Adsorption dynamics of methylene blue by acid activated carbon

A carbonaceous adsorbent prepared from an indigenous waste by acid treatment was tested for its efficiency in removing Methylene blue. The parameters studied include agitation time, initial dye concentration, carbon dose, pH and temperature. The adsorption followed first order reaction equation and the rate is mainly controlled by intra-particle diffusion. Freundlich and Langmuir isotherm models were applied to the equilibrium data. The adsorption capacity (Qm) obtained from the Langmuir isotherm plots were 60.61, 59.95, 62.11 and 62.50 mg/g respectively at an initial pH of 7.0 at 30, 40, 50 and 600C. The temperature variation study showed that the Methylene blue adsorption is endothermic and spontaneous with increased randomness at the solid solution interface. Significant effect on adsorption was observed on varying the pH of the Methylene blue solutions. Almost 68% removal of Methylene blue was observed at 600C. The Langmuir and Freundlich isotherms obtained, positive
H0 value, pH dependent results and desorption of dye in mineral acid suggest that the adsorption of Methylene blue on MCC involves physisorption mechanism.