Abstract: The modified bentonite was prepared using bentonite modified with cetyltrimethyl ammonium bromide (CTAB).The structure of this modified bentonite was characterized by fourier transform infrared spectra (FTIR) and XRD.The effects of the dosage and pH value on the adsorption of Congo red from water were studied.The thermodynamics and kinetics of Congo red adsorption on the modified bentonite was stuied also.It is shown that the CTAB could be inserted into the interlayer of bentonite with the removal rate as high as 97.15% when the dosage is 4 g/L and pH is 4.The adsorption process of Congo red on the modified bentonite followed the pseudo-second order kinetic equation and the adsorption behavior fited with the Langmuir sorption isotherm equation.The results of thermodynamic analysis are:enthalpy (ΔH)< 0,Gibbs free energy (ΔG)<0,and entropy (ΔS)<0,which suggest that the sorption is an exothermic, spontaneous and decreasing entropy process.

Key words: CTAB;bentonite;Congo red;adsorption;kinetics;thermodynamics