Kaolinite to halloysite-7 angstrom transformation in the kaolin deposit of Sao Vicente de Pereira, Portugal

• Tipo: Artigo em Revista Científica Internacional
• Data: 2001

Autores

Bobos, I (Autor) FCUP; Duplay, J (Autor) Outra; Rocha, J (Autor) Outra; Gomes, C (Autor) Outra

Revista

Título: Clays and Clay Minerals

Vol. 49

Páginas: 596-607

ISSN: 0009-8604

Editora: Springer Nature

Indexação

ISI Web of Knowledge - 61 Citações

Scopus - 70 Citações

Classificação Científica

FOS: Ciências agrárias > Agricultura, silvicultura e pescas

Outras Informações

ID Authenticus: P-000-SGP

DOI: 10.1346/ccmn.2001.0490609

Abstract (EN): 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.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 12