In situ synthesis of surfactant/silane-modified hydrotalcites

In this study, anionic surfactant and silane-modified hydrotalcites were synthesized through a soft chemical in situ method. The resulting materials were characterized using X-ray diffraction (XRD), high-resolution thermogravimetric analysis (HRTG), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and N2 adsorption–desorption. The Mg–Al hydrotalcite (LDH) and the only surfactant-modified hydrotalcite (LDH-2) display similar XRD patterns while both surfactant and silane-modified hydrotalcite (LDH-3) show two distinct series of reflections, corresponding to hydrotalcite and smectite-like materials, respectively. The smectite-like materials show a series of regular (001) reflections with d001=12.58 Åd001=12.58 Å. Further supporting evidence was obtained from FTIR and TG, for example, the vibration at 1198 cm−1 corresponds to SiOSi-stretching mode and the mass loss at ca. 861 °C to dehydroxylation. In LDH-2, the loaded surfactants are located in both the interlayer space and the interparticle pores with a “house of cards” structure as supported by FTIR, TG, and N2 adsorption–desorption isotherms. Both electron microscopy (SEM and TEM) micrographs and N2 adsorption–desorption isotherms show that in situ modification with surfactant and silane has a significant influence on the morphology and porous parameters of the resulting hydrotalcite materials.

The XRD pattern of the both surfactant- and silane-modified hydrotalcite (LDH-3) shows a coexistence of two phases, hydrotalcite and smectite-like layered materials.Figure optionsDownload as PowerPoint slide