Laser ablation of aluminosilicates: Comparison between allophane and mixed alumina/silicas by Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry

Castello, J.; Gaumet, Jean‐Jacques; Müller, Jean-François; Derousseaux, S.; Guilment, Jean; Poncelet, Olivier

doi:10.1016/j.apsusc.2007.02.084

Cited by 5 publications

(2 citation statements)

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“…Figure 5 presents the calculated Raman spectrum of a hydrated model structure and compares it with an experimental FT-Raman spectrum of a synthetic allophane sample. 32 The sample was obtained by the TEOS synthesis procedure 33,34 that yields allophane particles of homogeneous size and shape and having a small number of defects. The sample was characterized by a Si/Al ratio of 0.56 with ca.…”

Section: Structure and Dynamics Of Allophanementioning

confidence: 99%

Structural Model and Computer Modeling Study of Allophane

et al. 2007

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A model of an allophane nanoball is proposed. The model structure is characterized by a Si/Al ratio of 0.49, has external and internal diameters of 50 and 40 Å, respectively, and contains six holes of about 7 Å size connecting the internal void of the nanoball with external space. The calculated XRD pattern and Raman spectrum of the structure are in a good agreement with the corresponding experimental data. Molecular dynamics calculations of hydrated allophane have shown that the model reproduces the main experimental findings such as the adsorption of water molecules in the void of allophane or the exchange between the “internal” and “external” water. The adsorption of water molecules occurs mostly in the regions with negative electrostatic potential, where the molecules find an environment close to that in bulk liquid water that explains the high water retention by this aluminosilicate. The allophane model can be used as a basis in further refinements of its structure as well as in molecular modeling studies of this aluminosilicate.

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Section: Structure and Dynamics Of Allophanementioning

confidence: 99%

Structural Model and Computer Modeling Study of Allophane

et al. 2007

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“…During purification, the unique pore structure of Allo is readily destroyed via irreversible aggregation (also referred to as shrinking [21]) of particles upon drying, which largely decreases the porosity and SSA of Allo. Synthesized high-purity Allo can be produced in large amounts but readily undergoes irreversible aggregation during drying even if freeze-drying is used [22,23]. This irreversible aggregation results mainly from capillary stress in the inner cavity of unsaturated Allo [21], which represents the net interparticle stress that tends to pull one particle to another [24].…”

Section: Introductionmentioning

confidence: 99%

Tailoring structure and surface chemistry of hollow allophane nanospheres for optimization of aggregation by facile methyl modification

Thill

Yuan

et al. 2020

Applied Surface Science

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Allophane, an earth-abundant and easy-to-be-synthesized hollow nanospherical material, readily loses its unique pore structure via irreversible aggregation of particles upon drying, which mainly results from capillary stress in the unsaturated inner cavity. To tackle this problem, we develop a strategy for tailoring the capillary stress and thus the aggregation state of allophane by introducing methyl moieties onto the inner surface during preparation. Combined spectroscopic results verified the formation of methyl-allophane with methyl groups only on its inner surface. The presence of a reflection at approximately 33 Å in the X-ray diffraction pattern, ascribed to the interference between particles, indicated an increased structural order in methyl-allophane. The thermal analysis data revealed a decrease of the inner-surface hydrophilcity. The Brunauer-Emmett-Teller (BET) specific surface area increased from 269 to 523 m 2 /g after methyl modification. An aggregation model, in contrast with that of allophane, was proposed based on the microscopic and small-angle X-ray scattering results to explain these observed changes. This work exhibited that substitution of silanol by methyl on the inner surface of allophane leads to improvement of structural order by eliminating the presence of oligomeric silicates and decreases the hydrophilicity, resulting in the reduction of the capillary stress in the inner cavity and thus the inhibition of irreversible aggregation of particles during drying. The insight into the mechanisms underneath the above mentioned changes upon methyl modification unraveled in this work is helpful for addressing the common aggregation issue of other nanomaterials.

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Laser Ionization Mass Spectrometry of Inorganic Ions

Pavlov

Attygalle

2012

Mass Spectrometry Handbook

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Laser ablation of aluminosilicates: Comparison between allophane and mixed alumina/silicas by Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry

Cited by 5 publications

References 13 publications

Structural Model and Computer Modeling Study of Allophane

Structural Model and Computer Modeling Study of Allophane

Tailoring structure and surface chemistry of hollow allophane nanospheres for optimization of aggregation by facile methyl modification

Laser Ionization Mass Spectrometry of Inorganic Ions

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