Crystal chemistry of trace elements in natural and synthetic goethite

Manceau, Alain; Schlegel, Michel L.; Musso, Maurizio; Solé, Vicente Armando; Gauthier, C.; Petit, P.; Trolard, Fabienne

doi:10.1016/s0016-7037(00)00427-0

Cited by 256 publications

(184 citation statements)

References 82 publications

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“…Typically, the interatomic distance of edge-sharing linkage is shorter than that of corner-sharing linkage [49]. The EXAFS analysis results (Table 4) show that there are two detectable linkage modes between the adsorbed Zn(II) ions and the neighboring atom Ti, corresponding to two average Zn-Ti bond lengths of 3.24 ± 0.01 Å (n = 3) and 3.69 ± 0.01 Å (n = 3), respectively.…”

Section: The Microscopic Structure Of Adsorbed Zn(ii)mentioning

confidence: 99%

EXAFS studies on adsorption irreversibility of Zn(II) on TiO2: Temperature dependence

Pan

Zhang

et al. 2008

Journal of Colloid and Interface Science

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Adsorption irreversibility of Zn(II) on TiO 2 at various temperatures was studied using a combination of classical macroscopic methods and extended X-ray absorption fine structure (EXAFS) spectroscopy. When the temperature was increased from 5 to 40 • C, the Zn(II) adsorption capacity increased by 130%, and adsorbed Zn(II) became more reversible. The standard Gibbs free energy change ( G 0 ) of the adsorption reaction at 5, 20, and 40 • C was determined to be −19.58 ± 0.30, −22.28 ± 0.10, and −25.14 ± 0.21 kJ mol −1 , respectively. And the standard enthalpy ( H 0 ) and entropy ( S 0 ) were 24.55 ± 2.91 kJ mol −1 and 159.13 ± 0.53 J mol −1 K −1 , respectively. EXAFS spectra results showed that the hydrated Zn(II) was adsorbed through fourfold coordination with an average Zn-O bond distance of 1.98 ± 0.01 Å. Two Zn-Ti atomic distances of 3.25 ± 0.02 and 3.69 ± 0.03 Å were observed, which corresponded to an edge-sharing linkage mode (strong adsorption) and a cornersharing linkage mode (weak adsorption), respectively. As the temperature increased from 5 to 40 • C, the number of strong adsorption sites (N 1 ) remained relatively constant while the number for the weak adsorption sites (N 2 ) increased by 31%. These results indicate that the net gain in adsorption capacity and the decreased adsorption irreversibility at elevated temperatures were due to the increase in available weak adsorption sites (N 2 ) or the decrease in the ratio of N 1 /N 2 . Both the macroscopic sorption/desorption equilibrium data and the molecular level evidence of this study suggest that in a given environmental system (e.g., soils or natural waters) zinc and other similar heavy metals are likely more mobile at higher temperatures.

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Section: The Microscopic Structure Of Adsorbed Zn(ii)mentioning

confidence: 99%

EXAFS studies on adsorption irreversibility of Zn(II) on TiO2: Temperature dependence

Pan

Zhang

et al. 2008

Journal of Colloid and Interface Science

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“…The congruent dissolution of Al, Cr and V with Fe for the majority of samples suggests that these elements are in the structure of goethite and hematite. These metals are known to substitute for Fe 3+ in the structures of goethite and hematite (Trolard et al 1995;Manceau et al 2000;Wells et al 2001;Singh et al 2002;Perrier et al 2006). Aluminium substitution in hematite, the main Fe oxide, in sample Ci (Table 2) was very low but total Al was much higher than in the other samples (Table 3), which suggest that most of the Al in sample Ci was not present in the structure of Fe oxides.…”

Section: Relationships Between Trace Elements and Soil Fe Oxides Basementioning

confidence: 94%

Association of trace elements and dissolution rates of soil iron oxides

et al. 2014

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Abstract. In this study, nine Oxisols and five Ultisols from Thailand were used to determine the association of major and trace elements with iron (Fe) oxides. The Fe oxides were concentrated and the association of elements (Al, Ca, Cu, Cr, Mg, Mn, Ni, Pb, P, Si, V, Ti, Zn) with Fe was evaluated using batch dissolution in 1 M HCl at 208C. The dissolution behaviour of Fe oxide concentrates was determined using batch dissolution and flow-through reactors. In addition to Fe, both Al and Ti were present in significant amounts in the Fe oxide concentrates. Manganese was the most abundant trace element, and Cu, Zn, Pb and As concentrations were <250 mg kg -1 in most samples. The dissolution behaviour of Fe-oxide concentrates indicated that Al, Cr and V were mostly substituted for Fe 3+ in the structure of goethite and hematite. A significant proportion of Mn, Ni, Co, Pb and Si was also present within the structure of these minerals. Some Mg, Cu, Zn, Ti and Ca was also associated with Fe oxides. The dissolution kinetics of Fe oxide concentrates was well described by three models, i.e. the cube root law, Avrami-Erofejev equation and Kabai equation, with the dissolution rate constants (10 3 k) corresponding to the three models ranging from 0.44 to 6.11 h -1 , from 1.01 to 4.40 h -1 and from 0.03 to 4.12 h -1 , respectively. The k constants of Fe oxide concentrates in this study were significantly and negatively correlated with the mean crystal dimension derived from [110] and [104] of hematite, the dominant mineral in most samples. The steady-state dissolution rate of a soil Fe-oxide concentrate (sample Kk) was substantially higher than for synthetic goethite under highly acidic conditions; this is possibly due to the greater specific surface area of sample Kk than the synthetic goethite.Additional keywords: acid dissolution, batch method, Fe oxide concentrate, non-stirred flow through reactor method, total element concentration, tropical red soils.

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“…In the technology of digital image processing, the measurement of the area of a target objective includes the measurement of its interior and boundary points [11][12][13][14][15]. In binary images, the enclosed area is composed of sets of interconnected black pixels in a great number, so the calculation of the number of black pixels in this enclosed area is to solve the area of the object region.…”

Section: Pixel Counting Methodsmentioning

confidence: 99%

“…Because in the technology of digital image processing, a pixel is used as the basic unit for image processing, to make more accurate analysis of actual cells, we must convert pixel values into micron. In terms of the international system of units: 1 inch = 25400 microns [77-78], we can get the following method for unit conversion: (15) In the formula (15), and are the value of sliced cells and the displayed value of microscopic sliced images, respectively. is the number of pixels on an inch of the monitor screen, and is the enlarged times of cell images.…”

Section: Table 4 Tangential Wall/anticlinal Wall Thickness Computingmentioning

confidence: 99%

Research on the Method for Extracting the Cellular Microscopic Digital Features of Coniferous Wood

Zhao¹,

Wang²

2015

IJUNESST

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Crystal chemistry of trace elements in natural and synthetic goethite

Cited by 256 publications

References 82 publications

EXAFS studies on adsorption irreversibility of Zn(II) on TiO2: Temperature dependence

EXAFS studies on adsorption irreversibility of Zn(II) on TiO2: Temperature dependence

Association of trace elements and dissolution rates of soil iron oxides

Research on the Method for Extracting the Cellular Microscopic Digital Features of Coniferous Wood

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