Thermogravimetric analysis–mass spectrometry (TGA–MS) of hydromagnesite from Dujiali Lake in Tibet, China
Thermogravimetric analysis–mass spectrometry (TGA–MS) of hydromagnesite from Dujiali Lake in Tibet, China
复制标题
中国西藏杜家丽湖水菱镁矿的热重分析-质谱分析 (TGA-MS)
DOI：
10.1007/s10973-018-7197-8
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发表时间：
2018
影响因子：
4.4
通讯作者：
Power Ian M.
中科院分区：
文献类型：
--
作者：
Lin Yongjie;Zheng Mianping;Ye Chuanyong;Power Ian M.
采用热重-质谱联用、原位X射线衍射、扫描电镜和傅里叶变换红外光谱等方法对西藏杜家里湖水菱镁矿[Mg 5（CO 3）4（OH）2. 4 H2O]进行了表征。本研究描述了水菱镁矿在不同的加热速率和氦气（He）或二氧化碳（CO2）气氛下的热分解机制的变化。在He气氛中，只观察到两个分解阶段;结晶水的损失，然后是组合的脱羟基和脱碳酸。然而，在CO2气氛下，脱羟基和脱碳分别发生，因为惰性CO2气体防止水菱镁矿的MgCO 3组分分解。总的来说，热分解是一个吸热过程。一个明显的放热过程发生在约540 °C的条件下，高分压的CO2或高加热速率，并意味着结晶的菱镁矿（MgCO 3）。推测水菱镁矿晶体结构中复杂的氢键和不同的碳酸根基团是水菱镁矿不同阶段释放H2O和CO2的主要原因。
Thermogravimetric analysis–mass spectrometry, in situ X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy were used to characterize hydromagnesite [Mg5(CO3)4(OH)2·4H2O] from Dujiali Lake in Tibet, China. This study describes the variations in the thermal decomposition mechanisms of hydromagnesite at varying heating rates and under either helium (He) or carbon dioxide (CO2) atmospheres. In a He atmosphere, only two decomposition stages were observed; the loss of the crystalline water followed by the combined dehydroxylation and decarbonation. However, under a CO2atmosphere, the dehydroxylation and decarbonation occur separately as the inert CO2gas prevents the decomposition of the MgCO3component of hydromagnesite. Overall, the thermal decomposition is an endothermic process. A distinctly exothermic process occurs at about 540 °C under conditions of high partial pressure of CO2or high heating rate and implies the crystallization of magnesite (MgCO3). We propose that the release of H2O and CO2at different stages likely results from the complicated hydrogen bonds and different carbonate groups in the crystal structure of hydromagnesite.