Abstract:HDTMA+_pillared montmorillonites with surfactant arrangements of lateral-monolayer, lateral-bilayer and paraffin_bilayer, respectively, were prepared at different concentrations (0.5～2.5 CEC) of hexadecyltrimethylammonium bromide (HDTMAB). The sorption properties of the resultant organoclays were tested using p-nitrophenol as a model pollutant. The sorption efficiency of the organoclays increases with the increase of the solution pH, depending on the ionization extent of p-nitrophenol, whereas the sorption efficiency decreases with the increase of solution temperature, suggesting that the sorption reaction is exothermic. Generally, the sorption efficiency of organoclays increases with the increase of the surfactant packing density within montmorillonite interlayer, i.e., in the order of lateral-monolayer, lateral-bilayer and paraffin-bilayer.The isotherms for Na-montmorillonite, organoclays with lateral-monolayer and lateral-bilayer arrangements display S-type, implying that p-nitrophenol is mainly adsorbed on clay surfaces. For organoclays with paraffin_bilayer arrangement of the confined surfactants, their isotherms belong to Linear-type, demonstrating that p-nitrophenol enters the clay interlayer.
