Microstructural Properties of Natural Allophane/Gibbsite from a White Bauxite Deposit in Montenegro

IF 0.7 4区化学 Q4 CHEMISTRY, MULTIDISCIPLINARY

Croatica Chemica Acta Pub Date : 2018-01-02 DOI:10.5562/CCA3276

M. Ristić, S. Krehula, S. Musić

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引用次数: 4

Abstract

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.

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黑山白铝土矿中天然Allophane/Gibbsite的微观结构特征

研究了黑山白铝土矿的微观结构特征。XRD分析表明存在脲基甲酸（Al2O3·2SiO2·3H2O）和三水铝石（γ-Al（OH）3）。脲基甲酸相显示出非常宽的衍射线，因此表明该相中结晶度差以及非常细的纳米颗粒。在1000°C下加热天然脲基甲酸酯/三水铝石后，形成了莫来石（Al6Si2O13），但结晶度较低。对脲醛树脂、三水铝石和莫来石的红外光谱进行了分析。天然脲原纸/三水铝石的FE-SEM图像显示出主要的无定形样形态。在加热天然脲基甲酸酯/三水铝石时，可见二维（2D）微观结构。EDS分析显示有微量钙、钾、镁和铁。由于赤铁矿的存在，铁迹的57Fe Mössbauer谱显示出较小的相对强度磁分裂分量，并且由于八面体位置中取代Al3+的Fe3+离子和/或赤铁矿颗粒的超顺磁性部分的存在，显示出中心四极双峰。探讨了黑山白色铝土矿形成的可能地球化学机制。

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来源期刊

Croatica Chemica Acta 化学-化学综合

CiteScore

0.60

自引率

0.00%

发文量

审稿时长

18 months

期刊介绍： Croatica Chemica Acta (Croat. Chem. Acta, CCA), is an international journal of the Croatian Chemical Society publishing scientific articles of general interest to chemistry.