Model-free treatment of the dehydration kinetics of nedocromil sodium trihydrate.
Model-free treatment of the dehydration kinetics of nedocromil sodium trihydrate.
复制标题
奈多罗米钠三水合物脱水动力学的无模型处理。
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
D. Grant
中科院分区：
文献类型：
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作者：
Deliang Zhou;E. Schmitt;Geoff G. Z. Zhang;D. Law;C. Wight;S. Vyazovkin;D. Grant
动力学分析的传统模型拟合方法假设整个反应过程中存在固定机制，因此对于许多固态反应来说可能过于简单。即使对于具有固定机制的反应，模型拟合有时也无法唯一地识别反应模型。另一种无模型方法足够灵活，可以在反应过程中改变机制，因此为固态反应动力学提供了更现实的处理。使用奈多罗米钠三水合物的两个连续脱水反应研究了无模型分析在固态脱水中的应用。每次脱水过程中活化能的变化说明了此类反应的复杂性。第一步脱水遵循一维相界动力学，直到脱水分数达到 0.75，此后偏离该模型。第二步脱水遵循二维和三维扩散之间的中间机制，无法用任何常见模型来描述。对于理解这些固态脱水反应的细节，无模型方法显然比模型拟合方法更好。
The conventional model-fitting approach to kinetic analysis assumes a fixed mechanism throughout the reaction and therefore may be too simplistic for many solid-state reactions. Even for a reaction with a fixed mechanism, model fitting sometimes cannot identify the reaction model uniquely. The alternative model-free approach is sufficiently flexible to allow for a change of mechanism during the course of a reaction and therefore provides a more realistic treatment of solid-state reactions kinetics. The application of model-free analysis to solid-state dehydrations was investigated using the two consecutive dehydration reactions of nedocromil sodium trihydrate. The complexity of such reactions is illustrated by the variation of the activation energy as each dehydration proceeds. The 1st-step dehydration follows one-dimensional phase boundary kinetics until the fraction dehydrated reaches 0.75, and deviates from this model thereafter. The 2nd-step dehydration follows a mechanism intermediate between two- and three-dimensional diffusion that cannot be described by any of the common models. The model-free approach is clearly better than the model-fitting approach for understanding the details of these solid-state dehydration reactions.