Study on Structure Characteristics of Organic Hectorite Hydrothermally Synthesized in Reaction Medium with the Presence of Surfactants

Using lithium fluoride,magnesium chloride,water glass and ammonium hydroxide as the main reactants,the layered organic hectorite-type solids were synthesized hydrothermally in the reaction medium in the presence of surfactant.Cationic cetyltrimethyl ammonium bromide(CTAB) and neutral dodecyl amine(DDA)—two kinds of surfactants at different ratios were used in the hydrothermal process.The structures of the synthesized samples were characterized respectivery by Fourier transform infrared spectroscopy(FT-IR),power X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),thermal gravimetric analysis and differential thermal analysis(TGA/DTA) and N2 adsorption-desorption isotherms.The results show that,with the addition of surfactant of either CTAB,DDA or CTAB+DDA in the hydrothermal reaction medium,the layered hectorite-type solid could be obtain at all times.When only CTAB was added to the reaction medium,the moiety of cationic CTA+ could partly intercalate into the interlayer of the hectorite-type solids.On the contrary,adding neutral DDA has no intercalation effect.In the presence of two mixed surfactants of CTAB and DDA,the DDA could hinder the intercalation of CTAB and reduce the amount of CTAB intercalating in the interlayer.Moreover,CTAB has a great influence on the morphology and pore size distribution of the synthesized compound,and it causes the compound to have a swelling layered structure.