Nature of flocculation and tactoid formation in montmorillonite: the role of pH

作者:Segad M*; Akesson T; Cabane B; Jonsson Bo
来源:Physical Chemistry Chemical Physics, 2015, 17(44): 29608-29615.
DOI:10.1039/c5cp04007h

摘要

The dissolution and swelling properties of montmorillonite at different pH have been studied, using small angle X-ray scattering (SAXS), imaging and osmotic stress methods combined with Monte Carlo simulations. The acidity of montmorillonite dispersions has been varied as well as the counterions to the net negatively charged platelets. At low pH, Na montmorillonite dissolves and among other species Al3+ is released, hydrated, polymerized and then it replaces the counterions in the clay. This dramatically changes the microstructure of Na montmorillonite, which instead of having fully exfoliated platelets, turns into a structure of aggregated platelets, so-called tactoids. Montmorillonite dispersion still has a significant extra-lamellar swelling among the tactoids due to the presence of very small nanoplatelets.

  • 出版日期2015