Thermogravimetric and kinetic analysis of thermal decomposition characteristics of microbial calcites induced by cyanobacteria Synechocystis sp. PCC6803

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• 作者：Zuozhen Han ; Dingxiang Zhuang ; Huaxiao Yan&#8230
• 关键词：Thermal decomposition ; Calcium carbonate ; Microbial calcite ; TG–DTG–DSC ; Kinetics ; Synechocystis sp. PCC6803
• 刊名：Journal of Thermal Analysis and Calorimetry
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：127
• 期：2
• 页码：1371-1379
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Physical Chemistry; Analytical Chemistry; Polymer Sciences; Inorganic Chemistry; Measurement Science and Instrumentation;
• 出版者：Springer Netherlands
• ISSN：1588-2926
• 卷排序：127

文摘

Although various complicated methods have always been made attempts, it is still well difficult to efficiently distinguish between the biogenic and abiogenic minerals in geological area up to now. In present study, the thermal decomposition unique characteristics of microbial calcites (MC), induced by cyanobacteria Synechocystis sp. PCC6803, were compared with those of chemical calcites (CC) prepared by the reaction of sodium carbonate (Na₂CO₃) with calcium chloride (CaCl₂). Two samples were firstly analyzed by scanning electron microscope and X-ray diffraction, and were further investigated thermal decomposition behaviors using a thermogravimetric analyzer at different heating rates of 278.15, 283.15, 293.15, and 303.15 K min−1 from 323.15 to 1273.15 K, respectively, then kinetic parameters were calculated via Popescu, Kissinger–Akahira–Sunose, and Flynn–Wall–Ozawa methods, and then the kinetics mechanism functions were deduced by Popescu method. The results showed that these two kinds of precipitates were actually both calcite crystals although the surface morphologies were quite different. Whereas thermal decomposition kinetics mechanism function of MC can be described as Avrami–Erofeev equation ([−ln(1 − α)]1/3), while CC corresponded to Contracting sphere (volume) ([1 − (1 − α)]1/3), the results also showed that the average activation energy of MC and CC was 217.9 and 170.5 kJ mol−1, respectively; that is, MC has higher thermal stability, which should be originated from the inducing effects and the different precipitation conditions provided by Synechocystis sp. PCC6803. These above results provided useful information not only for efficiently distinguishing between the biogenic and abiogenic minerals in geological area, and also for better understanding the microbial mineralization.