Hooshyar Moghim Aliabadi - MESc, Fouman Faculty of Engineering, College of Engineering, University of Tehran,
Elham Saberikhah - MSc, Fouman Faculty of Engineering, College of Engineering, University of Tehran,
Azadeh Ebrahimian Pirbazari - Assistant Professor, Fouman Faculty of Engineering, College of Engineering, University of Tehran,
Reza Khakpour - MESc student, Caspian Faculty of Engineering, College of Engineering, University of Tehran

The use of aminopropyltriethoxysilane (APTES) modified wheat straw (WS) and NaOH-modified wheat straw (NMWS) for the removal of methyl orange (MO) from aqueous solutions was studied in details. The equilibrium data were analyzed by Langmuir, Freundlich, Temkin, Sips and Redlich-Peterson isotherm models and pseudo-first order and pseudo-second order kinetic models. The experimental results demonstrated that MO can be effectively removed from aqueous solution by both the adsorbent and the adsorption capacity of the APTES-NMWS was found to be higher than the APTES-WS. Various thermodynamic parameters, such asG°,H°,S° and Ea, have been calculated. The findings of this investigation suggested that physical sorption plays a role in controlling the sorption rate

Wheat straw, Methyl orange, aminopropyltriethoxysilane, Isotherms, Kinetics