Original Articles: 2010 Vol: 2 Issue: 5
Adsorption dynamics of methylene blue by acid activated carbon
Abstract
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.