Gemini surfactant, 1,1'-(butane-1,4-diyl)-bis(3-(tetradecyloxycarbonyl)pyridinium) dibromide (designated as N-G), and the corresponding monomer, 1-ethyl-3-(tetradecyloxycarbonyl)pyridinium bromide (N-S), were prepared and utilized to modify sodium bentonite (Na-Bt). The surfactant modified bentonites (N-G-Bt for the gemini modified bentonite and N-S-Bt for the monomer modified one) were then used for methyl orange (MO) removal from the wastewater. The results indicated that the gemini surfactant N-G was more effective than the monomer N-S at expanding the interlayer space of Na-Bt and in removing MO from wastewater. The maximum basal spacing of N-G-Bt (4.02 nm) was almost twice as that of N-S-Bt (2.63 nm). MO removal efficiency was 9.68% for 4.0N(S)-Bt and 99.88% for 4.0N(G)-Bt at a dosage of 0.06 g, respectively. N-S easily intercalated into the interlayer of Na-Bt, however more N-G mainly stayed on the solid surface owing to its bigger head. The adsorption of both N-G and N-S on Na-Bt obeyed the pseudo-second-order kinetic model and Langmuir isotherms. The solid-state UV-vis spectrometry evidenced the formed complex of N-G/N-S with MO on Na-Bt, and the stronger interaction of N-G-Bt with MO. (C) 2013 Elsevier B.V. All rights reserved.