Adsorption calculation

Tien, C., 1994, Adsorption Calculations and Modeling , Butterworth-Heinemann, Boston, USA. 

Tien, Chi Adsorption Calculations and Modeling (Butterworth, Boston, 1994). 

Very often thermodynamic parameters of adsorption, calculated from different isotherms and reported in the literature, can scarcely be compared because the standard-state conditions used in the calculation are not specified. 

The most important FeSa surface is the (100) surface, which is the most common growth surface and is also the perfect cleavage surface. Research from Nesbitt et al. (1998) suggest that the (100) surface of pyrite exhibits good stability and only minimal relaxation fi om the truncated solid. Therefore, our adsorption calculation is based on FeSa (100) surface and the relaxation of surface is ignored. 

When a surfactant is injected into the liquid beneath an insoluble monolayer, surfactant molecules may adsorb at the surface, penetrating between the monolayer molecules. However it is difficult to determine the extent of this penetration. In principle, equilibrium penetration is described by the Gibbs equation, but the practical application of this equation is complicated by the need to evaluate the dependence of the activity of monolayer substance on surface pressure. There have been several approaches to this problem. In this paper, previously published surface pressure-area Isotherms for cholesterol monolayers on solutions of hexadecy1-trimethyl-ammonium bromide have been analysed by three different methods and the results compared. For this system there is no significant difference between the adsorption calculated by the equation of Pethica and that from the procedure of Alexander and Barnes, but analysis by the method of Motomura, et al. gives results which differ considerably. These differences indicate that an independent experimental measurement of the adsorption should be capable of discriminating between the Motomura method and the other two. 

All three methods rely on the accurate determination of the slopes of curves. This is a major source of error when there is some scatter in the data, as there is in this case. However, it is not sufficient to explain the differences between the Motomura analyses on the one hand and the adsorptions calculated by the other two methods. 

Initial Heats of Adsorption Calculated from Bond Energies and Dipole Moments ... 

The maximum surface concentration of benzoic acid obtained by extrapolation of the experimental data is rmax = 5.1 X 1014 molecules cm-2. Determine the parameters P and A in the Frumkin equation of adsorption. Calculate the Gibbs energy of adsorption. Compare the results with the Langmuir isotherm. (Sobkowski)... 

Adsorption is a physical phenomenon in which some components adsorbates) in a fluid (liquid or gas) move to, and accumulate on, the surface of an appropriate solid adsorbent) that is in contact with the fluid. With the use of suitable adsorbents, desired components or contaminants in fluids can be separated. In bioprocesses, the adsorption of a component in a liquid is widely performed by using a variety of adsorbents, including porous charcoal, silica, polysaccharides, and synthetic resins. Such adsorbents of high adsorption capacities usually have very large surface areas per unit volume. The adsorbates in the fluids are adsorbed at the adsorbent surfaces due to van der Waals, electrostatic, biospecific, or other interactions, and thus become separated from the bulk of the fluid. In practice, adsorption can be performed either batchwise in mixing tanks, or continuously in fixed-bed or fluidized-bed adsorbers. In adsorption calculations, both equilibrium relationships and adsorption rates must be considered. 

The total accessible pore volume may be measured by the amount of adsorbate at the saturation pressure of the adsorptive, calculated as liquid volume, provided the adsorption on the external surface can be neglected or can be evaluated. The accessible pore volume may be different for molecules of different sizes. A method which is not subject to the effect of the external surface is the determination of the dead space by means of a non-sorbable gas (normally helium) in conjunction with the determination of the bulk volume of the adsorbent by means of a non-wetting liquid or by geometrical measurements. 

Finally Table 5 summarizes the most important global properties of the interacting systems. The charge transfer AQ is defined by the fraction of electrons transfered from the methane molecule to the host cluster on adsorption, calculated... 

The functions J>fe(x) have been tabulated for values of k up to 4. For higher values of k the function must be calculated by Equation 10 fortunately one can neglect all but the first term of the series for k>4, provided x<2, as is commonlv the case in adsorption calculations. 

The integral heat of adsorption is the difference between the heat of immersion of the clean adsorbent and the heat of immersion of the adsorbent, with n2 moles of X2 adsorbed upon it. This calorimetric heat of adsorption is to be compared with the heat of adsorption calculated from the temperature coefficient of the integral free energy change by Equation 6. 

Autoradiographs of GBH surfaces sometimes show a "strike where the aqueous solution of heparin was delivered by a pipette, and ran down the film, as seen in Figure 1, which shows the two sides of an adsorption sack with graphite-benzalkonium surface. The match of the adsorption pattern on the two surfaces indicates that it was a matter of initial contact with solution, not a property of the surfaces. This pattern was produced on an initially dry GB surface. The solution was 90% cold heparin, 10% tagged heparin, at 67 fig. tagged heparin/ml. The average heparin adsorption, calculated as total (10X radioactive heparin adsorption) from depletion of the solution, was 2.7 fig./cm.2 Sack was rotated 20 hours, with a bubble, at 37 °C. 

Equilibrium Observed Pb Particulate Particulate Pb Adsorption Calculated from Isotherms ... 

Schindler (29, 30) took whole-ocean residence times for various elements, as given by Goldberg (32), and found reasonable agreement between these and the residence times with respect to adsorption calculated from his model. His choice of properties took h equal to 10 , Tp for particulate silica to be 2 x 10 years and a to be 2 x 10 ° kg of suspended silica 1 (2 mg silica 1" ). The term Co was taken to be 1.0 mol kg of silica, which led to a value of C of 0.509 mol kg , indicating that approximately 50% of the surface silanol groups are occupied by adsorbed The choice of silica as a model oxide surface is... 

The same set of effective potentials is used in all subsequent calculations on the Ni(lll) surface and for all adsorption calculations. 

Isosteric heat G. J mol Heat of adsorption calculated from isotherms of adsorption G, = RTHd nP/dT) (Clapeyron)... 

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