The kinetics of adsorption of methylene blue from aqueous solution onto activated carbon prepared from palm kernel shell has been investigated. The time dependent studies showed a rapid adsorption in the first ten minute. A batch sorption model based on the assumption of the pseudo first and second order mechanism, were applied to predict the rate constants. The adsorption process follows the pseudo-second order kinetic, having a correlation coefficient in the range between 0.98 and 1. The pseudo second order rate constant k2 was found to generally decrease from 1.79 to 4.5 x 10-2 as the initial concentration increased from 5 to 25 ppm but increased from 4.9 x 10-2 to 2.3 x 10-1 with increased temperature, suggesting that the adsorption process is endothermic. Intra-particle diffusion was confirmed as one of the rate determining steps; as such the adsorption mechanism is controlled by particle diffusion rather than film diffusion.
