Abstract
A comparative study on the intercalation of the hexadecyltrimethylammonium (C16TMA) cations into two montmorillonites with different cation exchange capacity (CEC) values, is reported. The effect of selected counterions (Br-, Cl- and OH-) on the adsorption of C16TMA was investigated. The aim of this study is to gain further insight into the influence of the type of surfactant solutions and the physicochemical properties of raw clays on their intercalation behaviors. The intercalated amounts depended on the CEC values of the starting clays and the type of C16TMA solutions. The content of surfactants was higher in the raw clay with higher CEC, and followed the trend C16TMABr>C16TMACl>C16TMAOH. The expansion of the basal distance in the range of 1.8nm to 3.7 nm, was related to the starting raw clay and to the starting concentrations of bromide and chloride surfactant solutions. However, the interlayer spacing was almost independent of the starting raw clay-and the concentrations of C16TMA hydroxide solution, related to a difficult swelling behavior of clay sheets in basic solutions.
