Gemini surfactant modified organo-clays for removal of organic pollutants from water: A review

Abstract

Novel organo-clays functionalized with gemini surfactants are one of the most prevalent adsorbents covering a vast range of organic pollutants. The adsorption performances, mechanisms and regenerabilities of organo-clays are closely associated with their interlayer structure, resulting from variations of modifier and/or the precursor. To this end, a comprehensive view of organo-clay adsorbents is described from two angles: preparation and adsorption. The synthetic routes of gemini surfactants (abbr. geminis) tuning the structure and morphology of organo-clays have been summarized, with the geminis examining on different layer charged precursors (vermiculite, montmorillonite and silica nanosheets with the layer charge decreasing). A systematic summarization, comparison and future prospection about the fate of novel organo-clays is achieved, including functionalization by gemini surfactants varying in alkyl chains, spacers, head groups and functional groups, adsorption and desorption towards specific pollutants, and novel characterization methods. The adsorption isotherms, kinetics, thermodynamics as well as additional interactions are compared and overviewed significantly. Furthermore, the limitations, differences and directions of organo-clay adsorbents are discussed.