquat

Voegelin

Kretzschmar

2009

Geochimica et Cosmochimica Acta

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“…The difference between the spectra of the two compounds results from the occurrence of tetrahedral sheets in phyllosilicates, for which Zn-rich kerolite (trioctahedral) and Zn-substituted Redhill montmorillonite (dioctahedral) are used as a proxy. The spectrum of ZnKer240 has an oscillation near $5.2 Å À1 caused by the presence of tetrahedral Si, whereas the spectrum of Zn-LDH has only a shoulder at this k-value (Schlegel et al, 2001b;Panfili et al, 2005;Schlegel and Manceau, 2006). In the reconstructed spectrum of Zn-LDH (Fig.…”

Section: Identification Of Zn Speciesmentioning

confidence: 97%

“…The database contained smithsonite (from a natural sample), willemite, hemimorphite, franklinite, gahnite , sphalerite (Schuwirth et al, 2007), zincite (Voegelin et al, 2005), hydrozincite (Jacquat et al, 2008), a series of Zn-containing kerolites (Si 4 (Zn x Mg 3Àx )O 10 (OH) 2 ÁnH 2 O) with x = 0.03, 1.35 or 3.00 (Manceau et al, 2000;Schlegel et al, 2001a) or x = 2.40 (Voegelin et al, 2005), trioctahedral Zn-phyllosilicate precipitated at the layer edges of montmorillonite, Zn-sorbed montmorillonite (Schlegel and Manceau, 2006), natural Zn-substituted Redhill montmorillonite , Zn layered double hydroxide (Zn-LDH, Zn 2 Al(OH) 6 Cl; Voegelin et al, 2005), Zn-substituted goethite (Manceau et al, 2000), Zn-sorbed ferrihydrite, Zn-reacted gibbsite , Zn-reacted hydroxylapatite at pH 5 and pH 6 and at various metal concentrations (Panfili et al, 2005), Zn parahopeite, Zn acetate, Zn citrate, Zn malate, Zn oxalate, Zn phytate, Zn sorbed on humic and fulvic acids at various concentrations, and aqueous Zn (ZnNO 3 solution at pH 4) (Sarret et al, , 2004.…”

Section: Powder Zn K-edge Exafs Spectroscopymentioning

confidence: 99%

Zinc speciation in mining and smelter contaminated overbank sediments by EXAFS spectroscopy

Damme

Degryse

Smolders

et al. 2010

Geochimica et Cosmochimica Acta

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International audienceOverbank sediments contaminated with metalliferous minerals are a source of toxic metals that pose risks to living organisms. The overbank sediments from the Geul river in Belgium contain 4000–69,000 mg/kg Zn as a result of mining and smelting activities, principally during the 19th century. Three main Zn species were identified by powder Zn K-edge EXAFS spectroscopy: smithsonite (ZnCO3), tetrahedrally coordinated sorbed Zn (sorbed IVZn) and Zn-containing trioctahedral phyllosilicate. Smithsonite is a primary mineral, which accounts for approximately 20–60% of the Zn in sediments affected by mining and smelting of oxidized Zn ores (mostly carbonates and silicates). This species is almost absent in sediments affected by mining and smelting of both sulphidic (ZnS, PbS) and oxidized ores, presumably because of acidic dissolution associated with the oxidation of sulphides, as suggested by the lower pH of this second type of sediment (pH(CaCl2) <7.0 vs. pH(CaCl2) >7.0 for the first type). Thus, sulphide minerals in sediment deposits can act as a secondary source of dissolved metals by a chemical process analogous to acid mine drainage. The sorbed IVZn component ranges up to approximately 30%, with the highest proportion occurring at pH(CaCl2) <7.0 as a result of the readsorption of dissolved Zn2+ on sediments constituents. Kerolite-like Zn-rich phyllosilicate is the major secondary species in all samples, and in some the only detected species, thus providing the first evidence for pervasive sequestration of Zn into this newly formed precipitate at the field scale

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“…Regarding the third possibility -initial Zn-phyllosilicate formation followed by Zn-LDH precipitation at increasing Zn loading -it is worth noting that this interpretation is in line with the trend in precipitate type observed in our bulk soils. Concerning the fourth possibility, examples for layered Zn-species with structural features of both Zn-kerolite and (Cesàro, 1927) (Schlegel et al, 2001;Schlegel and Manceau, 2006). The signal from nextnearest Si is also prominent in ZnMg-kerolite reference spectra (Schlegel et al, 2001).…”

Section: Formation and Structure Of Layered Zn-precipitatesmentioning

confidence: 99%

Formation of Zn-rich phyllosilicate, Zn-layered double hydroxide and hydrozincite in contaminated calcareous soils

Jacquat

Voegelin

Villard

et al. 2008

Geochimica et Cosmochimica Acta

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Recent studies demonstrated that Zn-phyllosilicate-and Zn-layered double hydroxide-type (Zn-LDH) precipitates may form in contaminated soils. However, the influence of soil properties and Zn content on the quantity and type of precipitate forming has not been studied in detail so far. In this work, we determined the speciation of Zn in six carbonate-rich surface soils (pH 6.2 to 7.5) contaminated by aqueous Zn in the runoff from galvanized power line towers (1322 to 30090 mg/kg Zn). Based on 12 bulk and 23 microfocused extended X-ray absorption fine structure (EXAFS) spectra, the number, type and proportion of Zn species were derived using principal component analysis, target testing, and linear combination fitting. Nearly pure Zn-rich phyllosilicate and Zn-LDH were identified at different locations within a single soil horizon, suggesting that the local availabilities of Al and Si controlled the type of precipitate forming. Hydrozincite was identified on the surfaces of limestone particles that were not in direct contact with the soil clay matrix. With increasing Zn loading of the soils, the percentage of precipitated Zn increased from ~20% to ~80%, while the precipitate type shifted from Zn-phyllosilicate and/or Zn-LDH at the lowest studied soil Zn contents over predominantly Zn-LDH at intermediate loadings to hydrozincite in extremely contaminated soils. These trends were in agreement with the solubility of Zn in equilibrium with these phases. Sequential extractions showed that large fractions of soil Zn (~30% to ~80%) as well as of synthetic Zn-kerolite, Zn-LDH, and hydrozincite spiked into uncontaminated soil were readily extracted by 1 M NH 4 NO 3 followed by 1 M NH 4 -acetate at pH 6.0. Even though the formation of Zn precipitates allows for the retention of Zn in excess to the adsorption capacity of calcareous soils, the long-term immobilization potential of these precipitates is limited.3

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Evidence for the nucleation and epitaxial growth of Zn phyllosilicate on montmorillonite

Cited by 73 publications

References 59 publications

Soil properties controlling Zn speciation and fractionation in contaminated soils

Soil properties controlling Zn speciation and fractionation in contaminated soils

Zinc speciation in mining and smelter contaminated overbank sediments by EXAFS spectroscopy

Formation of Zn-rich phyllosilicate, Zn-layered double hydroxide and hydrozincite in contaminated calcareous soils

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