Adsorption of basic dye using activated carbon prepared from oil palm shell: batch and fixed bed studies

The feasibility of activated carbon prepared from oil palm shell to remove methylene blue from aqueous solutions was investigated through batch and column studies. Batch experiments were carried out to study the adsorption isotherm and kinetics at 30 degrees C, with the initial concentration of 50-500 mg/l and solution pH of 6.5. Equilibrium data were fitted to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. The equilibrium data were best represented by the Langmuir isotherm model, with maximum monolayer adsorption capacity of 243.90 mg/g at 30 degrees C. The adsorption process was found to be exothermic in nature. The kinetic data were fitted to pseudo-first-order, pseudo-second-order and intraparticle diffusion models, and it was found to follow closely the pseudo-second-order model. In column experiments, the effects of the initial dye concentration, bed height and flow rate on methylene blue adsorption were studied. The highest bed capacity of 40.86 mg/g was obtained using 100 mg/l initial dye concentration, 6 cm bed height and 20 ml/min flow rate.