Vaterite growth and dissolution in aqueous solution .3. Kinetics of transformation
Vaterite growth and dissolution in aqueous solution .3. Kinetics of transformation
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DOI：
10.1016/s0022-0248(96)01128-1
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发表时间：
1997-06-01
影响因子：
1.8
通讯作者：
Kontrec, J
中科院分区：
文献类型：
--
作者：
Kralj, D;Brecevic, L;Kontrec, J
在温度为25 ℃ ~ 45 ℃、离子强度为15 ~ 415 mmol dm（-3）的条件下，研究了球文石在水溶液中向方解石转化的动力学。球文石和方解石都自发沉淀，球文石最初是系统中唯一的固相。通过记录pH作为时间的函数来跟踪转化的进程。结果发现，这种转变是溶液介导的，方解石的生长是速率控制过程。这一结论还得到了数学模型的支持，该模型用于预测整个过程中固相和溶液的变化。该模型是基于速率常数和机制的过程中所涉及的转变，以及实验确定的数密度的晶体formed.The方解石的种子生长动力学在单独的实验中确定，在10摄氏度和55摄氏度之间的温度，和速率定律被发现是抛物线。得到的与温度有关的速率常数E-a = 55.29 kJ mol（-1）的高活化能支持了方解石生长受晶体表面过程控制的假设。
The kinetics of transformation of vaterite to calcite in aqueous solution was studied at temperatures between 25 degrees C and 45 degrees C and ionic strengths between 15 and 415 mmol dm(-3). Both vaterite and calcite precipitated spontaneously, with vaterite being initially the only solid phase in the system. The progress of the transformation was followed by recording pH as a function of time. It was found that this transformation was solution-mediated, and that the growth of calcite was the rate-determining process. This conclusion was additionally supported by a mathematical model made to predict changes of both the solid phase and the solution during the overall process. The model is based on the rate constants and the mechanism of the processes involved in the transformation, as well as on the experimentally determined number density of the crystals formed.The seeded growth kinetics of calcite was determined in separate experiments, at temperatures between 10 degrees C and 55 degrees C, and the rate law was found to be parabolic. The high activation energy obtained for the temperature dependent rate constants E-a = 55.29 kJ mol(-1), supports the assumption that the calcite growth was controlled by processes at the crystal surface.