Acid-base properties of 2:1 clays: The role of electrostatics

2010

International audience; We present a theoretical and experimental investigation of the titratable charge of 2:1 clays with various structural charge ('b): pyrophyllite ('b = 0 e. nm(2), montmorillonite ('b = -0.7 e. nm(2) and illite ('b = -1.2 e. nm(2). The calculations were carried out using a Monte Carlo method in the Grand Canonical ensemble and in the framework of the primitive model. The clay particle was modeled as a hexagonal platelet, with an ‘ideal' crystal structure. The only fitting parameters used are the intrinsic equilibrium constants for the protonation/deprotonation reactions of the broken-bond sites on the lateral faces. Simulations are found to give a satisfactory descript…