ION EXCHANGE -- -- -- . • . . . - ) -- / Friedrich Helfferich ION EXCHANGE McGRAW -Hlll SERIESIN ADVANCED CHEMISTRY SENIOR ADVISORY BOARD W. Conard Fernelius Louis P. Hammett EDITORIALB OARD David N. Hume Gilbert Stork Edward L. I{ing Harold H. Williams John A. Pople Dudley R. Herschbach BAIR Introduction to Chemical Instrumentation BENSON The Foundations of Chemical Kinetics DAVIDSON Statistical Mechanics DAVYDO(VT rans. Kasha and Oppenheimer) Theory of '.\lolel'ul:ir Ex<"iton,; DEAN Flame Photometry DJERASSI Optical Rotatory Dispersion ELJEL Stereochemistry of Carbon Compounds FITl'S Nonequilibrium Thermodynamics HELFFERICH Ion Exchange HILL Statistical Mechanics RINE Physical Organic Chemistry KIRKWOODA NDO PPENHEIM Chemical Thermodynamics KOSOWER Molecular Biorhemistry LAITINEN Chemical Analysis PITZERA NDB REWER(R evision of Lewis and Randall) Thermodynamirs POPLE,S CHNEIDERA, NDB ERNSTEIN High-resolution Nuclear Magnetic Resonance PRYOR Mechanisms of Sulfur Reactions ROBERTS Nuclear Magnetic Resonance ROSSO'rl'AI NDR ossoTIT The Determination of Stability Com1tnnh; wmER0 Laboratory Technique in Organic Chemistry ION EXCHANGE Friedrich Helfferich SHELL DEVELOPMENT COMPANY, EMERYVILLE, CALIFORNIA LLCTURI:.:R AT THE UNIVBRSITY OF CALIFORNIA, BERKELEY 1962 New York San Francisco Toronto London McGraw-Hill Book Company, Inc. ION EXCHANGE Copyright © 1962 by the l\foGraw-Hill Book Company, Inc. All Rights Reserved. Printed in the United States of America. This book, or parts thereof, may not be reproduced in any form without permission of the publishers. Library of Congress Catalog Card Nwn ber 61-15453 28070 First published in the German language under the title "IONENAU STAUSCHER" and copyright 1959 by Verlag Chemie GmbH, Wein heim/Bergstr.o.sse, Germany. Preface Ion exchange is not a recent invention. For more than half a century ion exchangers have been used to an increasing extent both in the laboratory and in plant operations. The theory of ion exchange, however, is of a more recent. origin. Only in the course of the last fifteen years have detailed theories been developed from which a sound and consistent framework covering the most important aspects of ion exchange can be built. Thus it seems that. the time has come when a comprehensive treatise on ion exchange can be written. The main difficulty confronting such an endeavor is not that too lit.tie, but rather that too much is known about ion exchange. By now, the theories and experimental evidence are well in excess of what any author would dare to offer to his readers. Therefore I have consciously based this hook on a limited selection of theoretical approaches and experi­ mental results which appear to me to be suitable for giving a clear-cut picture of the phenomena and their physical causes. Rather than striving for completeness or emphasizing abstract theories, I have attempted to give tangible, but nevertheless quantitative, explanations of the "how" and "why." This book is intended to provide the reader with a sound under­ standing of the relevant factors in ion exchange and with the theoretical tools that might help him in solving his specific problems. The German edition of this book appeared in 1959 as the first volume in a series of which later volumes will deal with practical applications. The English edition includes a more detailed discussion of the various types of ion-exchange column operations. However, the emphasis has remained on general principles. No detailed prescriptions for particular applications have been included. The reader looking for advice on such details is referred to the literature. The German edition has, on occasion, been mildly criticized by exponents of the two extremes of the wide spectrum of users. A plant engineer and an organic chemist have complained that studying this book requires too much background in mathematics and theoretical physical chemistry. On the y YI PREFACE other hand, a scholar whose superior command of thermodynamics I greatly admire has expressed his concern with one or the other attempt to give too facile an explanation for a very complex phenomenon. These criticisms have prompted me to separate, where possible, the qualitative and the quantitative treatment even more sharply than in the German edition. The mathematically disinclined reader may now cheerfully skip all mathe matical equations and deductions without loss in continuity. The theo retical perfectionist will, I hope, excuse the sacrifice of rigor for the sake of simplicity in qualitative explanations and interpretations which were written for the benefit of his more pedestrian colleagues. In a book of this kind it is virtually impossible to mention all those who have contributed to the development and present knowledge of ion exchange. Quotations and literature references have been restricted to publications which are apt to illustrate the discussion in the text. The choice is, by necessity, a matter of the author's own views and preferences. l\Iay I be forgiven by those to whom I have not given due credit. The American publisher has entrusted me with the task of translating my own book. As English is not my native tongue, I must beg the reader':; forbearance regarding my style. My sincerest thanks are due to the many experts who have contributed to this book with helpful suggestions and constructive criticism. It is a pleasure to acknowledge the valuable help of Dr. G. E. Boyd in revising the English manuscript. Furthermore, I am particularly indebted to D1·. H. Schlogl, Dr. G. Scatchard, Dr. K S. Spiegler, Dr. T. Yermeulen, Dr. E. Glueckauf, Dr. R. M. Barrer, Dr. l:. Schindewolf, and Dr. R. E. ::\Ieeker, and to A. K. Dunlop who struggled valiantly with my style. Friedrich G. Heljfericl, Contents Preface . V Introduction s 1. Elementary Princ;iples. 2. Strudure and Properties of Ion Eltchangen 10 2-1. Mincrnl Ion Exchangers 10 2-2. Synthetic Inorganic Ion Exchangers . 12 2-:J. Ion-exchange Resins 14 2-4. Jon-exchnnge Conls. 17 2-5. Other Materials with Ion-exchange Properties 18 2-6. Liquid Ion Exchangers . 19 2-7. Survey and Comparison 20 Summary 20 References . 21 3. Preparation 26 3-1. Principles. 27 3-2. Cation Exchangers . 29 3-3. Anion Exchangers . 47 3-4. Amphoteric Ion Exchangers 58 3-5. Particle Shape and Size, Macroretieular Resins, and Supported Ion Exchangers . 59 3-6. Ion-exchanger Membranes. 61 Summary 65 References 66 4. Capac:ity . 72 4-1. Definitions nnd Units . 72 4-2. Apparent Capacity and Its Dependence on Experimental Conditions 79 4-3. pH Titration. 81 4-4. Determination of pK Values 84 4-5. Experimental Methods. 90 Smnmary 93 References . 94 "'' viii CONTENTS 5. Equilibria 95 5-1. Theoretical Approaches and Models . 96 5-2. Swelling . 100 5-3. Sorption of Solutes . 125 5-4. Ion-exchange Equilibria 151 5-5. Systems with More Than Two Counter-ion Species 200 5-6. Ion-exchange Equilibria In,·olving Complexing Agents. 202 5-7. "Ligand Exchange". 222 5-8. Reactions with Materials of Low Solubility . 226 5-9. Experimental Methods. 229 Summary 239 Refe reru:e, 242 6. Kinetics 250 6-1. Mechanism of Ion Exchange 250 6-2. The Rate-determining Step 252 6-3. Rate Laws of Ion Exchange 25i 6-4. Empirical and Simplified Rate Laws . 286 6-5. Systems with More Than Two Counter-ion Species 288 6-6. IGnetics of Sorption and Swelling. 289 6-7. Reactions with Materials of Low Solubility. 2Hii 6-8. Diffusion Coefficients in Ion Exchangers. 2\19 6-9. Experimental Methods. :mu Summary :iii Reference, . :JI !I 7. ElectrochemicaPl roperties 323 7-1. Electric Conductivity a:?a 7-2. Transference Numbers and Transport Numbers :326 7-3. Transference of Solvent; Convection Conductivity. :t?i 7-4. Quantitative Relations . :J2S 7-6. Experimental Methods. 3:J3 Summary 3:rn References :i:m 8. Ion-exchanger Membn,nes 339 8-1. Characteristic Properties of lon-exchanp:cr Mrmbrnncs 3-10 8-2. Models and Theoretical Approaches . :wi 8-3. Diffusion acroS!JM embranes . :J-1.'i 8-4. Membrane Potentio.ls . :ms 8-5. General lntegrntion of the Ncrnst-Plnnck Ec1untio11R 38/j 8-6. Anomalous Osmosis. :nm 8-7. Streaming Potential, Streaming Current, nnd Electrolyte J,'iltration 3BI 8-8. Transport of Electric Current. across Memhrnncs 397 8-9. Sorting Effects . 408 8-10. Experimental Methods. -109 Summary 414 References . 4 Ii 9. Ion-exchangeC olumns 421 9-1. Ion Exchange in Columns . 422 9-2. Conventional Column Operation 428 CONTENTS ix 9-3. Two-stage, Multistage, nnd Mixed-bed Deionization 430 9-4. Ion Exclusion 431 9-5. Ion Retardation. 433 9-6. Separation by Selective Displacement 434 9-7. Principles of Ion-exchange Chromatography. 436 U-8. "Ligand Exchange" and Other Techniques Bused on Chemical Reactions 445 !J-9. Quantitative Treatment 447 9-10. Hydrodynamic und Thermochc>mical Effects. 485 9-11. Electrochemical Properties. 489 9-12. Experimental Methods. 493 Summary 495 Refe re11ces 499 10. Behavior in Nonaqueous and Mixed Solvents 507 10-1. Ion Exchange in Nonaqueous Systems 508 10-2. Swelling . 509 10-3. Capacity . 512 10---1. Ion-exchange and Sorption Equilibria 513 10-5. Kinetics . 515 10-6. Electrochemicnl Properties. 516 Sr,111111ary 517 Rrfcre"nccs 517 11. Catalysis by Ion Exchangers 519 I 1-l. Henctions of Gases and Vapors 519 11-2. Reactions of Liquids and Solutes. 522 11-:J. I·Gnelics . 524 11--l. Experimental l\Iethods. 547 Siimmary 548 Rcfe re11ces . 549 12. Electron Exchangers and Redox Ion Exchangers . 551 12-I. Preparation . 552 12-2. Heactions und Applications 556 12-3. Physicochemical Properties 559 12--l. Experimental Methods. 565 Summary 567 Refe re11crs 567 Appendix 569 Symbols, Abbreviations, and Units 569 Commercial Ion Exchangers . 574 Tables of Mathematical Functions 584 Name Index 591 Subject Index 603