Sohrab A. Ghorbanian - School of Chemical Engineering, College of Engineering, University of Tehran, Enghelab Street, Tehran, Iran,
Nafiseh Bagheri - Department of Chemical Engineering, North Branch, Islamic Azad University, Tehran, Iran
Amir Khakpay - School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran

In industrial processes, granular activated carbon is generally used to recover and remove pollutants from waste water. In this paper, the equilibrium adsorption of benzoic acid on granular activated carbon has been investigated. Experiments were carried out by two sizes of activated carbon. The equilibrium data were analyzed with Langmuir, Freundlich, Radke–Prausnitz, Redlich-Peterson, Sips, and Freundlich- Jovanovic isotherm models using ordinary least square method. The results show that the adsorption process was more effectively described by Freundlich-Jovanovic isotherm model based on the values of the least square parameter, Durbin- Watson Test, and mean relative percent error. Furthermore, the results show that benzoic acid has been adsorbed more on the adsorbent with smaller size

Adsorption, isotherm curves, activated carbon,modeling, statistical analysis