کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9617602 | 49169 | 2005 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Kinetics of ion exchange in quasi-crystalline aluminosilicate zeolite precursors
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
کاتالیزور
پیش نمایش صفحه اول مقاله

چکیده انگلیسی
The kinetics of binary ion exchange of Ca2+ and Mg2+ for Na+ in quasi-crystalline and crystalline zeolite A has been investigated. Diffusion of either divalent cation into crystalline zeolite NaA is relatively fast, while the exchanges are slower in the quasi-crystalline precursor materials. The diffusion coefficient for Mg2+ exchange (D(Mg)) into crystalline zeolite A is an order of magnitude lower than that of Ca2+ (D(Ca)), due to the larger hydration sphere of the Mg2+ ion. However, the ratio (D(Ca):D(Mg)) was found to scale with the degree of crystallinity of the sample. Calcium and magnesium ions diffuse into the quasi-crystalline materials at comparable rates; this phenomenon is ascribed to the presence of larger pores in the quasi-crystalline structure, as compared to the crystalline material. Low impact mechanical treatment of quasi-crystalline zeolite precursors further decreases the difference between D(Ca) and D(Mg), while the crystallinity of the material is not noticeably decreased.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Microporous and Mesoporous Materials - Volume 84, Issues 1â3, 15 September 2005, Pages 171-178
Journal: Microporous and Mesoporous Materials - Volume 84, Issues 1â3, 15 September 2005, Pages 171-178
نویسندگان
Eric N. Coker, Lovat V.C. Rees,