Some Applications Involving Solid-Liquid Interfaces

Some Applications Involving Solid-Liquid Interfaces... 

The adsorption from solutions at interfaces between two liquids and at solid-liquid interfaces is of importance in various applications. Many aspects of use of adsorption layers for monitoring the properties of disperse systems will be addressed in the subsequent chapters here we will just briefly list some typical examples of practical applications that involve adsorption from solutions on solid adsorbents. 

While there have been some successes in this area, however, BVT principles must be applied carefully to these systems. Bond-valence parameters are calibrated on precisely known structures of crystalline solids, for instance, so the application of the BVT to liquids and solid-liquid interfaces, for which less precise structural information is available, may not be straightforward. Furthermore, BVT-based reactivity models usually involve an implicit assumption that, at least for the purpose of predicting particular types of reaction energies, bond lengths are the dominant aspect of the stmcture. This may, or may not, be the case, depending on the reactions of interest. 

The book presents some basic considerations regarding liquid surfaces. After an introduction, the liquid-solid interface phenomena is described. Following this, the colloid chemistry systems are discussed, followed by emulsion science and technology. In the last chapter, more complex application examples are described. These are examples where different concepts of surface and colloid chemistry are involved in some mixed manner. 

The following five chapters deal with problems associated with solid phases, in some cases involving surface and interfacial problems. In Chapter 14, Steele presents a review of physical adsorption investigated by MD techniques. Jiang and Belak describe in Chapter 15 the simulated behavior of thin films confined between walls under the effect of shear. Chapter 16 contains a review by Benjamin of the MD equilibrium and non-equilibrium simulations applied to the study of chemical reactions at interfaces. Chapter 17 by Alper and Politzer presents simulations of solid copper, and methodological differences of these simulations compared to those in the liquid phase are presented. In Chapter 18 Gelten, van Santen, and Jansen discuss the application of a dynamic Monte Carlo method for the treatment of chemical reactions on surfaces with emphasis on catalysis problems. Khakhar in... 

Electrochemical reactions involve the transfer of electrons between an electronically conducting phase and localised energy levels on molecules or ions in an adjacent phase. In many cases, the reacting chemical species are present in an electrolyte solution, but interfacial charge transfer reactions can also involve solid ionic or covalent phases as well as ionic liquids (molten salts). Since the description of electron transfer should be applicable to a wide range of systems, it is useful to list some of the materials which can form part of the interface... 

This chapter and the two that follow are introduced at this time to illustrate some of the many extensive areas in which there are important applications of surface chemistry. Friction and lubrication as topics properly deserve mention in a textbook on surface chemistiy, partly because these subjects do involve surfaces directly and partly because many aspects of lubrication depend on the properties of surface films. The subject of adhesion is treated briefly in this chapter mainly because it, too, depends greatly on the behavior of surface films at a solid interface and also because friction and adhesion have some interrelations. Studies of the interaction between two solid surfaces, with or without an intervening liquid phase, have been stimulated in recent years by the development of equipment capable of the direct measurement of the forces between macroscopic bodies. 

This interface is critically important in many applications, as well as in biological systems. For example, the movement of pollutants tln-ough the enviromnent involves a series of chemical reactions of aqueous groundwater solutions with mineral surfaces. Although the liquid-solid interface has been studied for many years, it is only recently that the tools have been developed for interrogating this interface at the atomic level. This interface is particularly complex, as the interactions of ions dissolved in solution with a surface are affected not only by the surface structure, but also by the solution chemistry and by the effects of the electrical double layer [31]. It has been found, for example, that some surface reconstructions present in UHV persist under solution, while others do not. 

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