کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6438008 | 1637997 | 2015 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Temperature dependence of interfacial structures and acidity of clay edge surfaces
ترجمه فارسی عنوان
وابستگی دما به ساختارهای موازی و اسیدیته سطوح لبه خاک رس
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
In the pursuit of a microscopic understanding of the effects of temperature on the surface reactivity of clay minerals, we conducted first principles molecular dynamics (FPMD) simulations to study the interfacial structures and acidity of clay edge surfaces at elevated temperatures. The common edge surfaces ((0Â 1Â 0) and (1Â 1Â 0) types) of phyllosilicates were investigated at 348Â K and 423Â K, and the results were compared with those previously derived at ambient conditions. We found that the stable surface sites are the same as at ambient conditions, including Al(OH2)2 (6-fold Al), Al(OH2) (5-fold Al) and Si(OH) on the (0Â 1Â 0) facet, and Al(OH2), Al(OH)Si and Si(OH) on the (1Â 1Â 0) surface. The FPMD-based vertical energy gap technique was applied to compute the acidity constants of edge sites and the resulting pKa values show a decreasing trend with temperature. The results demonstrate that although changes in the point of zero charge of the entire material are insignificant up to 348Â K, the decrease in surface pKa can be 3Â pKa units, while it can be as large as 6Â pKa units up to 423Â K. The derived interface structures and pKa values can be used in future experimental and modeling research, e.g., in interpreting experiments and predicting the surface complexation of metal cations and organics. This study therefore provides a physical basis for investigating the interfacial processes of clay minerals in environments that experience elevated P-T conditions, such as sedimentary basins and geological nuclear waste repositories.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geochimica et Cosmochimica Acta - Volume 160, 1 July 2015, Pages 91-99
Journal: Geochimica et Cosmochimica Acta - Volume 160, 1 July 2015, Pages 91-99
نویسندگان
Xiandong Liu, Xiancai Lu, Jun Cheng, Michiel Sprik, Rucheng Wang,