IngentaConnect 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

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: 10.1346/CCMN.2006.0540602

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