Ultrasound-assisted preparation and characterization of anionic surfactant modified montmorillonites

Ca-montmorillonite was modified with sodium dodecyl sulfate (SDS) and sodium stearate (SSTA) in acidic medium using ultrasound. X-ray diffraction (XRD) analysis, elements analysis (EA), thermal analysis (TG-DTA) and Fourier transform infrared (FT-IR) spectroscopy indicated that the anionic surfactants were intercalated expanding the basal spacing to 3.87 nm (SDS/MMT) and 4.80 nm (SSTA/MMT), respectively. The dodecanesulfonate and stearic ions entered the interlayer space in the form of ion pairs with Na+. The sulfonate groups of SDS and the carboxyl groups of SSTA formed hydrogen bonds with water molecules in the interlayer space.

Research Highlights
► The intercalation reactions of anionic surfactants, SDS and SSTA, into montmorillonites (MMT) were found and studied.
► The anionic surfactants were intercalated expanding the basal spacing to 3.87 nm (SDS/MMT) and 4.80 nm (SSTA/MMT), respectively.
► The sulfonate groups of SDS and the carboxyl groups of SSTA formed hydrogen bonds with water molecules in the interlayer space.