Effect of the intercalation conditions of a montmorillonite with octadecylamine

Intercalation of montmorillonite with octadecylamine under several conditions is reported. Octadecylamine was protonated in situ with HCl to obtain octadecylammonium cations. Water and water/ethanol mixtures were used as reaction medium, and the ratios amine/clay and HCl/amine were also varied. Intercalation was successful when the amine/clay ratio was in the range 1-3 mmol/g; optimal results were obtained for an amine/clay ratio of 2.0 mmol/g. For a given amine/clay ratio, the HCl/amine ratio also influences the intercalation. Basal spacings of the intercalated solids were between 13.4-36.7 Å. The amount of organic matter incorporated into the solids also varied widely; up to 40 wt% is fixed. Specific surface area is very low in all the intercalated solids because of the blockage of the clay porosity by the organic molecules. Co-intercalation of octadecylammonium and of the inorganic polycation [Al13O4(OH)24(H2O)12]7+ was also considered, giving rise to intercalated solids with basal spacings between 17 and 22 Å, also with a high fixation of organic matter.