Adsorption Kinetic study of methylene blue onto carbon from olive stones activated by phosphoric acid

Abstract

In this paper, batch kinetics data such as models proposed by first, second and pseudo-second order for methylene blue adsorption onto chemically activated carbon prepared from olive stones were calculated at three different temperatures (293, 303 and 313 K). The obtained results show that the adsorption was found to increase on increasing temperature. The data clearly indicate that the pseudo-second-order rate equation yields the best fit and the correlation coefficients of the pseudo second-order rate model for the linear plots are very close to 1 at various temperatures, suggesting that kinetic adsorption can be described by the pseudo-second-order rate equation. The rate constants for pseudo-second order are 1.24x10^-4, 1.25x10^-4 and 1.04x10^-4 g mg^-1 min^-1, and the activation energy for this process is 0.7557 KJ mol^-1. The half live times were determined and found to be ranging from 17 to 21 min at different temperatures. Moreover, the diffusion model involves two phases, which suggests that the adsorption process proceeds by surface sorption and intraparticle diffusion.