Introduction to Applied Colloid and Surface Chemistry E-Book

Georgios M. Kontogeorgis

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 858

Veröffentlichungsjahr: 2016

Beschreibung

Colloid and Surface Chemistry is a subject of immense importance and implications both to our everyday life and numerous industrial sectors, ranging from coatings and materials to medicine and biotechnology.

How do detergents really clean? (Why can't we just use water?) Why is milk "milky"? Why do we use eggs so often for making sauces? Can we deliver drugs in better and controlled ways? Coating industries wish to manufacture improved coatings e.g. for providing corrosion resistance, which are also environmentally friendly i.e. less based on organic solvents and if possible exclusively on water. Food companies want to develop healthy, tasty but also long-lasting food products which appeal to the environmental authorities and the consumer. Detergent and enzyme companies are working to develop improved formulations which clean more persistent stains, at lower temperatures and amounts, to the benefit of both the environment and our pocket. Cosmetics is also big business! Creams, lotions and other personal care products are really just complex emulsions.

All of the above can be explained by the principles and methods of colloid and surface chemistry. A course on this topic is truly valuable to chemists, chemical engineers, biologists, material and food scientists and many more.

Leseprobe

Table of Contents

Cover

Title Page

Preface

References

Useful Constants

Symbols and Some Basic Abbreviations

About the Companion Web Site

1 Introduction to Colloid and Surface Chemistry

1.1 What are the colloids and interfaces? Why are they important? Why do we study them together?

1.2 Applications

1.3 Three ways of classifying the colloids

1.4 How to prepare colloid systems

1.5 Key properties of colloids

1.6 Concluding remarks

Appendix 1.1

Problems

References

2 Intermolecular and Interparticle Forces

2.1 Introduction – Why and which forces are of importance in colloid and surface chemistry?

2.2 Two important long-range forces between molecules

2.3 The van der Waals forces

2.4 Concluding remarks

Appendix 2.1 A note on the uniqueness of the water molecule and some of the recent debates on water structure and peculiar properties

References for the Appendix 2.1

Problems

References

3 Surface and Interfacial Tensions – Principles and Estimation Methods

3.1 Introduction

3.2 Concept of surface tension – applications

3.3 Interfacial tensions, work of adhesion and spreading

3.4 Measurement and estimation methods for surface tensions

3.5 Measurement and estimation methods for interfacial tensions

3.6 Summary

Appendix 3.1 Hansen solubility parameters (HSP) for selected solvents

Appendix 3.2 The “ϕ” parameter of the Girifalco–Good equation (Equation 3.16) for liquid–liquid interfaces. Data from Girifalco and Good (1957, 1960)

Problems

References

4 Fundamental Equations in Colloid and Surface Science

4.1 Introduction

4.2 The Young equation of contact angle

4.3 Young–Laplace equation for the pressure difference across a curved surface

4.4 Kelvin equation for the vapour pressure,

P

, of a droplet (curved surface) over the “ordinary” vapour pressure

P

sat

for a flat surface

4.5 The Gibbs adsorption equation

4.6 Applications of the Gibbs equation (adsorption, monolayers, molecular weight of proteins)

4.7 Monolayers

4.8 Conclusions

Appendix 4.1 Derivation of the Young–Laplace equation

Appendix 4.2 Derivation of the Kelvin equation

Appendix 4.3 Derivation of the Gibbs adsorption equation

Problems

References

5 Surfactants and Self-assembly. Detergents and Cleaning

5.1 Introduction to surfactants – basic properties, self-assembly and critical packing parameter (CPP)

5.2 Micelles and critical micelle concentration (CMC)

5.3 Micellization – theories and key parameters

5.4 Surfactants and cleaning (detergency)

5.5 Other applications of surfactants

5.6 Concluding remarks

Appendix 5.1 Useful relationships from geometry

Appendix 5.2 The Hydrophilic–Lipophilic Balance (HLB)

Problems

References

6 Wetting and Adhesion

6.1 Introduction

6.2 Wetting and adhesion via the Zisman plot and theories for interfacial tensions

6.3 Adhesion theories

6.4 Practical adhesion: forces, work of adhesion, problems and protection

6.5 Concluding remarks

Problems

References

7 Adsorption in Colloid and Surface Science – A Universal Concept

7.1 Introduction – universality of adsorption – overview

7.2 Adsorption theories, two-dimensional equations of state and surface tension–concentration trends: a clear relationship

7.3 Adsorption of gases on solids

7.4 Adsorption from solution

7.5 Adsorption of surfactants and polymers

7.6 Concluding remarks

Problems

References

8 Characterization Methods of Colloids – Part I

8.1 Introduction – importance of kinetic properties

8.2 Brownian motion

8.3 Sedimentation and creaming (Stokes and Einstein equations)

8.4 Kinetic properties via the ultracentrifuge

8.5 Osmosis and osmotic pressure

8.6 Rheology of colloidal dispersions

8.7 Concluding remarks

Problems

References

9 Characterization Methods of Colloids – Part II

9.1 Introduction

9.2 Optical microscopy

9.3 Electron microscopy

9.4 Atomic force microscopy

9.5 Light scattering

9.6 Spectroscopy

9.7 Concluding remarks

Problems

References

10 Colloid Stability – Part I

10.1 Introduction – key forces and potential energy plots – overview

10.2 van der Waals forces between particles and surfaces – basics

10.3 Estimation of effective Hamaker constants

10.4 vdW forces for different geometries – some examples

10.5 Electrostatic forces: the electric double layer and the origin of surface charge

10.6 Electrical forces: key parameters (Debye length and zeta potential)

10.7 Electrical forces

10.8 Schulze–Hardy rule and the critical coagulation concentration (CCC)

10.9 Concluding remarks on colloid stability, the vdW and electric forces

Appendix 10.1 A note on the terminology of colloid stability

Appendix 10.2 Gouy–Chapman theory of the diffuse electrical double-layer

Problems

References

11 Colloid Stability – Part II

11.1 DLVO theory – a rapid overview

11.2 DLVO theory – effect of various parameters

11.3 DLVO theory – experimental verification and applications

11.4 Kinetics of aggregation

11.5 Concluding remarks

Problems

References

12 Emulsions

12.1 Introduction

12.2 Applications and characterization of emulsions

12.3 Destabilization of emulsions

12.4 Emulsion stability

12.5 Quantitative representation of the steric stabilization

12.6 Emulsion design

12.7 PIT – Phase inversion temperature of emulsion based on non-ionic emulsifiers

12.8 Concluding remarks

Problems

References

13 Foams

13.1 Introduction

13.2 Applications of foams

13.3 Characterization of foams

13.4 Preparation of foams

13.5 Measurements of foam stability

13.6 Destabilization of foams

13.7 Stabilization of foams

13.8 How to avoid and destroy foams

13.9 Rheology of foams

13.10 Concluding remarks

Problems

References

14 Multicomponent Adsorption

14.1 Introduction

14.2 Langmuir theory for multicomponent adsorption

14.3 Thermodynamic (ideal and real) adsorbed solution theories (IAST and RAST)

14.4 Multicomponent potential theory of adsorption (MPTA)

14.5 Discussion. Comparison of models

14.6 Conclusions

Acknowledgments

Appendix 14.1 Proof of Equations 14.10a,b

Problems

References

15 Sixty Years with Theories for Interfacial Tension –

Quo Vadis

?

15.1 Introduction

15.2 Early theories

15.3 van Oss–Good and Neumann theories

15.4 A new theory for estimating interfacial tension using the partial solvation parameters (Panayiotou)

15.5 Conclusions –

Quo Vadis

?

Problems

References

16 Epilogue and Review Problems

Review Problems in Colloid and Surface Chemistry

Index

End User License Agreement

List of Tables

Chapter 01

Table 1.1

Examples of colloidal systems, i.e. one type of compound, e.g. solid particles or liquid droplets, in a medium. Different combinations are possible depending on the phase of the particles (dispersed phase) and the (dispersion) medium they are in. Two gas phases will mix on a molecular level and do not form a colloidal system.

Table A1

Overview of what can be measured and what can be calculated in the area of colloid and surface chemistry

Chapter 02

Table 2.1

Change in standard molar Gibbs energy, enthalpy and entropy (all in kJ mol

–1

) for the transfer of hydrocarbons from pure liquids into water at 25 °C (Prausnitz, Lichtenthaler and de Azevedo, 1999; Gill and Wadso, 1976). Notice the large negative entropy changes due to the hydrophobic effect. In the case of

n

-butane, the entropy decrease amounts to 85% of the Gibbs energy of solubilization, while for other hydrocarbons the entropic contribution is even larger

Table 2.2

Van der Waals interaction (potential) energies between particles/surfaces;

V

A

is the potential energy (in J or J m

–2

for the interaction between two surfaces),

H

is the interparticle/intersurface distance and

R

is the radius (for spherical particles);

A

is the Hamaker constant (see Equations 2.6–2.8 and Hamaker, 1937) and, depending on the application, is evaluated under conditions of either vacuum/air or a dielectric (i.e. a liquid medium, in which case an effective Hamaker constant must be used).

C

is defined in Equation 2.6 and

ρ

is the number density (molecules/volume)

Table 2.3

Comparison of intermolecular forces between two identical molecules. The

C

-values of the van der Waals forces (

) for identical molecules are given at 0 °C; C-values are expressed in 10

–79

J m

6

Table 2.4

Multiple choice questions

Table 2.5

Blend-solvent miscibility

Chapter 03

Table 3.1

Surface tension values for typical liquids and solids (in mN m

–1

)

.

The solid surface tension values are “ideal” (production under vacuum) and will be much lower under normal laboratory conditions or after exposure in air. Except otherwise indicated, the values are at 20–25 °C

Table 3.2

Liquid–liquid interfacial tensions (and liquid surface tensions) for some liquids. All values are given at room temperature (20 °C). Differences in miscibility in, for example, aqueous solutions with hydrocarbons, fluorocarbons or alcohols can be elucidated from the values of the interfacial tensions. The higher the interfacial tensions, the lower the miscibility. For alcohols smaller than butanol, the interfacial tensions with water are zero, as such alcohols are completely miscible in water. Fluorocarbons have among the lowest surface tensions due to their very weak van der Waals forces