Chemical Electrostatics: New Ideas on Electrostatic Charging: Mechanisms and Consequences PDF
Preview Chemical Electrostatics: New Ideas on Electrostatic Charging: Mechanisms and Consequences
Fernando Galembeck Thiago A. L. Burgo Chemical Electrostatics New Ideas on Electrostatic Charging: Mechanisms and Consequences Chemical Electrostatics Fernando Galembeck • Thiago A.L. Burgo Chemical Electrostatics New Ideas on Electrostatic Charging: Mechanisms and Consequences Fernando Galembeck Thiago A. L. Burgo Institute of Chemistry Departament of Physics University of Campinas Federal University of Santa Maria Campinas, São Paulo, Brazil Santa Maria, Rio Grande do Sul, Brazil ISBN 978-3-319-52373-6 ISBN 978-3-319-52374-3 (eBook) DOI 10.1007/978-3-319-52374-3 Library of Congress Control Number: 2017935479 © Springer International Publishing AG 2017 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Printed on acid-free paper This Springer imprint is published by Springer Nature The registered company is Springer International Publishing AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland This book is dedicated to Emoke Hársi Galembeck, loving and courageous companion on a long journey. Fernando Galembeck and To my mother and my father, for their love and dedication. Thiago A.L. Burgo Preface Electrostatics is now in its second decade of great activity that challenged well- established ideas substituting them for new concepts. As it often happens in science, this was made possible by new experimental tools like the scanning probe micro- scopes and scanning electrodes that produce 3D plots of charge, potential, capaci- tance, or conductance at solid and liquid surfaces. Another factor for change was the dissemination of other experimental tools like the noncontact electrostatic probes that measure electrostatic potential. Researcher attitudes also changed and many decided to follow a suggestion made by Whitesides, accepting that macroscopic systems under equilibrium or quasi-equilibrium states may carry excess charge thus producing finite electric potential in their vicinity. The triboelectric series is another concept that was chal- lenged, when macro- and microscopic potential maps showed that charge distribu- tion on insulator surfaces is nonuniform, often following fractal patterns. A major conceptual change is the recognition of the role of ions as charge carri- ers in a large number of important electrostatic phenomena. This is the result of many laboratory experiments and field results in different research disciplines, allowing researchers and engineers to benefit from a large amount of chemical knowledge to understand well-known but hitherto challenging phenomena. It is now possible to describe “space charge” in terms of ions and electrons, largely increas- ing the accuracy of the descriptions of the involved phenomena. The atmosphere was acknowledged as the site of many phenomena producing electricity and this is related to water that assumes a paramount role in electrostatic phenomena. Water was previously seen as an agent for the dissipation of charge on electrified surfaces, due to its weak but non-negligible conductivity. Opposite to that, its ability to impart charge to solid surfaces is now recognized and it is exten- sively discussed in Chap. 6 of this book, on Hygroelectricity. Triboelectricity is receiving a firmer mechanistic basis, since charge carriers in tribocharged polymers were identified as ionic species formed during mechanochemi- cal reactions. Coupled to the demonstration that charge abatement on electrified poly- mer surfaces is also related to water adsorption, it can now be much better studied. vii viii Preface Another contribution came from acknowledging that many important metals are coated with a layer of oxide with low intrinsic conductivity. This also helped to understand interesting electrostatic phenomena in isolated metal objects. The recent surge in the science of Electrostatics is thus due to new and often unexpected results that are being slowly examined, criticized, and absorbed by sci- entists and engineers. This new situation was not created by any bright new theory or by a single breakthrough that illuminated the way for scientists and engineers. For this reason, it is not easily captured by reading separate papers that contain a small but nevertheless essential part of the history. Moreover, there are a large num- ber of papers and reports on various phenomena that were not followed up in the literature, remaining as valuable but uncorrelated and often forgotten pieces of information. These papers come from many different scientific disciplines, with dif- ferent approaches, methodologies, and outlook. This book is a systematic presentation of recent developments in Electrostatics, emphasizing those that are really new additions to the many excellent books that treat this subject in a more formal and abstract way. Recent developments are cor- related to previously scattered experimental information that hitherto was consid- ered too empirical to be considered in reference books. Recent and previous information is reported and discussed with an emphasis on physico-chemical and chemical events, whose elucidation is providing a better understanding of Electrostatics. This is why this book is named Chemical Electrostatics. Some read- ers may miss the abundance of mathematical equations often found in books and book chapters on Electrostatics. This is a deliberate choice of the authors, who did not want to repeat the contents of previous, excellent books. Even though there is an emphasis on chemical and physico-chemical phenom- ena, chemical equations were kept to a minimum, acknowledging that chemical language is not familiar to many “hard” scientists and engineers. Well-established concepts are used throughout the book, like pK and zeta poten- tial, adsorption, electronegativity, electrical double layer, and many others that may not be familiar to some readers. The authors opted for not making specific introduc- tions to them because this would largely lengthen the text. Moreover, these concepts are treated in detail in many reference books and in valuable materials accessible through the Internet. The authors strongly encourage readers to get well acquainted with those more basic concepts, whenever they feel they need it. Chemistry made an invaluable contribution to our understanding of electrostatic phenomena and this will probably continue, for the foreseeable future. Chemistry is complex, the same as Nature. It is not amenable or properly explained by any encompassing theoretical approach; neither are most chemical phenomena predict- able by any single theory. Given the importance of chemical phenomena to Electrostatics, the same applies to this discipline. The authors expect that this phenomenological presentation will help researchers and engineers to devise new and better ways to reach some practical objectives. One is to increase human and property safety, avoiding undesirable consequences of electrostatic discharges, as discussed in Chap. 12. Chapter 13 presents new Preface ix functional materials that can perform currently or previously unimaginable tasks, added to new products and processes to better human life, in a greener world. Electrostatics has some appealing “green” features: large effects are produced using a few Joules, while great changes in the behavior of matter are obtained by adding or removing minute amounts of water. These features will allow Electrostatics to play a major role, in the quest for sustainability. Campinas, São Paulo, Brazil Fernando Galembeck Santa Maria, Rio Grande do Sul, Brazil Thiago A.L. Burgo Acknowledgements The authors are glad to acknowledge the support of: Unicamp students whose work formed the original basis for most ideas and con- cepts developed in this book: André Herzog, Camila Rezende, Elizângela Linares, Érico Teixeira-Neto, Carlos Costa, Carlos Leite, Fábio Bragança, Leandra Santos, Leonardo Valadares, Lia Balestrin, Lucas Soares, Márcia Rippel, Rubia Gouveia, and Telma Ducati; Pompeu Abreu-Filho, who organized the book chapters; Maria do Carmo V. M. da Silva, who kept the laboratory on its feet while research was done; The University of Campinas, where the major part of the work was done. For many years, critical discussions were held with many persons. Their criti- cism and support is acknowledged but they are not to be criticized for any disputed ideas presented in this book: André Assis (Campinas), André Galembeck (Recife), Brian Vincent (Bristol), Daniel Lacks (Cleveland, OH), Darrell Velegol (University Park, PA), David Waddington (York), Gerald Pollack (Seattle, WA), Kazue Kurihara (Sendai), Oswaldo Alves (Campinas), Ponisseril Somasundaran (New York), Tom Healy (Melbourne). Funds for equipment, fellowships, and laboratory running expenses were obtained from the Brazilian National Research Council (CNPq/MCTIC) and São Paulo State Research Foundation (Fapesp), who supported the Inomat project within the INCT (National Institutes for Science and Technology) program. Project num- bers are: CNPq 573644/2008-0 and Fapesp 2008/57867-8. Earlier support from CAPES (fellowships), CNPq (Millenium Institutes Program) and Fapesp (Projeto Temático) is also acknowledged. Excellent access to databases, journals, and other primary information materials was possible thanks to the Portal de Periódicos funded by Capes Foundation, from the Brazilian Ministry of Education. xi Contents 1 Living in an Electrified Environment .................................................... 1 1.1 The Earth Capacitor ......................................................................... 1 1.2 The Global Atmospheric Electrical Circuit ...................................... 2 1.3 Electricity Produced Within the Earth Capacitor ............................. 4 1.3.1 Local Current Transients Within the Earth Capacitor: Lightning ............................................................ 4 1.3.2 Coupling to Earthquakes ...................................................... 7 1.3.3 In Other Planets .................................................................... 7 1.4 Electricity in the Crust: The Self-Potential ...................................... 8 1.5 Human Perception of Environmental Electricity ............................. 8 1.6 Conclusions ...................................................................................... 9 References ................................................................................................. 10 2 Electroneutrality: When and Where? ................................................... 13 2.1 A Widespread Belief ........................................................................ 13 2.2 Charge Accumulation, Electrostatic Discharge ............................... 14 2.3 Electric Potential, Electric Field, Electrochemical Potential ........... 15 2.4 Taking Electroneutrality for Granted ............................................... 16 2.5 The Electroneutrality Principle ........................................................ 17 2.6 Pauling’s Principle of Electroneutrality ........................................... 18 2.7 Factors of Non-Electroneutrality ..................................................... 18 2.7.1 Dangling Bonds ................................................................... 18 2.7.2 Are Ionic Crystals Electroneutral? ....................................... 19 2.7.3 New Ion Sources for Mass Spectrometry ............................ 19 2.7.4 Contact Charging, Mechanochemistry, Tribochemistry ...... 20 2.7.5 Liquid Junction Potential and Membrane Potential ............. 21 2.7.6 Electrostatics in Chemical Processing ................................. 22 2.7.7 Electrostatics in Soft Matter ................................................. 22 2.8 Conclusions ...................................................................................... 23 References ................................................................................................. 23 xiii
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