The adsorption behavior of anionic dye onto bentonite materials

Surfactant-modified bentonite (GZ-O-Ben) was prepared by intercalating cetyltrimethyl ammonium bromide into the natural bentonite from Gaozhou, China. GZ-O-Ben was characterized by X-ray diffraction, N-2 adsorption and Fourier transform infrared spectroscopy. Methyl orange was selected as the model anionic dye. The adsorption isotherm of methyl orange onto GZ-O-Ben can be well described by Langmuir model. The maximal adsorption equilibrium constant of methyl orange onto GZ-O-Ben was achieved at pH 5.0. The adsorption kinetics of methyl orange could be well described by the pseudo-second-order kinetic model. Calculated with the pseudo-second-order kinetic model, the adsorption kinetic constants of methyl orange onto GZ-O-Ben increased with the increase of adsorbent dosage.