The mesoporous carbon CMK-3 adsorbent was prepared, characterized, and used for the removal of
anionic methyl orange dye from aqueous solution. Adsorption experiments were carried out as batch
studies at different contact time, pH, initial dye concentration, and salt concentration. The dye adsorption
equilibrium was rapidly attained after 60 min of contact time. Removal of dye in acidic solutions was
better than in basic solutions. The adsorption of dye increased with increasing initial dye concentration
and salt concentration. The equilibrium data were analyzed by the Langmuir and Freundlich models,
which revealed that Langmuir model was more suitable to describe the methyl orange adsorption than
Freundlich model. Experimental data were analyzed using pseudo-first-order and pseudo-second-order
kinetic models. It was found that kinetics followed a pseudo-second-order equation. Thermodynamic
study showed that the adsorption was a spontaneous and exothermic process.