Driving force for the hydration of the swelling clays: Case of montmorillonites saturated with alkaline-earth cations

摘要: Abstract Important structural modifications occur in swelling clays upon water adsorption. The multi-scale evolution of the clay structure is usually evidenced by various experimental techniques. However, driving force behind such phenomena still not thoroughly understood. It appears strongly dependent on nature interlayer cation. In case montmorillonites saturated with alkaline cations, it was inferred that compensating cation or layer surface could control hydration process and thus opening space, depending present study, emphasis put impact divalent alkaline-earth cations charge montmorillonites. Since no technique offers possibility directly determining contributions related to surfaces, an approach based combination electrostatic calculations immersion data developed here, as already validated cations. This methodology allows estimate energy for therefore shed a new light occurring Firstly, values obtained from Electronegativity Equalization Method vary 450 mJ m−2 Mg-montmorillonite 1100 mJ m−2 Ba-montmorillonite. Secondly, considering both can be attributed Mg-, Ca-, Sr-montmorillonites Ba-montmorillonites. These results explain differences behaviour adsorption function cation, thereby allowing macroscopic trends better knowledge processes homoionic may great importance natural samples where mixtures two types are also provides valuable information exchange clays.