Removal of Resorcinol from Aqueous Solution by Activated Carbon: Isotherms, Thermodynamics and Kinetics
Omer El-Amin Ahmed Adam *
Department of Chemistry, Faculty of Science and Arts, Al Baha University, Baljurashi 65635, P.O.Box 1988, Albaha, Saudi Arabia
*Author to whom correspondence should be addressed.
Abstract
The adsorption of resorcinol from aqueous solutions onto activated carbon was studied. The specific surface area and point of zero charge of activated carbon were determined. Adsorption experiments were carried out in a batch process and various experimental parameters such as agitation time, initial resorcinol concentration, adsorbent dose, pH and temperature were studied.
The equilibrium sorption data were fitted into Langmuir, Freundlich, Tempkin and Dubinin–Radushkevich (DR) isotherms. The Langmuir isotherm model appears to have better regression coefficients, with a maximum adsorption capacity range (208.33 - 223.21 mg/g). The resorcinol adsorption was strongly dependent on solution pH, and the solute removal become significant at pH @ pHpzc.
Thermodynamic parameters: ∆H°, ∆S° and ∆G° were computed from the experimental data. These values show that the adsorption is endothermic and spontaneous process. Moreover, the relative value of ∆Hads (34.506 kJ/mol) confirms a physical adsorption.
Kinetics of adsorption was investigated and the data were treated according to pseudo-first-order, pseudo-second-order and intra-particle diffusion models. It was found that the adsorption process of resorcinol onto activated carbon follows pseudo-second-order model.
Keywords: Adsorption equilibrium, activated carbon, resorcinol, kinetics, thermodynamics