SOLID-STATE SYNTHESIS AND PHYSICO-CHEMICAL CHARACTERIZATION OF MODIFIED SMECTITES USING NATURAL CLAYS FROM BURKINA FASO

Solid-state intercalation was applied to prepare organo-smectites using cationic surfactants and natural clays containing smectite at various surfactant/smectite ratios. The surfactants enter the interlayers of smectites causing a swelling of the clays. The used clays were collected in Sietougou and Diabari villages located in the eastern part of Burkina Faso. The solid-state intercalation was successful for all four surfactants applied, n-dodecyltrimethylammonium bromide, (n-C12H25(CH3)(3)NBr), n-tetradecyltrimethylammonium bromide, (n-C14H29(CH3)(3)NBr), n-hexadecyltrimethylammonium bromide (n-C16H33(CH3)(3)NBr) and di-n-dodecyldimethylammonium bromide ((n-C12H25)(2)(CH3)(2)NBr) at different levels of the cation exchange capacity (CEC). The synthesized organo-smectites were characterized regarding relative density, structural and textural properties. XRPD data showed a systematic increase of the basal spacing of the unit cell of the smectite up to >38 angstrom at 2.0-CEC loading of the surfactant. This increase indicates that the surfactants penetrated into the smectite interlayers with the surfactants being arranged parallel to the layers at low concentrations and almost perpendicular at high ones. FTIR spectra of the organo-smectites showed a decrease in the intensities of the water bands at around 1630 cm(-1) and 3400 cm(-1), and new specific bands close to 2920 cm(-1) and 2850 cm(-1) were assigned to the asymmetric and symmetric stretching of CH2 groups of the surfactants, respectively.

Automated summary

Solid-state intercalation was successfully used to prepare organo-smectites with various cationic surfactants and natural clays. XRPD data showed an increase in the basal spacing of the unit cell of the smectite with the surfactant loading, indicating the penetration of surfactants into the interlayers. FTIR spectra demonstrated changes in the intensity of water bands and the appearance of new bands related to the surfactants' CH2 groups.