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Adsorption of rhodamine B by acid activated carbon-kinetic and thermodynamic studies

S.Arivoli, M.Hema

A carbonaceous adsorbent prepared from an indigenous waste by acid treatmentwas tested for its efficiency in removing rhodamine B(RDB). 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 isothermmodelswere applied to the equilibrium data. The adsorption capacity (Qm) obtained from the Langmuir isotherm plotswere 68.29, 68.21, 70.05 and 70.48mg/g respectively at an initial pHof 7.0 at 30, 40, 50 and 600C. The temperature variation study showed that the Rhodamine B 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 Rhodamine B solutions. Almost 62% removal of Rhodamine B 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 Rhodamine B onMCC involves physisorption mechanism.