Argensinger Method

3 Ion Exchange Analysis and Parameter Computation 5.3.3.1 Argensinger Method 

We will now consider some actual examples of ion exchange to illustrate the concepts discussed so far and introduce some more aspects. Most of the examples are of binary exchange, as presented in Equation 5.14 despite that in nature soil colloids are always in the presence of a soil solution containing a number of different anions and cations (see Chapter 7), most studies have been confined to binary cases. In general, the sample is first homoionized, that is, saturated with a single ion, either by repeatedly placing the sample in contact with fresh solutions of the ion of interest or by column leaching with an appropriate solution of such ion. 

Because here we have univalent cations, equivalent and molar fractions are the same, but for heterovalent exchange, both fraction types can be found (see below). Of course both plots are mirror images around the diagonal, because = 1. The 

We will now discuss the computation of from these results. As we have seen in Section 5.3.1, following Argersinger, Davidson, and (Bonner 1950), the following integral should be computed  

FIGURE 5.7 Homovalent K+-Na+ exchange on a Brucedale subsoil (Bond 1995) at I = 0.05 M. (a) Measured exchange isotherms open symbols—K+ mole fraction, closed symbols—Na+ mole fraction. Dashed line nonpreference isotherm, (b) In Ky plot to determine the equilibrium constant The dotted lines are extrapolations and the stars represent extrapolated points. 

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Exchange Calculated by Argensinger Method k n Argensinger method Rothmund- Kornfeld method... 

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