Construction of Gemini composite based on TiO2 pillared montmorillonite for efficient oil-water separation

Owing to the changeable components of oil-water system and the inflexible limitation of available materials during oil-water separation, the treatment of oily wastewater with wide pH, large discharge and high COD value remains a great challenge. In this study, a simple strategy was used to construct Gemini composite based on TiO2 pillared montmorillonite. The resultant montmorillonite-based Gemini composite (QATMt-x) exhibited high surface area (116.54 m2 g-1), surface potential (18.8 mV at pH2), good acid and alkali resistance, amphiphilicmultifunctional surface, and defective layered structure and, as a result, delivered high capability (ED >= 96 %) and long cyclic life for oil-water separation. More significantly, detailed mechanism studies reveal that the crucial reasons of oil-water separation on microemulsion and aqueous containing organic contaminant are demulsification through electron capture of the grafted chitosan, and adsorption by lipophilic saturated alkanes, titanium hydrates, (metal) hydroxyl and amine group, respectively. Hence, QATMt-x is particularly suitable for efficient demulsification in acidic media (pH 2) and for the adsorption of ecotoxic organic substances (e.g., perfluorooctanoic acid, methyl blue). In short, construction of Gemini surfactants based on low-cost inorganic carriers would offer new strategies in exploring amphipathic dual-functional layered structures for simultaneously efficient separation of multisystem oil-water scenarios.