Although there have been some publications on the effects Calorimetry, static technique, and X-ray diffraction ( XRD ) of type of clay, alkyl chain length of cationic surfactant, and analysis were employed to study the adsorption of cetyltrimethtemperature on the adsorption behavior (11-13), most of ylammonium bromide ( CTAB ) and dodecyltrimethylammonthem were restricted to mono-and bivalent cation-exchanged ium bromide ( DTAB ) on Fe -montmorillonite and Na -montclays. With the increasing practical and theoretical interests, morillonite suspensions. The results show that the process of the interactions of trivalent cations, such as Fe 3/ and Al 3/ , adsorption is exothermic and that the type of clay and the alkyl with clay suspensions are receiving more attention (14-17).
chain length of surfactant affect the amount of adsorption and
However, studies on the adsorption of alkyltrimethylammonthe enthalpy of adsorption significantly but that the effect of ium bromide surfactants on Fe 3/ -exchanged montmorillontemperature is very limited in the temperature range studied.
The magnitudes of adsorption amount and adsorption enthalpy ite suspensions are scarce, possibly because of the complexfollow the order Na-montmorillonite ΓΊ Fe-montmorillonite, ity of interaction mechanism between Fe 3/ and the clay sus-CTAB ΓΊ DTAB. The basal spacings determined by X-ray powpension and the limited experimental techniques for studying der diffraction indicate that the CTAB adsorbed between the suspensions. clay interlayers in a bilayer arrangement, while the DTAB Static techniques (i.e. adsorption isotherm measurements) formed bilayers or monolayers at saturation adsorption between and spectroscopic methods (such as X-ray diffraction and the Na-montmorillonite and Fe-montmorillonite interlayers, reneutron scattering) are routine techniques for investigating spectively. The adsorption mechanism is also discussed on the adsorption behavior and adsorption mechanisms. For exambasis of the experimental data. α§ 1998 Academic Press ple, De Β΄ka Β΄ny et al. (18-21) studied the adsorption isotherms