Acid-Base Properties of Cation-Exchanged Montmorillonites

3 Acid-Base Properties of Cation-Exchanged Montmorillonites 

The acid-base properties of calcium-, copper-, zinc-, and manganese-montmoril-lonites produced from calcium-montmorillonite were studied by potentiometric titration (Nagy and Konya 2004 Nagy et al. 2004). The neutralization reactions of Cu, Zn, and Mn ions can be described by Equations 2.6-2.8  

The stability constants of neutralization reactions can be calculated from the  

CaX2 + Cu2+ = CuX2 + Ca2+, 1Z Ca.Cu aCuX2 aca2+ aCaX2 aCu2+ r CaX2 (2.16) 

As a conclusion, the parameters of the protonation/deprotonation of edge sites, namely, the number of edge sites and intrinsic stability constants, can be estimated if the parameters of the cation-layer charge interactions (number of layer charge [cation-exchange capacity] and the specific surface area) are known from independent experimental data and they can be included in the equation describing the system as constant values. 

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