Hydrothermal synthesis of Mg-rich and Mg-Ni-rich kaolinite

Authors: Bentabol, Maria; Cruz, Maria Dolores Ruiz; Huertas, Francisco Javier; Linares, Jose

Source: Clays and Clay Minerals, Volume 54, Number 6, December 2006 , pp. 667-677(11)

Publisher: The Clay Minerals Society

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Abstract:

Mg-rich kaolinite and Mg+Ni-rich kaolinite have been synthesized in hydrothermal experiments (200 and 400°C) from poorly crystalline kaolinite and Mg- and Mg+Ni-bearing solutions. Al-rich serpentine and Al-rich chlorite were obtained as sub-products of the reactions. The formation of these phases occurred through a dissolution-precipitation mechanism that led to spherical kaolinite after short reaction times. A morphological evolution towards platy particles and stacks occurred at increasing run times.

Identification of the several phases was carried out using a combination of X-ray diffraction and transmission/analytical electron microscopy. Analytical data indicate that the Mg content in kaolinite increased as a function of the reaction time and temperature, reaching up to 0.46 atoms per half formula unit (a.p.h.f.u.). The measured (Mg+Ni) content reached up to 0.56 a.p.h.f.u.. Both the gradual increase of the b-cell parameter of kaolinite at increasing Mg contents and the presence of new bands on the FTIR spectra of the synthesized kaolinite point to a Mg-for-Al replacement in the octahedral sheet rather than to the presence of serpentine-like layers interstratified in the kaolinite structure.

Keywords: AL-RICH SERPENTINE; FTIR; HYDROTHERMAL SYNTHESIS; MG-RICH KAOLINITE; TEM/AEM; XRD

Document Type: Research article

DOI: http://dx.doi.org/10.1346/CCMN.2006.0540602

Publication date: 2006-12-01

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The JOURNAL publishes articles of interest to the international community of clay scientists, including but not limited to areas in mineralogy, crystallography, geology, geochemistry, sedimentology, soil science, agronomy, physical chemistry, colloid chemistry, ceramics, petroleum engineering, foundry engineering, and soil mechanics. Clays and Clay Minerals exists to disseminate to its worldwide readership the most recent developments in all of these aspects of clay materials. Manuscripts are welcome from all countries.
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Hydrothermal synthesis of Mg-rich and Mg-Ni-rich kaolinite

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