Role of Adsorption

1 This state of affairs has been immortalized in a song giving full coverage to the role of adsorption in eiectroorganic chemistry (Fleischmann etal., 1971b). 

As a rule anions and cations will tend to be adsorbed more strongly at respectively, positively and negatively charged surfaces, unless specific adsorption (p. 23) occurs. The maximum in the adsorption of organic compounds near or at the pzc has been verified 

Potentials of Zero Charge of Different Electrode Materials 

Electrode material Pzc, V versus see Electrode material Pzc, V versus see 

The 7r-bonding hypothesis is further supported by calculations of the differences in intrinsic free energy of adsorption, i.e., AGacjs, with the effect of displaced water molecules subtracted. For a series of butyl, phenyl and naphthyl derivatives these were found to be —6-4, —8-9, and —12 4 kcal mole-1, respectively. 

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Process Concepts. Hybrid systems involving gas-phase adsorption coupled with catalytic processes and with other separations processes (especially distillation and membrane systems) will be developed to take advantage of the unique features of each. The roles of adsorption systems will be to efficiently achieve very high degrees of purification to lower fouUng contaminant concentrations to very low levels in front of membrane and other separations processes or to provide unique separations of azeotropes, close-boiling isomers, and temperature-sensitive or reactive compounds. 

In tills chapter we consider systems in which a reaction between two gaseous species is carried out in die adsorbed state on die surface of a solid. The products of die reaction will be gaseous, and die solid acts to increase die rate of a reaction which, in die gaseous state only, would be considerably slower, but would normally yield die same products. This effect is known as catalysis and is typified in industty by die role of adsorption in increasing die rate of syndiesis of many organic products, and in die reduction of pollution by die catalytic converter for automobile exliaust. 

A specific role of adsorption potentials U j,angular dependences, they also... 

Hering, J.G., P.Y. Chen, and J.A. Wilkie. 1997. Arsenic removal from drinking-water by coagulation the role of adsorption and effects of source water composition. Pages 369-381 in C.O. Abernathy, R.L. Calderon, and W.R. Chappell (eds.). Arsenic. Exposure and Health Effects. Chapman Hall, London. 

The relative importance of the EDL for reactions other than adsorption is not well understood. Surface complexation models have recently been applied to processes in which adsorption represents the first step in a sequence of reactions. For example, Stumm et al. (22) have applied a model with an EDL component in their studies of the role of adsorption in dissolution and precipitation reactions. The effect of surface charge and potential on precipitation and the... 

Role of adsorption in photocatalyzed reactions of organic molecules in aqueous titania suspensions, Langmuir 8 (1992) 481. 

Pr = It couples the role of adsorption strength together with the diffusion mass transport on the time scale of potential pulses. If the adsorption is very weak, Pr > 1.23, the response of reaction (2.144) is equivalent to the simple reaction of a dissolved redox couple (2.157). 

Current interest in the multi-faceted role of adsorption in the water and waste water field has been stimulated in large part by research originating within this field. Concomitantly, more and more investigations in the field of surface and colloid chemistry have focused on aqueous systems. The results of these investigations are of considerable significance to the water scientist. The convergence of interests of researchers in these two fields has provided the impetus for this joint symposium on adsorption from aqueous solution. 

The Role of Adsorption of Hydrolyzed Aluminum in the Kinetics of Coagulation... 

The Role of Adsorption in the Destabilization of Colloidal Dispersions by Hydrolyzed Al(III)... 

The olefinic group of vinylpyridines undergoes a variety of reactions, which include reduction to the ethane, addition reactions, dimerizations, and polymerizations. There are few voltammetry studies on the isomeric vinylpyridines (26). The reduction of the bisquaternary salt of 1,2-di(2-pyridyl)-ethylene has been studied, and the role of adsorption and autoinhibition during reduction of l,2-di(4-pyridyl)ethylene was also determined.49,50... 

Fanale, F. P., Cannon, W. A. (1972) Origin of planetary rare gas The possible role of adsorption. Geochim. Cosmochim. Acta, 36, 319-28. 

A possible cause for the suppression of a low-potential process in favor of a high-potential one is considered to be preferential adsorption 2l 63> of the substrate of the high-potential process on the electrode surface. The electrode then becomes blocked for the other process. The role of adsorption for the synthetic outcome of an organic electrode process is difficult to ascertain at the present state of our knowledge but might well be very important. In the following, we shall have occasion to discuss several reactions in which products of an unusual nature are found and where adsorption might be the cause of their formation. 

If we also consider the role of adsorption on the distribution of products, then we should note that surface concentrations of substrate and intermediate(s) must be taken into account, i.e. their concentrations in the inner Helmholtz layer (cf. for example, Wendt, 1973). One effect of this would possibly be to... 

The first mechanistic problem of importance is to find out the nature of the electroactive species for the electrode reaction of interest. Once this has been established, the way is open for mechanistic studies of a higher order, such as the reaction sequence, the role of adsorption, reactivity, and so on. 

Minero, C., Catozzo, F., and Pelizzetti, E., Role of adsorption in photocatalyzed reactions of organic molecules in aqueous TiOa suspensions . Langmuir. 8, 481 (1992). 

ON THE DOMINANT ROLE OF ADSORPTION EFFECTS IN HETEROGENEOUS CATALYSIS... 

Banks WA, Kastin AJ, Akerstrom V (1997) HIV-1 protein gpl20 crosses the blood-brain barrier Role of adsorptive endocytosis. LifeSci61 L119-L125. 

Contemporary issues and developments relating to the application of activated carbon adsorption processes for water and wastewater treatment are discussed. Consideration is given to the increasingly important role of adsorption as a technology for removing specific target compounds or classes of compounds from waters and wastewaters... 

The passage of electric current through a nonmetallic liquid is dependent on ions. The choice of electrolyte depends on such properties as its solubility, dissociation constant, mobility, discharge potential, and protic activity. It is desirable to employ a salt with high solubility, complete dissociation, high mobility of the ions, and a numerically high discharge potential. The role of adsorption of ions at the electrode is discussed elsewhere. The electrolyte may influence the rate constant for electron transfer from an electrode to a substrate. 

The role of adsorption in electrocatalysis is as important as it is in heterogeneous catalysis. In aqueous electrochemistry, the... 

Orientation Effects Induced by the Electrode Surface Competing Reactions the Role of Adsorption Adsorption versus -values. ... 

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