Determination of specific surface areas

Uses of adsorption studies Determination of catalytically active surface area and elucidation of reaction kinetics Determination of specific surface areas and pore size distributions... 

The determination of specific surface area using gas chromatographic equipment was first demonstrated by Nelson and Eggertsen (N/E) (2). In the N/E method, a quantity of sample is... 

Certain precautions are necessary in the determination of specific surface area, such as obtaining a representative sample, choosing the appropriate technique, and selecting standard materials for specific surface area analysis. The analyst should choose the technique and conditions of analysis that most closely approximate the intended use of the sample. Furthermore, precision studies should be carried out to see how sample handling affects the surface area. 

Nitrogen adsorption/condensation is used for the determination of specific surface areas (relative pressure < 0.3) and pore size distributions in the pore size range of 1 to 100 nm (relative pressure > 0.3). As with mercury porosimetry, surface area and PSD information are obtained from the same instrument. Typically, the desorption branch of the isotherm is used (which corresponds to the porosimetry intrusion curve). However, if the isotherm does not plateau at high relative pressure, the calculated PSD will be in error. For PSD s, nitrogen condensation suffers from many of the same disadvantages as porosimetry such as network/percolation effects and pore shape effects. In addition, adsorption/condensation analysis can be quite time consuming with analysis times greater than 1 day for PSD s with reasonable resolution. 

The determination of (specific) surface areas from Isotherms of this kind is usually a matter of empiricism because generally the constants cannot be... 

Determination of specific surface areas by adsorption from solution is a recurrent issue. Generally speaking there are two prerequisites ... 

Applications. Determination of specific surface area of filler which is used as a factor relative to particle size, porosity, and surface activity of filler. 

Sears, G.W., Determination of specific surface area of colloidal sihca by titration with sodium hydroxide. An /. Chem., 28, 1981. 1956. 

R. K. Schofield, Calculation of surface areas from measurements of negative adsorption, Nature 160 408 (1947). R. K. Schofield and O. Talibudeen, Measurement of the internal surface by negative adsorption. Disc. Faraday Soc. 3 51 (1948). H. J. van den Hul and J. Lyklema, Determination of specific surface areas of dispersed materials by negative adsorption, J. Colloid Interface Sci. 23 500 (1967). 

Uses of adsorption Determination of catalytically active Determination of specific surface areas... 

CoUins, K.E., Dimiras, A.B., de Camargo, V.R., and CoUins, C.H. 2006. Use of kinetic H20-adsorption isotherms for the determination of specific surface areas of fully hydroxylated mesoporous sUicas. Micropor. Mesopor. Mater. 89 246-250. 

Moller N, Seth PL, Setnikar I, Thoma K, Traisnel M (1986) Determination of specific surface area by gas pmneability. Comments to the monograph adopted by the Eirtopean Pharmacopoeia Cotrunis-siotL Pharm btd 48 775-9... 

The determination of specific surface area of soils and soil coUoids is of great importance in characterizing the reactivity of a sample, among other factors. However, it is actually an operational concept, because the A5 value depends on the experimental method employed, as it will be shown in Section 7.6.4.I. The underlying fact is that the effective area available for a particular reaction or process is dependent on the reactants and/or external factors involved. The experimental methods can be broadly classified into three categories (Sposito 1984) physical methods, positive adsorption methods, and negative adsorption methods. 

F. J. Micale, Deterinination of Vm and Effective Cross-Sectional Areas of Ar, N Kr for Determination of Specific Surface Areas, 49th Colloid Symposium, Clarkson College of Technology, Potsdam, N.Y.,June 14-16,1975. 

Determination of specific surface area by BET gas adsorption method... 

Another flow calorimetric approach to the determination of specific surface area is based on the preferential adsorption of CO2 from He, which is used as a carrier gas. Carbon dioxide produces close packed monolayers on most solids at room... 

Gas chromatographic determination of specific surface area has several advantages over the traditional BET adsorption method. It is more accurate when the... 

FIGURE 12.1 Schematic detector response in the N/E determination of specific surface area. 

BS 4359 Pt 2 (1982) Determination of Specific Surface Area of Powder. Permeametry the Kozeny-Carman Equation. BSI, Gunnersbury, London, UK. 

ASTM D4567. Standard Test Method for Single-Point Determination of Specific Surface Area of Catalysts and Catalyst Carriers Using Nitrogen Adsorption by Continuous Flow Method. ASTM Book of Standards Volume 05.05. Pennsylvania ASTM International ASTM D5604. Standard Test Methods for Precipitated Silica-Surface Area by Single Point B.E.T. 

The determination of specific surface area using small angle X ray scattering experiments in the Porod region leads to the same conclusion. This technique allows to explore the entire interface between solid and pore. The 5sp difference between the two techniques is attributed to the surface area lost in nitrogen adsorption measurement (Fig. 5-12). 

BS 4359 Methods for the Determination of Specific Surface Area of Powders. 

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