Effects of variables on the dispersion of cationic–anionic organomontmorillonites and characteristics of Pickering emulsion

Abstract

In this study, montmorillonites modified with different amounts of cationic and anionic surfactants by variable steps were used as research objects; physicochemical properties, dispersion of cationic–anionic organomontmorillonites and characteristics of Pickering emulsion were further investigated. XRD diffraction studies of organomontmorillonites showed that basal spacings of organomontmorillonites increased first and then dropped with the increasing amount of cationic surfactants used in the process of modification. Contact angles and swell indices showed that organic matter in the interlayer of organomontmorillonites had a more profound effect than the surface polarity on the dispersion of organomontmorillonites. The micro-macro morphology, thixotropy and volume of emulsion of the Pickering emulsion at elevated temperatures were further tested. The results illustrated that organomontmorillonites modified by three steps with a certain range of surfactants, and surface coated by cationic surfactants were weakly flocculated and had uniform dispersion in a 90 : 10 oil–water ratio Pickering emulsion. The resulting emulsion had preferable stability and thixotropy. Cationic–anionic organomontmorillonites can be widely applied in the drilling industry and cosmetic industry as stable and cost-effective lipophilic colloid.