عنوان المقالة:Prediction of the metastable zone in “CaCO3-CO2-H2O” system Prediction of the metastable zone in “CaCO3-CO2-H2O” system
حمزة الفيل | Hamza Elfil | 3967
نوع النشر
مجلة علمية
المؤلفون بالعربي
حمزة الفيل، هونري روك
المؤلفون بالإنجليزي
Hamza Elfil, Henri Roques
الملخص العربي
The surpassing of the solubility product of the anhydrous forms of calcium carbonate calcite, aragonite, and vaterite is not sufficient to induce spontaneous precipitation. The existence of a metastable zone, in the nucleation of the calcium carbonate, is still an experimental phenomenon. A thermodynamic demarcation of the metastable zone in the “CaCO3–CO2–H2O” system, where only a secondary nucleation can occur, has been delimited for the first time. Through experimental exploration of a large supersaturation field, results obtained by the bubbling method are treated with the use of thermodynamic data of different varieties of CaCO3. At temperatures ranging between 25 and 60°C, a primary nucleation (spontaneous precipitation) occurs when the ionic activity product of the calco– carbonic solution surpasses the solubility product of CaCO3_H2O. No spontaneous nucleation occurs when the ionic activity product stabilizes between the solubility products of calcite and monohydrated calcium carbonate, which means that the solution remains in a metastable state. The metastability can be broken by seeding with calcium carbonate crystals (aragonite in this case) and then the germination is a secondary one. A model for the prediction of the limit of the metastable zone, presented in this report, is in agreement with experimental results.
تاريخ النشر
24/08/2004
الناشر
AIChE Journal
رقم المجلد
5
رقم العدد
8
رابط DOI
DOI: 10.1002/aic.10160
الصفحات
1908-1916
رابط الملف
تحميل (149 مرات التحميل)
الكلمات المفتاحية
metastability, secondary nucleation, crystallization, Monohydrated calcium carbonate, calcite
رجوع