ABSTRACT

I. Introduction 358

II. Adsorption and Heat of Immersion on Solids in Pure Liquids and Binary Liquid Mixtures 359 A. Heat of immersion at solid/liquid interfaces 359 B. Adsorption of binary liquid mixtures on dispersed

solid particles 362 C. Combination of adsorption excess isotherms and

enthalpy isotherms: new way to determine adsorption capacity 365 D. Adsorption excess and enthalpy isotherms on solids

in binary liquids 367 E. Classification of enthalpy isotherms 375

III. Heat of Immersion on Hydrophilic and Hydrophobic Colloidal Particles in Different Liquid Mixtures 377 A. Heat of Wetting in amorphous silica dispersion and

on zeolites 377 B. Immersional wetting on nonswelling clay minerals 380 C. Heat of wetting on swelling clay minerals 386 D. Adsorption of n-butanol from water on modified

silicate surfaces 392

IV. Properties of the Adsorption Layer and Stability of Aerosil Dispersions in Binary Liquids 397 A. Influence of the adsorption layer on the aggregation of

aerosil dispersions in binary liquids 398 B. Characterization of the stability of nonaqueous dispersions

by calorimetric and adsorption measurements 401

V. Small-Angle X-Ray Scattering of SiO2 Particles in Binary Liquids 408

References 409

I. INTRODUCTION The stabilization of colloidal disperse systems in various liquids is primarily influenced by the difference between the polarities of the solid particles and the liquid. Thus, metal oxides may be dispersed in aqueous media to form stable hydrosols or in alcohols to produce stable alcosols [1]. Stable dispersions are also obtained in the same way in organic media if the polarity of the surface is altered, i.e., hydrophobized by long alkyl chains, resulting in the establishment of stable organosols or suspensions [2-6]. The determinative factor is the magnitude of the interparticle interaction potential, which can be calculated on the basis of Hamaker constants [7]. The equations describing interaction potential, thus allowing the calculation of interparticle interactions, were formulated by Vold [3] and Vincent [5]. Interparticle interactions and consequently the stability of disperse systems may also be adequately characterized by the properties of the sorption layer formed on the surface of solid particles.