Adsorption of Methyl Orange on Corncob Activated Carbon: Kinetic, Equilibrium, and Thermodynamic Studies

H3PO4 activated corncob carbon was used for removal of methyl orange. Characterization of the prepared carbon showed that it has many pores with a specific surface area equal to 714 m2 g-1. During this study, the concentration of methyl orange was monitored using a UV-visible spectrophotometer. The kinetic study of the adsorption of methyl orange on activated carbon was performed and the adsorption rate was found to be consistent with pseudo-second order kinetics with 240 min as the equilibrium time. The equilibrium adsorption revealed that the experimental data better fit the Langmuir isotherm model for methyl orange removal. It is noted that for optimal removal of 10 mg L-1 methyl orange in a 25 mL volume, 0.3 g of activated carbon and a pH equal to 2.04 are required. The maximum monolayer adsorption capacity for methyl orange removal was found to be 107.527 mg g-1. Analysis of thermodynamic parameters showed that the adsorption process of methyl orange on activated carbon is physisorption, spontaneous and endothermic.