Chemical and Biotechnology |
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Study on the thermal decomposition kinetics of nano-sized calcium carbonate |
LI Dai-xi, SHI Hong-yun, DENG Jie, XU Yuan-zhi |
Chemistry Department, Guizhou University, Guizhou 550025, China; Chemistry Department, Zhejiang University, Hangzhou 310027, China |
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Abstract This study of the thermal decomposition kinetics of various average diameter nano-particles of calcium carbonate by means of TG-DTA(thermogravimetry and differential thermal analysis) showed that the thermal decomposition kinetic mechanisms of the same crystal type of calcium carbonate samples do not vary with decreasing of their average diameters; their pseudo-active energy Ea; and that the top-temperature of decomposition Tp decreases gently in the scope of micron-sized diameter, but decreases sharply when the average diameter decreases from micron region to nanometer region. The extraordinary properties of nano-particles were explored by comparing the varying regularity of the mechanisms and kinetic parameters of the solid-phase reactions as well as their structural characterization with the variation of average diameters of particles. These show that the aggregation, surface effect as well as internal aberrance and stress of the nano-particles are the main reason causing both Ea and Tp to decline sharply with the decrease of the average diameter of nano-particles.
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Received: 08 October 2002
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