Table Of Content

Introduction to Colloid and Surface Chemistry To Ann Introduction to Colloid and Surface Chemistry Fourth Edition Duncan J. Shaw, esc, Phd, FRSC Formerly Principal Lecturer in Physical Chemistry, Department of Chemistry and Biochemistry, Liverpool Polytechnic U T T E R W O R TH E I N E M A N N OXFORD AMSTERDAM BOSTON LONDON NEW YORK PARIS SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO Butterworth-Heinemann An imprint of Elsevier Science Linacre House, Jordan Hill, Oxford OX2 8DP 200 Wheeler Road, Burlington, MA 01803 First published 1966 Reprinted 1968 Second edition 1970 Reprinted 1975, 1976, 1978, 1979 Third edition 1980 Reprinted 1983, 1985, 1986, 1989 Fourth edition 1992 Reprinted 1992, 1993, 1994 (twice), 1996, 1997, 1998, 1999, 2000 Transferred to digital printing 2003 Copyright © 1992, Elsevier Science Ltd. All rights reserved No part of this publication may be reproduced in any material form (includ- ing photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England WIT 4LP. Applications for the copyright holder's written permission to reproduce any part of this publication should be addressed to the publisher British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloguing in Publication Data A catalogue record for this book is available from the Library of Congress ISBN 07506 11820 For information on all Butterworth-Heinemann Publications visit our website at www.bh.com Printed and bound in Great Britain by Antony Rowe Ltd, Eastbourne Contents Preface vii 1. The colloidal state 1 Introduction 1 Classification of colloidal systems 3 Structural characteristics 6 Preparation and purification of colloidal systems 10 2. Kinetic properties 21 The motion of particles in liquid media 21 Brownian motion and translational diffusion 23 The ultracentrifuge 31 Osmotic pressure 37 Rotary Brownian motion 44 3. Optical properties 46 Optical and electron microscopy 46 Light scattering 53 4. Liquid-gas and liquid-liquid interfaces 64 Surface and interfacial tensions 64 Adsorption and orientation at interfaces 76 Association colloids-micelle formation 84 Spreading 93 Monomolecular films 96 5. The solid-gas interface 115 Adsorption of gases and vapours on solids 115 Composition and structure of solid surfaces 136 vi Contents 6. The solid-liquid interface 151 Contact angles and wetting 151 Ore flotation 161 Detergency 163 Adsorption from solution 169 7. Charged interfaces 174 The electric double layer 174 Electrokinetic phenomena 189 Electrokinetic theory 199 8. Colloid stability 210 Lyophobic sols 210 Systems containing lyophilic material 234 Stability control 241 9. Rheology 244 Introduction 244 Viscosity 245 Non-Newtonian flow 252 Viscoelasticity 256 10. Emulsions and foams 262 Oil-in-water and water-in-oil emulsions 262 Foams 270 Problems 277 Answers 287 References 290 Index 298 Preface This book has been written to fill a gap in the literature by offering a standard and overall coverage of colloid and surface chemistry intermediate between the brief accounts found in most textbooks of physical chemistry and the comprehensive accounts found in special- ised treatises on colloid and/or surface chemistry. In writing the book, I have kept a number of audiences in mind - particularly: university and polytechnic students studying for an honours degree or its equivalent, or commencing a programme of postgraduate research; scientists in industry who desire a broad background in a subject which may have been somewhat neglected during academic training; and those interested in branches of natural science, for whom an understanding of colloid and surface phenomena is essential. The subject matter is, in general, approached from a fundamental angle, and the reader is assumed to possess a knowledge of the basic principles of physical chemistry. Opportunities have also been taken to describe many of the practical applications of this subject. In addition, some numerical problems (with answers) and a list of references for further reading (mainly books and review articles) are given at the end of the book. The general character of this fourth edition is similar to that of the third edition. The text has been revised and updated throughout, the major change being the extension of Chapter 5 to include a section on the composition and structure of solid surfaces. I wish to thank my colleagues, particularly Dr A.L. Smith, for their many helpful suggestions, and my wife, Ann, for her help in preparing the manuscript and checking the text. DJ.S. Southport, 1991 This page intentionally left blank 1 The colloidal state Introduction Colloid science concerns systems in which one or more of the components has at least one dimension within the nanometre (10-9m) to micrometre (lO-"m) range, i.e. it concerns, in the main, systems containing large molecules and/or small particles. The adjective 'microheterogeneous' provides an appropriate description of most colloidal systems. There is, however, no sharp distinction between colloidal and non-colloidal systems. The range of colloidal systems of practical importance is vast, as is the range of processes where colloidsurface chemical phenomena are involved. Examples of systems which are colloidal (at least in some respects) are: Aerosols Foodstuffs Agrochemicals Ink Cement Paint Cosmetics Paper Dyestuffs Pharmaceuticals Emulsions Plastics Fabrics Rubber Foams Soil Examples of processes which rely heavily on the application of colloid/surface phenomena are: Adhesion Ore flotation Chromatography Precipitation Detergency Road surfacing