Mohsen Abbasi

Natural bentonite and zeolite powder were used to investigate their capability for oily wastewater treatment in equilibrium state by adsorption process. All experiments were carried out at ambient temperature. Initial concentration was varied between 200-800 ppm. Also, five isotherm models, including Langmuir, Freundlich, Temkin, Toth, and Sips were applied to describe equilibrium adsorption. The results showed the amount of loading was increased by increasing concentration. The powder bentonite had better performance in comparison to zeolite powder and maximum removal was determined 69.2% and 37.8% for bentonite and zeolite, respectively. It was found Freundlich isotherm model conformed to experiment equilibrium data more than the other isotherm for both adsorbent. Also, maximum Langmuir capacity was determined 30.88 and 24.54 mg/g for natural bentonite and zeolite, respectively. Langmuir isotherm had the worst prediction of oil loading onto adsorbent. Thus, oil adsorption onto bentonite and zeolite powder behavior is non-ideal, multilayer, and adsorption active sites are heterogeneous.