Evaluation of organic modification of montmorillonite with ionic and nonionic surfactants

This work aims at evaluating the organophilization of montmorillonite with two different types of surfactants: one ionic, containing C16-C18 di(alkyl ester) dimethyl ammonium chloride (EA) and one nonionic, containing ethoxylated tallow amine (ETA). Aqueous dispersion and semi-solid routes were compared in terms of functionalization efficiency by statistical analysis, and supercritical CO2 was performed as a complementary and comparative method. Besides, the effect of the washing process after functionalization was evaluated. X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) and contact angle were used to evaluate the intercalation of surfactants into montmorillonite and process yield. The d001-value was improved by both surfactants intercalation, and the conformations of the species inside the clay minerals were suggested. The final arrangement of the organic species into Mt was modified as a function of the concentration of surfactant added, and by the washing steps. Most process parameters evaluated showed significant effects on d001-value and process yield. The semi-solid method was confirmed as a good alternative route due to its efficiency and it could be an environmentally friendly option to be used. ETA-modified montmorillonites showed similar d001-values (around 4.0 nm) and higher thermal stability than EA-modified montmorillonite.