Basal plane reactivity of phyllosilicates studied in situ by hydrothermal atomic force microscopy (HAFM)

Aldushin, Kirill; Jordan, Guntram; Schmahl, Wolfgang W.

doi:10.1016/j.gca.2006.04.015

Cited by 39 publications

(37 citation statements)

References 16 publications

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“…Pits have circular form and appear randomly distributed over the surface. This confirms previous work on silicate alteration (Zuddas and Michard, 1993;Murakami et al, 2002;Aldushin et al, 2006), where dissolution effects on the surface state were found from the very early stages of the process. However, the relationship between the measured dissolution fluxes and surface changes is unclear.…”

Section: Evolution Of the Surface Statesupporting

confidence: 91%

Influence of pH and temperature on the early stage of mica alteration

Pachana¹,

Zuddas²,

Censi³

2012

Applied Geochemistry

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a b s t r a c tMineral dissolution and precipitation reactions actively participate in controlling fluid chemistry during water-rock interaction. In this study, the changes in the biotite and muscovite basal surface nano-morphology were evaluated during interaction with fluids of different pH (pH = 1.1, 3.3 and 5.7) at different temperatures (T = 25°, 120°, and 200°C). Results show that at the nanometre scale resolution of the atomic force microscope (AFM), dissolution generates etch pits with a stair-shaped pattern over the (0 0 1) surface. The flux of dissolved elements decreases when pH increases. However, at pH 5.7, a change was found in the flux after 42 h of reaction when abundant gibbsite and kaolinite coat the dissolving mineral surface. This phenomenon was widely observed at edges of the etch pits by AFM. It was also found that an increase in temperature produces an enhancement in the elemental flux in both micas. Dissolution regime changes after less than one day of interaction at high temperature because of abundant coating formation over the etch pits and edges. The results demonstrate the key role of nanometre size neogenic phases in the control of elemental flux from mica surfaces to solution. The formation of nanometre size coatings, blocking the sites active for dissolution, appears to control the alteration of phyllosilicates even at the early stage of the interaction.

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Section: Evolution Of the Surface Statesupporting

confidence: 91%

Influence of pH and temperature on the early stage of mica alteration

Pachana¹,

Zuddas²,

Censi³

2012

Applied Geochemistry

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“…S5, Table 1), demonstrating the importance of grain geometry on the overall dissolution rate. Like biotite, other sheet silicates have been shown to primarily dissolve parallel to the basal surface, i.e., at the (h k 0) surfaces (Kaviratna and Pinnavaia, 1994;Turpault and Trotignon, 1994;Bosbach et al, 2000;Bickmore et al, 2001Bickmore et al, , 2003Aldushin et al, 2006;Hodson, 2006;Saldi et al, 2007;Cappelli et al, 2013).…”

Section: Surface Area and Dissolutionmentioning

confidence: 99%

The effect of pH, grain size, and organic ligands on biotite weathering rates

Bray

Oelkers

Bonneville

et al. 2015

Geochimica et Cosmochimica Acta

104

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Biotite dissolution rates were determined at 25°C, at pH 2-6, and as a function of mineral composition, grain size, and aqueous organic ligand concentration. Rates were measured using both open-and closed-system reactors in fluids of constant ionic strength. Element release was non-stoichiometric and followed the general trend of Fe, Mg > Al > Si. Biotite surface area normalised dissolution rates (r i ) in the acidic range, generated from Si release, are consistent with the empirical rate law:where k H,i refers to an apparent rate constant, a H þ designates the activity of protons, and x i stands for a reaction order with respect to protons. Rate constants range from 2.15 Â 10 À10 to 30.6 Â 10 À10 (moles biotite m À2 s À1 ) with reaction orders ranging from 0.31 to 0.58. At near-neutral pH in the closed-system experiments, the release of Al was stoichiometric compared to Si, but Fe was preferentially retained in the solid phase, possibly as a secondary phase. Biotite dissolution was highly spatially anisotropic with its edges being $120 times more reactive than its basal planes. Low organic ligand concentrations slightly enhanced biotite dissolution rates. These measured rates illuminate mineral-fluid-organism chemical interactions, which occur in the natural environment, and how organic exudates enhance nutrient mobilisation for microorganism acquisition.

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“…SiO 2 measurement of process rates and energies alongside information on changes in surface topography at the atomic scale (Aldushin et al, 2006;Bosbach et al, 2000;Gratz et al, 1991;Li et al, 2014;Simon et al, 2011). All height and phase contrast images of boiling HNO 3 , hot HCl and NaTPB extracted mineral samples were collected under ambient laboratory conditions in tapping mode with AFM (Dimension Edge, Bruker).…”

Section: Micasmentioning

confidence: 99%