کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5373342 1504211 2015 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Molecular dynamics study of montmorillonite crystalline swelling: Roles of interlayer cation species and water content
ترجمه فارسی عنوان
مطالعه دینامیک مولکولی تورم بلورین مونتموریلونیت: نقش گونه های کاتیونی بین سطح و محتوای آب
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
چکیده انگلیسی


- Crystalline swelling behavior of montmorillonites has been modelled.
- Increasing number of calcium ions induce stronger swelling.
- The hydration energy of the ions plays a role in swelling behavior.

Molecular dynamic simulations are employed to study the crystalline swelling behavior of montmorillonites (MMTs) with different interlayer Na+ and Ca2+ ion compositions, and the effect of temperature and pressure on the swelling behavior. Non-linear increases in d-spacing are observed with increasing water content. Plateaus in the swelling curve for Na-MMT around d-spacings of 12 and 15 Å demonstrate the formation of 1- and 2-layer hydrate structures. Ca-MMT and mixed Na/Ca-MMTs exhibit similar swelling behavior with exception of showing stronger swelling at water contents corresponding to the 1-layer hydrate in Na-MMT. The stronger swelling in the calcium containing systems is attributed to the preference of Ca2+ to be fully coordinated to water molecules, which favors a 2-layer hydrate structure and increased d-spacings. The larger hydration energy of Ca2+ ions relative to Na+ ions promotes increased water coordination numbers and more pronounced association of water molecules with Ca2+ ions. The 1- and 2-layer hydrates for Na-MMT and the 2-layer hydrate for Ca-MMT were relatively stable to changes in temperature and pressure.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Physics - Volume 455, 9 July 2015, Pages 23-31
نویسندگان
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