کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10377820 | 880744 | 2005 | 19 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Morphology and surface properties of fumed silicas
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کلمات کلیدی
TSDCNonfreezable water1H NMR - 1H-NMRInterfacial water - آب درونیsurface charge density - تراکم سطحی سطحParticle size distribution - توزیع اندازه ذراتWater desorption - دفع آبSynthesis - سنتزfumed silica - سیلیس فومFTIR - طیف سنج مادون قرمزMorphology - مورفولوژی(ریخت شناسی)Zeta potential - پتانسیل زتا
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
شیمی کلوئیدی و سطحی
پیش نمایش صفحه اول مقاله

چکیده انگلیسی
Several series of fumed silicas and mixed fumed oxides produced and treated under different conditions were studied in gaseous and liquid media using nitrogen and water adsorption-desorption, mass spectrometry, FTIR, NMR, thermally stimulated depolarization current (TSDC), photon correlation spectroscopy (PCS), zeta potential, potentiometric titration, and Auger electron spectroscopy methods. Aggregation of primary particles and adsorption capacity (Vp) decrease and hysteresis loops of nitrogen adsorption-desorption isotherms becomes shorter with decreasing specific surface area (SBET). However, the shape of nitrogen adsorption-desorption isotherms can be assigned to the same type independent of SBET value. The main maximum of pore size distribution (gaps between primary nonporous particles in aggregates and agglomerates) shifts toward larger pore size and its intensity decreases with decreasing SBET value. The water adsorption increases with increasing SBET value; however, the opposite effect is observed for the content of surface hydroxyls (in mmol/m2). Associative desorption of water (2(SiOH) â SiOSi + H2O) depends on both the morphology and synthesis conditions of fumed silica. The silica dissolution rate increases with increasing SBET and pH values. However, surface charge density and the modulus of zeta-potential increase with decreasing SBET value. The PCS, 1H NMR, and TSDC spectra demonstrate rearrangement of the fumed silica dispersion depending on the SBET value and the silica concentration (CSiO2) in the aqueous suspensions. A specific state of the dispersion is observed at the CSiO2 values corresponding to the bulk density of the initial silica powder.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Colloid and Interface Science - Volume 289, Issue 2, 15 September 2005, Pages 427-445
Journal: Journal of Colloid and Interface Science - Volume 289, Issue 2, 15 September 2005, Pages 427-445
نویسندگان
V.M. Gun'ko, I.F. Mironyuk, V.I. Zarko, E.F. Voronin, V.V. Turov, E.M. Pakhlov, E.V. Goncharuk, Y.M. Nychiporuk, N.N. Vlasova, P.P. Gorbik, O.A. Mishchuk, A.A. Chuiko, T.V. Kulik, B.B. Palyanytsya, S.V. Pakhovchishin, J. Skubiszewska-ZiÄba, W. Janusz,