Adsorption of dodecyl- and octadecyltrimethylammonium ions on a smectite and synthetic micas

The influence of alkyl chain length on surfactant distribution within organo-montmorillonites and their thermal stability

“…This implies that some intercalated surfactants are evaporated in this temperature region. As reported in the literature [30], there were two kinds of surfactants intercalated into the clay interlayer spaces: when the amount of the intercalated surfactant is less than the clay's CEC, the surfactants mainly enter into clay interlayer spaces as cations via cation exchange; when the amount of the loaded surfactant is more than clay's CEC, surfactants can enter into clay interlayer spaces as both cations and molecules (ionic pairs) [30] and surfactant molecules also can occupy the interparticle pores within ''house-of-cards'' structure [32]. It is no doubt that that the surfactants loaded in the interparticle pores will be evaporated around the evaporation temperature of the neat surfactant.…”

“…As reported in the literature [14,29], more than 1 9 CEC surfactant was loaded when the maximum basal spacing reached. The surfactant can be loaded by two different styles, i.e., surfactant cations and surfactant molecules (ionic pairs) [30], and they can occupy both the interlayer spaces of clay minerals and the interparticle pores within ''house-of-cards'' structure [6,31,32]. In their thermal stability analyses, the mass loss around the evaporation temperature of the neat surfactant was attributed to the surfactant loaded in the interparticle pores within the ''house-of-cards'' structure while the mass losses at higher temperatures (except the dehydroxylation) to evaporation/ decomposition of the intercalated surfactants [13,22].…”

Quaternary ammonium compounds in soil: implications for antibiotic resistance development

“…In industrial organoclay production, where large concentrations of QAC are employed to modify smectite surfaces, expansion of interlayer distances of up to 2.7 nm was determined (de Paiva et al 2008), and the arrangement of ATMAC and DADMAC in mono-, biand pseudo-triple layers within expandable clays is also known (Jasmund and Lagaly 1993; Ruiz-Hitzky and Van Meerbeek 2006). In the context of remediation of soils contaminated with hydrophobic organic compounds, several studies reported expansion of the d001 basal spacing of smectites by QACs up to 2.1 nm (Koh and Dixon 2001;Klapyta et al 2001;Zhu et al 2003;Martin-Sanchez et al 2012): Therefore, it seems likely that intercalation of QAACs into the interlayers of clay minerals is one main endpoint of QAAC sequestration in soils, probably contributing to the socalled pool of non-extractable residues which to our knowledge has not yet been assessed for these compounds.…”

Molecular Simulation of the Interlayer Structure and the Mobility of Alkyl Chains in HDTMA+/Montmorillonite Hybrids

“…So far, X-ray diffraction (XRD) is the most widely used technique to determine the structure of organoclays. [8][9][10][11][12] On the basis of the measured basal spacings and the length of the alkyl chains, various arrangement models have been proposed for the intercalated surfactants, including lateral-monolayer, lateral-bilayer, pseudo-trilayer, paraffin-monolayer, and paraffinbilayer. 8 These idealized models are based on the assumption that the intercalated surfactants adopted all-trans conformation after intercalation.…”