Adsorption Characteristics of Methylene Blue on Bentonite of Gansu Pingliang

An anion surfactant modified bentonite (SDS-Bt) was synthesized and characterized in order to study the adsorption behavior and the removal of Methylene Blue (MB) dye from aqueous solutions. The adsorption properties, kinetics and thermodynamics mechanism of MB on Bt and SDS-Bt were discussed in combination with the results of experiments. Adsorption data were analyzed according to Freundlich, Langmuir, Tempkin and Dubinin-Radushkevich adsorption models. Tthe results indicate that adsorption behavior of MB on Bt and SDS-Bt at experimental temperature range are all fitted Langmuir isotherms. The comparison of natural Bt and SDS-Bt show that both adsorbent could be considered as a potential sorbets for dye in aqueous solutions and SDS-Bt was the superior capacity. The kinetic values and thermodynamic parameters show that the dye adsorptions on both samples are all exothermic and spontaneous process. The adsorption process followed pseudo-second-order kinetics, mainly governed by the external mass transport with the activated energy of 9.76 kJ·mol^-1 and 5.77 kJ·mol^-1 for Bt and SDS-Bt respectively.