Provides a comprehensive introduction to ion exchange for beginners and in-depth coverage of the latest advances for those already in the field
As environmental and energy related regulations have grown, ion exchange has assumed a dominant role in offering solutions to many concurrent problems both in the developed and the developing world. Written by an internationally acknowledged leader in ion exchange research and innovation, Ion Exchange: in Environmental Processes is both a comprehensive introduction to the science behind ion exchange and an expert assessment of the latest ion exchange technologies. Its purpose is to provide a valuable reference and learning tool for virtually anyone working in ion exchange or interested in becoming involved in that incredibly fertile field.
Written for beginners as well as those already working the in the field, Dr. SenGupta provides stepwise coverage, advancing from ion exchange fundamentals to trace ion exchange through the emerging area of hybrid ion exchange nanotechnology (or polymeric/inorganic ion exchangers). Other topics covered include ion exchange kinetics, sorption and desorption of metals and ligands, solid-phase and gas-phase ion exchange, and more.
* Connects state-of-the-art innovations in such a way as to help researchers and process scientists get a clear picture of how ion exchange fundamentals can lead to new applications
* Covers the design of selective or smart ion exchangers for targeted applications--an area of increasing importance--including solid and gas phase ion exchange processes
* Provides in-depth discussion on intraparticle diffusion controlled kinetics for selective ion exchange
* Features a chapter devoted to exciting developments in the areas of hybrid ion exchange nanotechnology or polymeric/inorganic ion exchangers
Written for those just entering the field of ion exchange as well as those involved in developing the "next big thing" in ion exchange systems, Ion Exchange in Environmental Processes is a valuable resource for students, process engineers, and chemists working in an array of industries, including mining, microelectronics, pharmaceuticals, energy, and wastewater treatment, to name just a few.
Arup K. SenGupta, PhD is the P.C. Rossin Professor in the Department of Civil and Environmental Engineering and Department of Chemical Engineering at Lehigh University. Over the last 35 years he has studied, learned, taught and conducted extensive research into nearly every facet of ion exchange. Dr. SenGupta is recognized as the inventor of hybrid ion exchange nanotechnology (HIX-Nano) that offers enhanced separation through the Donnan Membrane Principle. HIX-Nano materials are currently in use in six different countries including the USA to remove arsenic, fluoride and phosphate from contaminated water and waste water. In 2004, Dr. SenGupta received the International Ion Exchange Award at Cambridge University in England. He was the North American Editor of the Reactive and Functionalized Polymers Journal from 1996-2006.
Ion Exchange and Ion Exchangers: An Introduction
1.1 Historical Perspective
Evolution is traditionally viewed to occur in a slow but continuous manner for living organisms and creatures gradually acquiring new traits. To the contrary, many areas of "science" undergo periods of rapid bursts of fast development separated by virtual standstill with no significant activity. The first historically recorded use of ion exchange phenomenon is from the Old Testament of the Holy Bible in Exodus 15:22-25 describing how Moses rendered the bitter water potable by apparently using the process of ion exchange and/or sorption. Another often quoted ancient reference is to Aristotle's observation that the salt content of water is diminished or altered upon percolation through certain sand granules. From a scientific viewpoint, however, the credit for recognition of the phenomenon of ion exchange is attributed to the English agriculture and soil chemists, J.T. Way and H.S. Thompson. In 1850, these two soil scientists formulated a remarkably accurate description of ion exchange processes in regard to removal of ammonium ions from manure by cation exchanging soil [1, 2]. They essentially simulated the following naturally occurring cation exchange reactions as follows: 1.1 1.2
Some of the fundamental tenets of ion exchange resulted from this work: first, the exchange of ions differed from true physical adsorption; second, the exchange of ions involved the exchange in equivalent amounts; third, the process is reversible and fourth, some ions were exchanged more favorably than others.
As often with many groundbreaking inventions, the findings of Way and Thompson cast doubts, disbeliefs and discouragement from their peers. In the following years, these two soil scientists discontinued persistent research in this field. As a result, the evolution of ion exchange process progressed rather slowly due to the difficulties in modifying or manipulating naturally occurring inorganic clayey materials with low cation exchange capacities.
Inorganic zeolites (synthetic or naturally occurring aluminosilicates) later found wide applications in softening hard waters, that is, removal of dissolved calcium and magnesium through cation exchange. However, the anion-exchange processes remained unexplored and practically unobserved. Even at that time, it was not difficult to conceptualize that the availability of both cation exchangers and anion exchangers in the ionic forms of hydrogen and hydroxyl ions, respectively, would create a new non-thermal way to produce water free of dissolved solids as indicated below: 1.3
The biggest obstacle to realize this concept was to identify and/or synthesize ion exchangers which will be chemically stable and durable under the chemically harsh environments at very high and low pH. The immense potential of ion exchange technology scaled a new height when the first organic-based (polymeric) cation exchanger was synthesized by Adams and Holmes . In less than ten years, D'Alelio prepared the first polymeric, strong/weak cation and anion exchangers [4-6]. Since then, synthesis of new ion exchangers never seemed to slow down and application of ion exchange technology in industries as diverse as power utilities, biotechnology, agriculture, pharmaceuticals, pure chemicals, microelectronics, etc. are continually growing. No specialty grows in isolation; ion exchange fundamentals, ion exchange resins and ion exchange membranes continue to find new and innovative applications globally. Figure 1.1 includes the number of ion exchange related US patents issued during the last three decades, illustrating continued inventions in new products and processes.
Figure 1.1 Number of patents per year for "anion exchange" and "cation exchange" per a Google Patents search.
Source: Data taken with permission from Google [7, 8].
Ironically, the Second World War and, more specifically, the race for nuclear technology helped catalyze the growth and maturity of the field of ion exchange at an accelerated pace. Ion exchange was found to be a viable process for separating some of the transuranium elements and, for understandable reasons, its application aroused a great deal of interest. In fact, some of the most fundamental works on ion exchange equilibria and kinetics were carried out during the Second World War period by Boyd et al. and reported afterwards in the open literature [9-11]. All along, the scientific understanding of ion exchange fundamentals consistently lagged well behind its applications. Table 1.1 attempts to summarize milestones in regard to the development and application of ion exchange technology over time.
Table 1.1 Historical milestones in ion exchange
Year Description Patent # Authors 1850 Discovery of ion exchange properties of soil N/A Thompson and Way [1, 2] 1876 Zeolites or aluminosilicates recognized for base exchange and equivalence of exchange is proved N/A Lemberg [12, 13] 1906-1915 Industrial manufacture of sodium permutit for hardness removal 914,405;
1,131,503 Gans  1934 Invention of sulfonated condensation polymers as cation exchangers 2198378A Ellis 1935 First synthetic organic ion exchangers 2104501A,
2151883A Adams and Holmes  1938 Mixed-bed ion exchange process or duplex ion exchanger 2275210A Stemen, Urbain, and Lewis 1939 Invention of sulfonated polystyrene polymerization as cation exchangers
Invention of aminated polystyrene polymerization as anion exchangers 2283236A
Vernal 1942 Cation exchange resin beads made from polymerized acrylic acids
Cation exchange resins with sulfonated, polymerized poly-vinyl aryl parent resin
Anion exchange resins with aminated, polymerized poly-vinyl aryl parent resin 2340110A, 2340111A
2366008A D'Alelio 1947 Element 61 (Promethium) was discovered by ion exchange of the by-products of fission N/A Marinsky, Glendenin, and Coryell  1953 Use of zeolites as molecular sieves
Magnetic ion exchange resin for NOM removal (MIEX process)
Invention of weak acid cation exchangers
First countercurrent ion exchange using suspended/agitated beds of resin 2882243A
Swinton and Weiss  1954 Higgins countercurrent ion exchange contactor invented 2815322A Higgins  1955 Ligand exchange 2839241A Albisetti 1956 Pellicular ion exchange resin 2933460A Richter and McBurney 1958 Agitated bed contactor for semicontinuous ion exchange
Ion exchange in drug delivery N/A
2990332A Arden, Davis, and Herwig 
Keating 1958 (publicly released) Uranium separation, intraparticle diffusion (Manhattan Project) 2956858A Powell 1959-1960 The book on "Ion Exchange" by Friedrich Helfferich was printed and laid the theoretical foundations for the field of ion exchange N/A Helfferich  1962-1971 Cloete-Streat countercurrent contactor invented 3551118A (1962)
3957635A (1971) Cloete and Streat  1964 Cellulosic ion exchange fibers synthesized 3379719A Rulison 1965 Sirotherm process - thermally regenerable ion exchange resins 274-029; 59,441/65
(Australia) Bolto, Weiss, and Willis Partially functionalized cation exchange (shallow-shell technology) 3252921A Hansen and McMahon 1966 Macroporous ion exchange resin 3418262A Grammont and Werotte 1968 Boron selective resin 20110108488A1 Chemtob 1969 Development of poly(methyl methacrylate) anion exchange resins or macroreticular polymers that reduced fouling by natural organic manner N/A Kressman and Kunin [22, 23] 1971 Continuous moving bed ion exchange 3751362A Probstein, Schwartz, and Sonin 1972 Phenolic ion exchange fibers 3835072A Economy and Wohrer 1973 Iminodiacetic acid chelating resin