Surface specific area

Characterization. When siHca gel is used as an adsorbent, the pore stmcture determines the gel adsorption capacity. Pores are characterized by specific surface area, specific pore volume (total volume of pores per gram of solid), average pore diameter, pore size distribution, and the degree to which entrance to larger pores is restricted by smaller pores. These parameters are derived from measuring vapor adsorption isotherms, mercury intmsion, low angle x-ray scattering, electron microscopy, gas permeabiHty, ion or molecule exclusion, or the volume of imbibed Hquid (1). 

Mean particle size Surface area Specific pore volume Dispersion (pm) (m /g) (ml/g) (%)... 

Catalyst Rate (nmol h g- ) Surface area ( Specific Activity (nmol h m )... 

Catalyst Acidity bv Ammonia Chemisorption. Plant performances below expectations were reported by two units, in which the original alumina based catalysts were replaced. Surface area specifications were 150-200 m2/g for both catalysts. Acidity was measured by ammonia chemisorption using a recording vacuum thermoanalyzer with a TGA sample holder, and was correlated with BET surface area, as shown in Table V. 

To evaluate the basic characteristics of de-SOx over ACF, comparison was made between 4 kinds of commercialized ACFs under the untreated condition. Table 1 shows the comparison of the properties of ACFs. Because the structures such as an external surface area, specific surface area, and pore size are unified in the manufacturing process, there is slight difference in structure of raw materials. But the compositions of raw materials significantly vary with types phenol-type (Kuraray Chemicals co.,ltd.) or... 

Engelhardt and Mliller reported on the differences in the physical properties, such as specific surface area, specific pore volume and average pore diameter - and on the different amounts of stationary and mobile phase per unit column volume for various commercially available silica gels. If the retention for various solutes were normalized for these factors, distinct selectivities were still noticed. This could be explained by differences in the surface pH of the silicas. Irregular ones were usually neutral or weakly acidic, whereas the spherical ones were either acidic (pH ca.4) or basic (pH ca.9) (see Table 1.4).To obtain the required and optimum selectivity, the pH of silica gel can easily be adjusted. For basic compounds more symmetrical peak shapes were obtained on silica with a basic character. 

The C-Fe-pp model exhibited Cation Exchange Capacity, Specific Surface Area, Specific Cationic Surface Charge, Titratable Acidity, and P sorption capacity higher than C-Al-pp. For both model, the amounts of P desorbable by EUF were much lower than the amounts of P initially added. However, the C-Fe-pp model was less able than C-Al-pp in retaining the initially added P. Evidently, distinct mechanisms controlled the interactions of P with C-Al-pp or C-Fe-pp in both sorption and desorption phenomena. In particular, the presence of Al- or... 

Surface Area Specific Mean Pore Solubility... 

In order to obtain true surface area specific rate constants for the surface kinetics, the real (microscopic) surface area must be taken into account. For powders, the Brunauer, Emmett, Teller (BET) method may be used to determine the true surface area. Eor dense solid bodies, however, the BET method may be too insensitive, since the overall surface area is relatively low. In such cases, measurements of the surface roughness, for example by atomic force microscopy (AFM),... 

The isoterms of adsorption of maleimide-activated immunoglobulins on the surface of Fe304/DMSA were investigated. The adsorption capacity value was A=92.12mg/g (Table 10.7), with the specific surface area specific = 130 m /g. The release of immunoglobulin, immobilized by means of sulfo-SMCC spacer, in the model medium was 8—12% for 24 h. 

The unique property of nanoparticles that is most widely utilized in the applications of rare earth oxides and sulphides is their high specific surface area. Specific surface area is defined as the surface area per unit weight. As the particle size is reduced, more atoms are exposed on the particle surface and hence the specific surface area increases drastically (Table 2). For example, when the particle diameter is reduced to 1 nm, only 1 g of Ce02 nanoparticles can have a surface area of 800 m, three times larger than the official tennis court. On the other hand, if the particles have a diameter of 100 pm, then 1 g of the powder has only 0.008 m of surface... 

In straight phase chromatography, it is the hydroxyl groups on the surface of the silica which are the polar, active centers where most of the interactions take place in the retention of the compounds to be separated. These interactions are mainly hydrogen-bonding and induced dipole-dipole. Generally, the phase can be characterized with the following three characteristic values specific surface area, specific pore volume, mean pore diameter. 

Figure I.6a displays a selection of fuel cell polarization curves extracted from publications that span a period of 125 years. The ordinate depicts the fuel cell voltage Eceii (jo) as given in Equation 1.21. The abscissa represents, on a logarithmic scale (to the base of 10), the fuel cell current density that has been normalized to the surface area-specific mass loading of Pt, mpf.

---