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.

Graphical abstract.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Hydrocalumites (Ca/Al-LDH) were synthesized and characterized. ► Methyl orange and acidic scralet GR modified the Ca/Al-LDH-Cl. ► Materials and surfaces were characterized by XRD, FT-IR and SEM, to verify the reaction process for methyl orange and acidic scarlet GR with Ca/Al-LDH-Cl. ► This work has shown that methyl orange was intercalated with Ca/Al-LDH-Cl and acidic scralet GR was adsorbed onto Ca/Al-LDH-Cl.