| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Bobos, Iuliu
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Publications (4/4 displayed)
- 2017The Application of Functionalized Pillared Porous Phosphate Heterostructures for the Removal of Textile Dyes from Wastewatercitations
- 2015Morphological and Chemical Characterization of Mineral Concretions in the Freshwater Bivalve Anodonta cygnea (Unionidae)citations
- 2001Kaolinite to halloysite-7 angstrom transformation in the kaolin deposit of Sao Vicente de Pereira, Portugalcitations
- 2000Dissolution of K-feldspar into Si-Al gel and crystallization of halloysite identified in the kaolin deposit of Sao Vicente de Pereira (Portugal)
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article
Kaolinite to halloysite-7 angstrom transformation in the kaolin deposit of Sao Vicente de Pereira, Portugal
Abstract
The transformation of kaolinite to halloysite-7 Angstrom was identified in the kaolin deposit of Sao Vicente de Pereira (SVP), using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Both the 02,11 and 13,13 reflections show changes in the XRD patterns along the kaolinite to halloysite-7 A transition, and the FTIR spectra show changes corresponding to both OH- and Si-O-stretching bands and Al-O-Si-bending vibrations. The interlayer water content in the kaolinite structure increases during transition. The two-layer periodicity of well-ordered kaolinite and rolling up of kaolinite plates are observed using high-resolution transmission electron microscopy (HRTEM). Long and short tubes exhibit halloysite-7 Angstrom. No structural Fe was found in the kaolinite samples. Analytical electron microscopy (AEM) indicates no substitution of Al3+ for Si4+. The Si/Al ratio shows values of similar to1 for the kaolinite and rolled kaolinite plates. The Al-27 magic angle spinning neutron magnetic resonance (MAS-NMR) spectra display a resonance centered at similar to1 ppm, assigned to six-coordinated aluminum. The transformation of kaolinite to halloysite-7 Angstrom is controlled by surface reaction.