Page 7 - Adsorption by Powders and Porous Solids

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Ylll CONTEhT

Chapter 5. Adsorption at the Liquid-Solid Interface: Thermodynamics and
Methodology 117
5.1. Introduction 11 8
5.2. Energetics of immersion of solid in pure liquid 119
5.2.1. Thermodynamic background 119
Definition of immersion quantities 119
Relation between the energies of immersion and gas adsorption 121
Relation between the energies of immersion and adhesion 121
Relation between the areal surface excess energy and the surface
tension 124
Various types of wetting 125
Wettability of a solid suflace: definition and assessment 126
5.2.2. Experimental techniques of immersion microcalorimetry in pure
liquid 129
Recommended immersion microcalorimetric equipment and experimental
procedure 129
Evaluation of the correction terms 131
Critical aspects of immersion microcalorimetric techniques 131
5.2.3. Applications of immersion microcalorimetry in pure liquid 135
Evaluation of the wettability 135
Determination of the polarity of solid surfaces 135
Study of suflace modification 137
Assessment of the site-energy distribution 138
Assessment of structural modifications of the adsorbent 139
Assessment of microporosity 139
Assessment of sulface area 139
Further comments on the application of immersion microcalorimetry 140
5.3. Adsorption from liquid solution 140
5.3.1. Quantitative expression of the amounts adsorbed f?om a binary
solution 142
Scope and limitation of the normal suface excess amounts 142
The use of relative surface excess amounts 143
The use of reduced surface excess amounts 144
The meaning of relative and reduced suface excess amounts 145
Adsorption isotherms expressed in reduced surface excess amounts 146
5.3.2. Quantitative expressions of the energies involved in adsorption f?om
solution 148
Definitions of energies or enthalpies of adsorption from solution 148
Dqtinition of displacement enthalpies (and energies) 149
Definition of the enthalpies (and energies) of mixing 149
5.3.3. Basic experimental methods for the study of adsorption from
sollction 150
Methods for determining the amounts adsorbed 150
Methods for determining adsorption energies 153