Adsorption potential of maize cob carbon for 2,4-dichlorophenol removal from aqueous solutions: Equilibrium, kinetics and thermodynamics modeling

The present study deals with the adsorption potential of thermally activated carbon developed from maize cob for the removal of 2,4-dichlorophenol (2,4-DCP) from aqueous solutions. Studies were conducted to delineate the effects of contact time, 2,4-DCP initial concentration, pH and temperature. The kinetics of 4-DCP adsorption from a solution onto an adsorbent was explored experimentally. Non-linear form of pseudo-second-order model showed a better fit with good correlation co-efficient. Bangham's and intraparticle diffusion model were also used. Non-linear form of Langmuir isotherm model was applied and the data correlate well and the maximum adsorption capacity was found to be 17.94 mg/g for the particle size of 250-500 mu m. Acidic pH was favorable for the adsorption of 2,4-DCP. Studies on pH effect and desorption showed that chemisorption mechanism was involved in the adsorption process. Thermodynamic study showed that adsorption of 2,4-DCP on maize cob carbon is more favored. The change in entropy (AS,) and heat of adsorption (Delta H degrees) of maize cob carbon were estimated as 26.91 J/(K mol) and 6.78 kJ/mol, respectively. (C) 2008 Elsevier B.V. All rights reserved.