Structural, thermal, morphological and surface charge properties of dodecyltrimethylammonium-smectite composites

•DDTMA cations intercalated into bentonite layers as lateral monolayer and lateral bilayer arrangements.•The entrance of the organic cations into the interlamellar space resulted in mesopore structures.•Electrophoretic mobility values and morphology of raw smectite are changed by the intercalation of the DDTMA cations.•The intercalation of DDTMA cations converted the hydrophilic smectite particles into hydrophobic organoclays.

The present investigation was undertaken to obtain information about the structural, thermal, morphological, surface charge and textural properties of the synthesized dodecyltrimethylammonium-smectite composites at various surfactant concentrations by means of powder X-ray diffraction, attenuated total reflection Fourier transform infrared, thermal analyses, scanning electron microscopy, electrophoretic mobility and surface area measurement techniques. The basal spacing values of organo-smectites varied between 13.55 and 17.00 Å that point out the successful intercalation of the surfactant cations into smectite layers with different molecular arrangements either lateral monolayer or lateral bilayer. Intercalation of surfactant cations led to appreciable decreases in the intensities of the bands at 3402 and 1635 cm−1 which originate from OH stretching and bending vibration of sorbed water molecules, respectively. Thermal analysis data showed that all organo-smectites had lower adsorbed water losses than raw and sodium-smectite and the removal of surfactant species occurred in the temperature range of 130–720 °C. The specific surface areas, pore volumes and micropore surface areas of organo-smectites decreased while the average pore width of these species increased with respect to that of raw smectite. The surfactant cations located in the interlayer spaces caused significant alterations in electrophoretic mobility values and morphology of raw smectite.