کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
230285 1427371 2015 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Highly porous silica xerogels without surface modification
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Highly porous silica xerogels without surface modification
چکیده انگلیسی


• Silica xerogels with porosities up to 93% are observed.
• Neither surface modification nor forced ageing of the wet gels was applied.
• Oscillations in SAXS show a narrow particle size distribution.
• Low density correlates with predominant macroporous xerogels.

Silica xerogels with porosities up to 93% were prepared by a two-step process using tetraethoxysilane as silica source and a low water concentration in the stock solution. In the second step highly concentrated ammonia solutions were added (>0.5 mol/l). With these synthesis parameters, silica xerogels with densities down to 0.15 g/cm3 were prepared via ambient pressure drying at 50 °C. Depending on the synthesis parameters, the xerogels are either meso- or macroporous. Upon sample synthesis neither surface modification nor forced ageing of the wet gels was applied. Small angle X-ray scattering reveals oscillations in the Porod range of the scattering curves, indicating a narrow backbone particle size distribution. Differences between particle sizes determined via the two-phase model and the evaluation of the Porod-range can be explained by microporosity within the silica particles.

Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: The Journal of Supercritical Fluids - Volume 106, November–December 2015, Pages 160–166
نویسندگان
, ,