Application to Adsorption

Identification of the acid sites (especially the Brpnsted acid sites) on supports such as Vycor glass, zeolites, silica, and alumina is important in 

In the cases of the aluminosilicate and HY zeolite, the phosphorescence spectra represent a superposition of two different spectra. To separate them, each sample was excited in the region of least excitation spectra overlap. Thus, for the phosphorescence with a A ax of approximately 490 

The phosphorescence spectra of benzophenone dissolved in CCU and adsorbed on MgO, 7-AI2O3, and Si02 (all of which have a similar phosphorescence character) include four separable maxima (Table V) (216). The presence of these maxima, which are attributed to the electronic transitions from the excited state to lower vibrational levels of the ground electronic 

Peak Positions (A ) of the Phosphorescence Spectra of Benzopheneone (BP) under 

State of benzophenone (217), makes it possible to determine the positions of these vibrational levels. A significant decrease in all frequencies of the valence vibration and the overtones (Avq, Av2) of the carbonyl group in the adsorbed benzophenone can be observed when the spectrum is compared with the solution spectrum. Furthermore, as shown in Table V and Fig. 48, there is a good coincidence of the phosphorescence spectra of the solution and of the gaseous benzophenone (216-218), suggesting that there is no interaction between the benzophenone molecules. 

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Thomson s original equation is not suitable for direct application to adsorption data the form used by later workers, the Kelvin equation , is... 

Roginskif suggested a simplified method of analysis for processes occurring on a nonuniform surface which made it possible to surmount these mathematical difficulties without excessive distortion of the physical model. The method has general applicability to statistical processes however, its application to adsorption equilibrium only will be discussed here. 

It is widely accepted that localized adsorption is a result of large variation in potential energy from point to point on the adsorbent surface, and that the lateral interaction in such systems must be affected to some extent by the existence of these variations (3). This paper consists in a more quantitative formulation of these concepts than has been available previously. Furthermore, it is shown that, for adsorption on crystallographically perfect surfaces, a considerable amount of information about the nature of the potential field at the surface of the solid can be obtained from a proper treatment of the experimental data. This approach to the adsorption problem can also be extended to give the formal equations applicable to adsorption on a heterogeneous surface however, it seems unlikely that much practical use could be made of these equations because of the very large number of unknown parameters which appear. 

In his 1916 paper, Langmuir had stated that with highly porous adsorbents such as charcoal it is impossible to know definitely the area on which the adsorption takes place and that there are some spaces in which a molecule would be closely surrounded by carbon atoms on nearly all sides . He concluded that equations derived for plane surfaces were not applicable to adsorption by charcoal. Unfortunately, these observations have been overlooked by many investigators, who have applied the simple Langmuir monolayer equation to adsorption data obtained with zeolites and activated carbons. 

Having presented briefly the woiking procedures of the various methods, we now would like to illustrate their applications to adsorption of super and sub-critical fluids on non-porous carbon surface and in porous carbonaceous solids having slit pores. But first it is worthwhile to compare the time scales of computation of these methods ... 

In this review, the basic principles and practical aspects of photol uminescence techniques and their application to adsorption, catalysis, and photocatalysis phenomena have been summarized. We did not discuss studies on adsorption luminescence and/or chemiluminescence in which photons emitted by adsorption or chemical reactions are used to monitor adsorption and/or catalytic reactions on surfaces (255, 256). 

Ramirez-Pastor, A.J., Pereyra, V.D., and Riccardo, J.L. (1999). Statistical thermodynamics of linear adsorbates in low dimensions application to adsorption on heterogeneous surfaces. Langmuir, 15, 5707—12. 

If this equation is converted to a form applicable to adsorption from solution as was done for the Langmuir equation (equation 10.30), the result is... 

Macro-Kinetic Aspects of Langmuir s Theory and Its Application to Adsorption Dynamics... 

In order to illustrate why the sinusoidal input or frequency response technique is the most applicable in a gas-catalyst system with wide distributions in adsorption rates, a review of the tools of process dynamics and their application to adsorption studies is in order. 

Application to adsorption equilibria (A-28) and perfect gas (A-27) equation yields for n = PVjRT,... 

In this thermodynamic formulation, there is no mention of the nature of the chemical bonds and the status of the species involved. Therefore, this thermodynamic derivation is applicable to adsorption as well. As a matter of fact, it is applicable to any process in which something is converted into something else. 

In contrast to investigations of adsorption from the gas phase, the number of methods applicable to adsorption from the liquid phase is very small. On the one hand this is caused by the fact that not all methods using either electrons or ions can be applied in situ. In addition the adsorbents are normally powders with no plane surfaces. As a consequence the results of quantitative adsorption measurements are usually calculated from the difference between the liquid concentrations before and after the adsorption process. In principle, any analytical method may be used provided it has sufficient sensitivity pH measurements with a glass electrode and atomic adsorption spectroscopy (AAS) are standard, but complexometry and ion-selective electrodes can also be used. Radiochemical methods are useful in the case of small final concentrations. If electrochemical methods are used, one has to consider that activities, not concentrations, are obtained. In the case of partially soluble adsorbents, such as transition aluminas, their concentration should also be determined, as well as those of all other constituents of the solution, e.g., CO3. ... 

A separate approach used in predicting solute retention is the use of polarity parameters, P [53]. The F values for a wide range of solvents appear in Table 2.1. Unlike e°, P values are derived from partition equilibrium values and, therefore, have little direct application to adsorption-driven separations. Rather, P values are effectively used in separations involving reversed phases (e.g., octadecyl, octyl, and phenyl). For these systems, the partitioning equilibrium is the major retention process. 

Wang, M.L. Liou, C.T., and Chang, R.Y., Numerical technique for solving partial differential equations with applications to adsorption process, Comput. Chem. Eng., 4(2), 85-92 (1980). 

In a second paper Kazakevich and Eltekov consider the problem in terms of a layer of finite thickness, a treatment equally applicable to adsorption by microporous bodies where the adsorption volume is constant. They define a new system of activity coefficients (U and for both bulk and adsorbed phases write... 

Lu Y-M, Gong Q-M, Liang J (2009) Preparation of carbon nanotubes/activated carbon composite microspheres and their application to adsorption of VB12. Acta Phys Chim Sin 25(8) 1697-17202... 

Islam, M. M. Alam, M. T. Okajima, T. Oshaka, T. (2009). Electrical double layer structure in ionic liquids an understanding of the xmusual capacitance-potential curve at a nonmetallic electrode. /. Phys. Chem. C, Vol. 113,3386-3389 Johnson, M. Nordholm, S. (1981). Generalized van der Waals theory. VI. Application to adsorption. /. Chem. Phys., Vbl. 75,1953-1957... 

MC simulation Values for the chemical potential application to adsorption [225] Knight and Monson, 1986... 

S. Lantenois, B. Prdlot, J.-M. Douillard, K. Szczodrowski, M.-C. Charbonnel, Flow microcalorimetry experimental development and application to adsorption of heavy metal cations on silica. Appl. Surface Sci. 253(13), 5807-5813 (2007). doi 10.1016/j.apsusc.2006. 12.064... 

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