Selectivity scale for cations

Selectivity Scale for Cations on 8% Cross-linked Strong-Acid Resin and for Anions on Strong-Base Resins... 

F. W. E. Strelow, R. Rethemeyer, and C. J. C. Bothma, Ion exchange selectivity scales for cations in nitric acid and sulfuric acid with a sulfonated polystyrene resin. Ana/. Chem., 31. 106. 196. 

O. D. Bonner and L. L. Smith, A selectivity scale for some bivalent cations on Dowex 50, J. Phys. Chem.,61,326,1957. 

A selectivity scale for divalent cations is given in Table 13.1-4, Again the arbitrary value of unity is given to the lithium ion, Bonner and Smith corrected their value of the equilibrium constant by allowing for activity coefficients by using the method developed by Argersinger and Davidson.7 Thus,... 

It has been emphasized repeatedly that the individual activity coefficients cannot be measured experimentally. However, these values are required for a number of purposes, e.g. for calibration of ion-selective electrodes. Thus, a conventional scale of ionic activities must be defined on the basis of suitably selected standards. In addition, this definition must be consistent with the definition of the conventional activity scale for the oxonium ion, i.e. the definition of the practical pH scale. Similarly, the individual scales for the various ions must be mutually consistent, i.e. they must satisfy the relationship between the experimentally measurable mean activity of the electrolyte and the defined activities of the cation and anion in view of Eq. (1.1.11). Thus, by using galvanic cells without transport, e.g. a sodium-ion-selective glass electrode and a Cl -selective electrode in a NaCl solution, a series of (NaCl) is obtained from which the individual ion activity aNa+ is determined on the basis of the Bates-Guggenheim convention for acr (page 37). Table 6.1 lists three such standard solutions, where pNa = -logflNa+, etc. 

Various types of cationic surfactants were reviewed by us to select one, relatively low in cost and readily prepared on a large scale, for which the relationship of chemical structure to surface active properties could be conveniently studied. 

Graphical integration methods are used to evaluate equations 5.26 and 5.27 which thus establish a scale for selectivity in ion exchangers. A typical selectivity series for some common cations on a sulfonic acid resin exchanging against Li is shown in Table 5.2. 

TABLE 13.1-4 Selectivity (ffj Scale for Divalent Cations in Selfonic Acid Resfus Using the Lithium Ion as Reference... 

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