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E-Journal of Chemistry
Volume 9 (2012), Issue 4, Pages 2575-2588

Thermodynamic and Isotherm Analysis on the Removal of Malachite Green Dye Using Thespesia Populnea Bark

1Mount Zion College of Engineering and Technology, Pudukkottai Tamilnadu, India
2PRIST University Vallam, Thanjore (District), Tamilnadu, India
3Department of Chemistry, Thiru-V-Ka, Government Arts College, Thiruvarur, India

Received 9 August 2011; Accepted 22 January 2012

Copyright © 2012 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Activated carbon was synthesized from Thespesia Populnea Bark, a low cost material, by sulphuric acid activation; it was tested for its ability to eliminate malachite green in aqueous solution. The parameters studied included contact time, initial dye concentration, carbon dose, pH and temperature. The adsorption followed first order rate equation. In addition, it was found that the adsorption process was described by Freundlich and Langmuir isotherm models. Those models were applied to the equilibrium data. The absorption capacities (Qm) obtained from the Langmuir isotherm plots were 349.20, 365.43, 476.44, and 389.96 mg/g at 30°, 40°, 50°, and 60°C, respectively, at an initial pH 6.0. The temperature variation study showed that the malachite green dye absorption was endothermic and spontaneous with increased randomness at the solid solution interface. The thermodynamic parameters like ∆H°, ∆S°, and ∆G° were calculated from the slope and intercept of the linear plots.