Preparation and characterization of zwitterionic surfactant-modified montmorillonites

Al13-pillared montmorillonite modified by cationic and zwitterionic surfactants: A comparative study

“…Being located in AlPMt, the loaded Z16 surfactant decomposed at a higher temperature as compared with the "free" (pure) compound (~334°C). With Z16-modified OMt and at low surfactant dosages (0.2-0.6 CEC), Zhu et al (2011) recorded a DTG peak near 390°C due to the decomposition of Z16 occupying cation exchange positions; that was, attached to negatively charged sites on interlayer surfaces by electrostatic attraction. When the surfactant dosage was increased, a new DTG peak appeared at~340°C which was assigned to the decomposition of surfactant molecules held by van der Waals forces and electrostatic interaction between the quaternary ammonium and sulfonate groups.…”

“…This finding indicated that Z16 either failed to penetrate the interlayers of AlPMt, or was loaded in the interlayer space of AlPMt in a configuration without causing interlayer expansion. Interestingly, Zhu et al (2011) reported that the basal spacings of montmorillonites, modified with different concentrations of cationic surfactants, were smaller than those of their counterparts with zwitterionic surfactants. It would, therefore, appear that the negatively charged sulfonate group in Z16 plays a key part in the intercalation of the zwitterionic surfactant into AlPMt.…”

“…Evidently, the cationic surfactant was more easily intercalated into AlPMt than the zwitterionic type. By comparison with AlPMt, calcium-montmorillonite (Ca-Mt) had a high propensity for intercalating zwitterionic surfactants over a wide dosage range from 0.2 to 4.0 CEC (Zhu et al, 2011). Thus, partial occupancy of the montmorillonite interlayers by Al 13 cations appeared to hinder interlayer entry of zwitterionic surfactants but had little influence on the intercalation of cationic surfactants.…”

“…1) is an example of a zwitterionic surfactant. Besides being highly water-soluble, biodegradable, and biologically safe, sulfobetaine can readily intercalate into the interlayer space of montmorillonite (Zhu et al, 2011).…”

Adsorption of phenol and Cu(II) onto cationic and zwitterionic surfactant modified montmorillonite in single and binary systems

“…Sulfobetaine containing both positively charged (quaternary ammonium) and negatively charged (sulfonate) groups is a type of zwitterionic surfactant. Besides being highly water-soluble, biodegradable and biologically safe, sulfobetaine can retain its zwitterionic character over a broad pH range and readily intercalate into the interlayer space of montmorillonite [19]. It might therefore be expected that this novel OMt, intercalated with zwitterionic surfactant, can simultaneously remove organic contaminants and heavy metals in one step.…”