Ion Exchange and Solvent Extraction: A Series of Advances, Volume 15 PDF
Preview Ion Exchange and Solvent Extraction: A Series of Advances, Volume 15
Ion Exchange and Solvent Extraction Ion ExchanCJe and Solvent Extraction AS eries of Advances Volume 15 edited by Yizhak Marcus The Hebrew University of Jerusalem Jerusalem, Israel Arup K. SenGupta Lehigh University Bethlehem, Pennsylvania Jacob A. Marinsky Founding Editor Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Group, an informa business First published 2002 by Marcel Dekker, Inc. Published 2018 by CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW; Suite 300 Boca Raton, FL 33487-2742 © 2002 by Taylor & Francis Group, LLC CRC Press is an imprint ofTaylor & Francis Group, an Informa business No claim to original U.S. Government works ISBN 13: 978-0-8247-0601-2 (hbk) This book contains information obtained from authentic and highly regarded sources. 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For permission to photocopy or use material electronically from this work, please access www. copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Voit the Taylor &: Francis Web site at http://www.taylorand&ancis.com and the CRC Press Web site at http://www.crcpress.com Preface The fifteenth volume of Ion Exchange and Solvent Extraction is concerned with the advances in solvent extraction, a field that also was covered in volume 13. This book was conceived at ISEC 1999, the International Solvent Extraction Conference, held in Barcelona, Spain. Several authors responded to the call by the editors to contribute comprehensive review chapters on subjects in which they are experts and in which important advances have been noted in recent years. In such diverse industrial fields as hydrometallurgy, pharmaceutical chem istry, organic fine chemicals, and biotechnology, there are new applications of solvent extraction. These are based on research conducted in laboratories all over the world, leading to the development of viable and profitable processes. Both basic research and process development are the keys to success in this field, and this volume addresses the need for persons active in the field of solvent extraction to learn of the advances made in it. These often occur rapidly, and it is expected that further advances, based partly on those presented here, will be discussed at the next International Solvent Extraction Conference, ISEC 2002, to be held in Cape Town, Republic of South Africa. Chapter 1, dealing with an integrated method for the development and scaling up of extraction processes, is actually a manual for practitioners, both novices and experienced. It is written in a conversational manner, presenting sound procedures to be followed and cautions against pitfalls; it also provides detailed examples of actual processes that have been developed. Several sections include the important advice that in some cases the developer should tell the person who commissioned the work that solvent extraction is not the method that should be used for the separation job. In many other cases, however, solvent extraction can be used profitably, if the proper solvent and equipment are st ill iv Preface lected, on the basis of laboratory, bench-scale piloting, and full-scale piloting experiments, based on and backed-up by the proper simulation work. These are fully described in Chapter 1. Chapter 2 is concerned with the design of pulsed extraction columns, one of the options discussed in Chapter 1. This design requires time-consuming and expensive laboratory-scale or pilot-plant experiments, in particular if de tailed information on the drop-size distribution and/or the holdup profile of the dispersed phase is needed. The sensitivity of the mass transfer to even low concentrations of impurities mandates experiments with the real mixture in order to obtain reliable data for designing a technical column. Since the design cannot proceed from first principles, a “standard apparatus” was developed that allowed the measurement of the required data, based on a population-balance model. It permitted the determination of the rising velocity of single drops, the breakup of drops, the coalescence of drops, and the mass transfer coefficient of a drop under the conditions to be expected for the technical column. The excellent agreement between simulated and experimental data confirms the suit ability of the design concept. An implicit implementation of the development and scaling up of ex traction processes, as outlined in Chapter 1, is seen in Chapter 3, on the purification of nickel by solvent extraction. Chapter 3 shows that industry has adopted solvent extraction as the major production method for nickel, replacing pyrometallurgical processes, at least in the stages concerned with purification of nickel from other base metals. This advance was made possible by the recent availability of commercial quantities of selective extractants as well as the dem onstrated successful operation of large-scale solvent extraction plants. Modern flow sheets thus permit profitable recovery of highly pure nickel even from low grade ores, as well as the capture of high-purity cobalt as a by-product. Another application of solvent extraction on an industrial scale is the clean up of contaminated soils and sludges, described in Chapter 4. The application of this technology to environmental problems appears to be gaining more wide spread acceptance. This acceptance comes in spite of the justified criticism that inappropriate use of solvents in industry, including their use in solvent extrac tion, adds to the contamination of the environment. When a proper choice of solvents is made, this technology becomes viable for the cleaning up the envi ronment. The processes that have been proposed and tested on a commercial scale are reviewed, and their acceptance by the regulatory authorities is discussed. As explained in Chapter 1, the choice of the appropriate solvent for a given separation job by solvent extraction is the key problem in this technology. For the short term, commercially available solvents must be employed, even if their properties are not optimal. However, in the long run, in particular for highly specialized separation jobs, it is important to design new solvents with Preface v optimized properties for a given separation. How to design solvents with their ultimate use in mind is fully discussed in Chapter 5. In one sense, this chapter supplements the procedures recommended in Chapter 1 by providing the needed screening criteria. In another sense, the design of new solvents is a challenge met by the methodology described in Chapter 5. Computer-aided molecular design is invoked, including interactive, combinatorial, construct- and-test, and mathematical programming methods. The evolutionary approach to designer solvents is then discussed in detail, showing all its advantages, and is illustrated by the design of a solvent for the separation of phenols from neutral oils. The emphasis in developments in solvent extraction has shifted in recent years from the more venerable fields of nuclear fuel reprocessing and hydro metallurgy to the separation of organic substances. A tough problem in this field, of particular relevance for pharmaceutical chemistry and biotechnology, is the separation of optical isomers, only one type of enantiomer is biologically active. The difficulty arises because the differences in the extractabilities of the species formed with suitable extractants are minute. The attempts that have been made to solve this problem are described in Chapter 6. If a solvent ex traction method for the separation of the enantiomers is to be developed the chiral recognition mechanisms must be understood. The design of a multistage process appears to be necessary, and the solutions proposed so far for this problem are discussed, the absence of the use of extraction columns being conspicuous in this respect. Most of the known solvent extraction processes take place between an aqueous feed and an organic solvent/extractant that, to ensure low miscibility with the aqueous solution, is necessarily of low polarity. An exception, discussed fully in Volume 13 of this series, is the use of an aqueous solution of poly ethylene glycols opposing a concentrated aqueous electrolyte solution in a bi- phasic aqueous extraction system. Water-miscible polar organic solvents, com monly used in electrochemistry or analytical chemistry, such as the lower alcohols, A^,A^dimethylformamide, acetonitrile, and dimethyl sulfoxide, have therefore been excluded from consideration in solvent extraction systems. This situation is now reversed, as shown in Chapter 7. It is shown that such solvents or their aqueous solutions can be successfully used when opposed to a nonpolar hydrocarbon to separate hydrophobic solutes by liquid-liquid distribution. The solutes include higher alcohols, long-chain amines, quatenary ammonium salts, nitroalkanes and nitriles, phosphoric acid esters, and terpenoid derivatives. The regularities governing such systems are explored, to enable the prediction of the best choice of solvent for a given separation problem. Finally, Chapter 8 is devoted to a solvent extraction concept completely different from that discussed in the earlier chapters (mainly 1—3)—that is, nondispersive, membrane-based liquid—liquid distribution systems. In certain vi Preface situations, mixer-settlers or columns, based on the dispersion of the two im miscible liquid phases in each other before being separated again, have not been sufficiently successful, and an alternative has been sought. Since the advent of commercially available hollow-fiber modules, among other porous-membrane- based devices, nondispersive methodologies have become attractive for use in such situations. Laboratory- and pilot-plant-scale studies of membrane-based liquid—liquid extraction systems are described, as are the modeling of such systems and the evaluation of the mass transfer coefficients. Some specialized applications, already in an advanced stage of implementation, include proce dures used by the beverage and semiconductor industries. The wide gamut of topics covered in these eight chapters attests to the diversity of the solvent extraction methodology and its applicability to separa tion technology in many industries. This volume is also evidence of the con tinuing advances in this field being contributed by laboratories and industrial research organizations all over the globe. Few readers will fail to find infor mation or insight that will make their effort worthwhile. Yizhak Marcus Arup K SenGupta Contributors to Volume 15 Richard J. Ayen Neptune Consulting, Wakefield, Rhode Island Peter M. Cole Hydrometallurgy Consultant, Bryanston, South Africa Andre B. de Haan Faculty of Chemical Technology, Twente University, En schede, The Netherlands Baruch Grinbaum IMI (TAMI) Institute for Research and Development Ltd., Haifa, Israel Hartmut Haverland Gebriider Lodige Maschinenbau GmbH, Paderborn, Germany Sergey M. Leschev Analytical Chemistry Department, Belarusian State Uni versity, Minsk, Republic of Belarus James D. Navratil Environmental Engineering and Science, Clemson Uni versity, Anderson, South Carolina Izak Nieuwoudt Department of Chemical Engineering, Institute for Thermal Separation Technology, University of Stellenbosch, Stellenbosch, South Africa Anil Kumar Pabby PREFRE Plant, Nuclear Recycle Group, Bhabha Atomic Research Centre, Tarapur, Maharashtra, India vii
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