In situ synthesis of surfactant/silane-modified hydrotalcites

Abstract

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 N 2 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 d 001 = 12.58 Å . Further supporting evidence was obtained from FTIR and TG, for example, the vibration at 1198 cm −1 corresponds to Si O Si-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 N 2 adsorption–desorption isotherms. Both electron microscopy (SEM and TEM) micrographs and N 2 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.