Croatica Chemica Acta, Vol. 91 No. 1, 2018.
Izvorni znanstveni članak
https://doi.org/10.5562/cca3276
Microstructural Properties of Natural Allophane/Gibbsite from a White Bauxite Deposit in Montenegro
Mira Ristić
; Division of Materials Chemistry, Ruđer Bošković Institute, P.O. Box 180, HR-10002, Zagreb, Croatia
Stjepko Krehula
; Division of Materials Chemistry, Ruđer Bošković Institute, P.O. Box 180, HR-10002, Zagreb, Croatia
Svetozar Musić
; Division of Materials Chemistry, Ruđer Bošković Institute, P.O. Box 180, HR-10002, Zagreb, Croatia
Sažetak
Microstructural properties of white bauxite from Montenegro were investigated. XRD analysis showed the presence of allophane (Al2O3 · 2SiO2 · 3H2O) and gibbsite (γ-Al(OH)3). The allophane phase showed very broadened diffraction lines, thus indicating poor crystallinity as well as very fine nanoparticles in this phase. Upon heating of natural allophane/gibbsite at 1000 °C mullite (Al6Si2O13) was formed, but with a lower degree of crystallinity. FT-IR spectra of allophane, gibbsite and mullite were interpreted. FE-SEM images of natural allophane/gibbsite showed a dominantly amorphous-like morphology. Upon heating of natural allophane/gibbsite two-dimensional (2D) microstructure was visible. EDS analysis showed traces of calcium, potassium, magnesium and iron. The 57Fe Mössbauer spectrum of iron traces showed a small relative intensity magnetic splitting component due to the presence of hematite and a central quadrupole doublet due to the presence of Fe3+ ions substituted for Al3+ in octahedral positions and/or a superparamagnetic fraction of hematite particles. The possible geochemical mechanism of white bauxite formation in Montenegro is discussed.
This work is licensed under a Creative Commons Attribution 4.0 International License.
Ključne riječi
allophane; gibbsite; white bauxite, Montenegro
Hrčak ID:
195341
URI
Datum izdavanja:
2.1.2018.
Posjeta: 1.613 *