Near-infrared and mid-infrared investigations of Na-dodecylbenzenesulfate intercalated into hydrocalumite chloride (CaAl-LDH-Cl).

Hydrocalumite (CaAl-LDH-Cl) belongs to layered double hydroxides (LDHs). The intercalation of Na-dodecylbenzenesulfate (SDBS) into CaAl-LDH-Cl has been investigated by X-ray diffraction (XRD), mid-infrared (MIR) spectroscopy and near-infrared (NIR) spectroscopy. The mid-infrared spectra indicated that SDBS could be intercalated into CaAl-LDH-Cl, with the same lattice structure to that of CaAl-LDH-Cl, and the interlayer distance of resultant product was expanded to 2.78 nm as confirmed by XRD. The near-infrared spectra (9200-4000 cm(-1)) showed that a special spectral range from 6200 to 5600 cm(-1) and prominent bands of CaAl-LDH-Cl intercalated with SDBS around 8300 cm(-1). This band was assigned to the second overtone of the first fundamental of C-H stretching vibrations of SDBS, and can be used to determinate the result of CaAl-LDH-Cl modified by anionic surfactants. The bands of water stretching vibrations and -OH groups shifted to higher wavenumbers when CaAl-LDH-Cl was intercalated by SDBS, and their intensity of MIR and NIR spectra became lower in intensity.