Adsorption and the Gibbs surface excess

BOOK REVIEWS Adsorption and the Gibbs Surface Excess. By D. K. CHATTORAJAND K. S. BIRDI. Plenum, New York, 1984. 471 pp., $59.50. The adsorption of low- and high-molecular-weight substances, solvent, electrolytes, tensides, etc. from solution is of considerable importance in surface and colloid science, physical biochemistry, and biology and becomes of increasing interest in many areas of applied sciences (i.e., stabilization of emulsions, suspensions and aerosols; wetting; adhesion; membranes). Research in these areas of science and technology has increased substantially in recent years. In this book the authors attempt to describe the adsorption phenomena at solid-liquid, liquid-liquid, and liquid-gas interfaces from multicomponent solutions with equations deduced from the unified concept of Gibbs surface excess. Investigators, students, and beginners will be introduced to the basic idea, the derivation of the Gibbs equations and their application. After a very compact presentation of the thermodynamic quantities of the bulk phase and of the interface (Chap. 1) the methods and techniques of measuring boundary properties are described (Chap. 2). The original derivation of the Gibbs equation assuming a two-dimensional surface is presented in a clear way, recognizing the difficulties of the surface concept in relation to the three-dimensional interracial phase. Fundamental relations between the surface excess quantities and the composition of the bulk phase and of the actual interracial phase are derived following a special approach. The chemical potentials, the activity coefficients, and the surface excess entropy of the surface phase are deduced (Chap. 3). Suitable adsorption equations for multicomponent electrolytic aqueous solutions are proposed on the basis of electric double-layer models given by Helmholtz, Gouy, and Stern (Chap. 4). Equations of state based on different theoretical models

for the interfacial double layers (Chap. 5) and properties of spread monolayers (Chap. 6) are discussed. Interfacial systems of gas-solid-liquid and liquid-solid-liquid are reported with respect to wettability and contact angles (Chap. 7). Special chapters are related to the adsorption of nonionic, ionic, and especially polymeric substances at solidliquid interfaces (Chap. 8) and to the adsorption of water by biopolymers (Chap. 9) in the presence of electrolytes and nonelectrolytes. Excess binding and standard free enthalpies of binding of solute and solvent to biopolymers are treated (Chap. 10). Miscellaneous systems and problems such as micelle formation, hydration of powdered detergents, adsorption of inorganic electrolytes and gases at solid-water interfaces, size and stability of microemulsions, and kinetic aspects of the adsorption process are summarized in Chapter 11. In all chapters the theoretical values and trends are compared with experimental results. Citing fundamental books and articles repeatedly in different chapters the literature list becomes unnecessarily long. In some chapters the latest literature is not considered in the discussion, i.e., papers on polymer adsorption are only cited up to 1973, though essential progress has been achieved in the last few years. Some references to equations and figures are not correct and some misleading printing errors exist. But an attentive and careful reader can easily eliminate these deficiencies. The clear condensed treatment of the subject of adsorption from solution in one volume based on the idea of Gibbs surface excess is an essential contribution to a better understanding of interfacial phenomena. This unique treatise from an unusual point of view can stimulate the experimental scientist in this field to interpret his results in a new way. E. KILLMANN

602 0021-9797/86 $3.00 Copyright © 1986 by Academic Press, Inc. All rights of reproduction in any form reserved.

Journal of Colloid and Interface Science, Vol. 112, No. 2, August 1986