Identification and Quantification of the Interaction Mechanisms Between the Cationic Surfactant HDTMA-Br and Montmorillonite

Abstract

Several detailed studies have been done on the characterization of organoclays and the type of structures developed when they interact with alkylammonium molecules. Few published contributions exist, however, on the distribution of surfactant within the organoclays and the mechanism by which they are intercalated. Also, although X-ray photoelectron spectroscopy (XPS) is a suitable technique for the study of the surface characteristics of organoclays, very few such XPS studies have been carried out. With the aim of contributing to a better understanding of the intercalation process, a series of organoclays was synthesized using a montmorillonite and the cationic surfactant hexadecyltrimethylammonium bromide (HDTMABr), with an increasing surfactant load of between 0.2 and 4.0 times the cation exchange capacity of the starting clay. By means of XPS, zeta potential, and thermal analysis techniques, distinguishing the strongly interacting fraction from the weakly interacting fraction of the adsorbed surfactant molecules was possible. Adsorption isotherms of each of these processes were constructed and then adjusted using the Langmuir and Dubinin-Radusquevich adsorption models. Three types of interaction between the surfactant and the clay were identified and described qualitatively and quantitatively. Two of these interactions, strong and weak, involved the hexadecyltrimethylammonium cation (HDTMA+). The third was a weak interaction involving the ion pair HDTMA+Br−. The results of this study may be useful for the comprehensive design of organoclays with specific physicochemical properties according to the application for which they are destined.

Effect of surfactant molecular structure on perchlorate removal by various organo-montmorillonites

“…Also the molar ratios of Al/Si, Cl/Si, N I /Si, and N total /Si in the organo-Mt before perchlorate adsorption were calculated from the high-resolution XPS results as summarized in Table 3. The Al/Si ratio significantly decreased in C18-BM/Mt and 2C18-DM/Mt after modification, because some Al-O(H) sheets were out of the detection by the incorporation of bulky C18-BM and 2C18-DM on the external surface Naranjo et al, 2013). In addition, there is a trend that higher surface molar ratios of N C /Si and Cl/Si were obtained for composites modified with longer alkyl chains.…”

“…TG-DTA curves of organo-Mt are associated with the distribution (either in the interlayer space or on the external surface) and the existing form (with or without counter ions) of loaded surfactant in composites (Yariv, 2004;Naranjo et al, 2013). Ionized surfactant located in the interlayer is more difficult to decompose than the counter ionaccompanying form on the external surface, because the former is protected by the Mt layers and anchored to the Mt surface by strong electrostatic force rather than weak hydrophobic interaction (Xi et al, 2005;Zhu et al, 2012).…”

“…of the ionized surfactant (N I ) (Naranjo et al, 2013). Also the molar ratios of Al/Si, Cl/Si, N I /Si, and N total /Si in the organo-Mt before perchlorate adsorption were calculated from the high-resolution XPS results as summarized in Table 3.…”

Surface and textural characterization of TiO2 pillared organoclays

“…The existence of interference of the quaternary amine (HDTA) in the determination of the CEC is not considered. This assumption is based on the fact that the surfactant adsorption in the interlayer space is produced by a strong adsorption mechanism that involves the formation of inner-sphere and/or charge-transfer with clay layers [21]. The CEC percentage concerning the CEC of the starting clay was calculated in each case.…”

Immobilizing and Removal of Cadmium and Rhodamine B from an Aqueous System by Converting Solid Waste from Poland; Studies of Equilibrium and Kinetic Sorption

“…The bands could indicate that the -OH groups bound to aliphatic compounds correspond, respectively, to symmetric and asymmetric stretching vibrations of the methylene group -CH 2 - [17]. The band at 1630 cm -1 related to bending vibrations of water molecules.…”