A Comparison of New Gemini Surfactant Modified Clay with its Monomer Modified One: Characterization and Application in Methyl Orange Removal

摘要

New gemini surfactant, glycol bis-N-tetradecyl nicotinate dibromide (designated E_G), and the corresponding monomer, methyl N-tetradecyl nicotinate bromide (E_s), were synthesized and utilized to modify sodium bentonite (Na-Bt). E_G-Bt and E_s-Bt, the surfactant modified bentonites, were then used for methyl orange (MO) removal from the dye solution. E_G was more effective than E_s at expanding the interlayer space of Na-Bt. The adsorption of E_G, E_s and MO obeyed well the pseudo-second-order kinetic model and Langmuir isotherms on Na-Bt or on the modified bentonite. However, the adsorption of E_G was more spontaneous than that of E_s, and E_G replaced more small particles, such as Na~+ and water, than E_s did during the adsorption on Na-Bt. The elevated temperature impairs the adsorption of the surfactants, but enhances that of MO. MO absorbed more easily on E_G-Bt than on E_s-Bt, When the dosage of the surfactants used goes beyond a certain amount, the uptake of MO by E_G-Bt/E_s-Bt decreases slowly owing to desorptibn of the surfactants. E_G and E_s formed a complex with MO on the modified bentonite as evidenced by UV—vis spectra, and E_G exhibited the stronger interaction with MO.