Theory and Practice of Ion Exchange

Constituent of concern Chemical designation Resultant problems 

Hardness Calcium and magnesium salts in the forms of CaCOj, Ca, Mg. This is the primary source of scaling in heat exchange equipment, boilers, pipelines/transfer lines, etc. Tends to form curds with soap and interferes with dyeing applications as well. 

Alkalinity Bicarbonate (HCO3), carbonate (CO3), and hydrate (OH), expressed as CaCOj. Causes foaming and carryover of solids with steam. Can cause embrittlement of boiler steel. Biocarbonate and carbonate generate COj in steam, a source of corrosion. 

Free mineral acidity H2SO4, HCl, and other acids, expressed as CaCOj. Causes rapid corrosion and deterioration of surfaces. 

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The Theory and Practice of Ion Exchange , ed. M. Streat, Society of Chemical Industry, London, 1976, Conf. Proc. (Cambridge). 

Boschetti, E., and Girot, P. (2000). Ion exchange interaction biochromatography. In Theory and Practice of Biochromatography (M. A. Vijiayalakshmi, ed.), Harwood Academic Publishers, Chur, Switzerland, (in press). 

This chapter considers the theory and practice of HPLC, including partition, adsorption, ion-exchange, size-exclusion, affinity, and chiral chromatography. HPLC has applications not only in forensics but also in biochemistry, environmental science, food science, pharmaceutical chemistry, and toxicology. 

Some typical separations carried out by ion-exchange chromatography in the field of Organic Chemistry have already been cited earlier in the present chapter as illustrations in aid of the discussion of the theory and practice of this separation technique. The use of ion-exchange chromatography in the realm of Inorganic Chemistry may be illustrated with some typical separations belonging to that field. 

There are three basic concepts that explain membrane phenomena the Nemst-Planck flux equation, the theory of absolute reaction rate processes, and the principle of irreversible thermodynamics. Explanations based on the theory of absolute reaction rate processes provide similar equations to those of the Nemst-Planck flux equation. The Nemst-Planck flux equation is based on the hypothesis that cations and anions independently migrate in the solution and membrane matrix. However, interaction among different ions and solvent is considered in irreversible thermodynamics. Consequently, an explanation of membrane phenomena based on irreversible thermodynamics is thought to be more reasonable. Nonequilibrium thermodynamics in membrane systems is covered in excellent books1 and reviews,2 to which the reader is referred. The present book aims to explain not theory but practical aspects, such as preparation, modification and application, of ion exchange membranes. In this chapter, a theoretical explanation of only the basic properties of ion exchange membranes is given.3,4... 

Different t) es of cation-exchange resins have been employed for homemade argentation, such as the RSilCAT, Nucleosil 5SA, Spherisorb 5SCX, and Partisil SCX nowadays, Ag-coated columns are commercially available. However, the actual silver-ion content of such coliunns is not known exactly and cannot be controlled. The munber of functional groups bound to the silica surface and the degree of replacement of the initial cation with Ag affect the separation and its reproducibility. Mobile phases employed for Ag LC typically consist of hexane, toluene, or dichloromethane—dichloroethane mixtures. The theory and practice of silver-ion LC have been thoroughly reviewed [52]. 

The historical development of chemically electrodes is briefly outlined. Following recent trends, the manufacturing of modified electrodes is reviewed with emphasis on the more recent methods of electrochemical polymerization and on new ion exchanging materials. Surface derivatized electrodes are not treated in detail. The catalysis of electrochemical reactions is treated from the view of theory and of practical application. Promising experimental results are given in detail. Finally, recent advances of chemically modified electrodes in sensor techniques and in the construction of molecular electronics are given. 

C. E. Harland, Ion Exchange Theory and Practice. Cambridge, U.K. The Royal Society of Chemistry, 1994. 

Step 3. Read about the radiochemistry of iodine to improve your understanding of the radioanalytical chemistry of iodine. An old but helpful monograph is Radio chemistry of Iodine, NAS-NS-3062, by Milton Kahn and Jacob Kleinberg, Office of Scientific and Technical Information, US DOE, 103 pp (1977). A copy may be obtained from the instructor, the library, or internet search. Also read about ion-exchange theory and practice, and in particular, the relative affinity of anions for strong-base ion-exchange material. 

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