Kinetic and isothermal studies on liquid-phase adsorption of 2,4-dichlorophenol by palm pith carbon

Adsorption studies were conducted to study the removal of 2,4-dichlorophenol (2,4-DCP) from aqueous solution on palm pith carbon under varying experimental conditions such as agitation time, adsorbent dose, pH and temperature. Higher 2,4-DCP was removed with decrease in the initial concentration of 2,4-DCP and increase in amount of adsorbent used. Kinetic study showed that the adsorption of 2,4-DCP on palm pith carbon was a gradual process. Adsorption capacities were 19.16 mg/g for the particle size of 250--500 mu m. The equilibrium time was 60 and 80 min for 10 and 20 mg/L and 100 min for both 30 and 40 mg/L phenol concentrations, respectively. Acidic pH was favourable for the adsorption of 2,4-DCP. Studies on pH effect and desorption showed that chemisorption seemed to play a major role in the adsorption process. Thermodynamic study showed that adsorption of 2,4-DCP on palm pith carbon was more favoured. The change in entropy (Delta S-0)and heat of adsorption (Delta H-0) of palm pith carbon was estimated as 30.72 J/mol/k and 7.16 kJ/mol, respectively. The high positive value of change in Gibbs free energy indicated the feasible and spontaneous adsorption of 2,4-DCP on palm pith carbon. The results indicated that palm pith carbon was an attractive candidate for removing phenols from wastewater. (C) 2006 Elsevier Ltd. All rights reserved.