Adsorption of methyl violet onto granular activated carbon: Equilibrium, kinetics and modeling

A batch system was applied to study the adsorption of methyl violet from aqueous solution by granular activated carbon. The adsorption studies include both equilibrium and kinetics. Equilibrium data were mathematically modeled using the Langmuir–Freundlich isotherm. The equilibrium data were fitted to the isotherm with n = 1 very well. Maximum adsorption capacity of 0.095 g/g at equilibrium was achieved. The kinetics of adsorption were evaluated by pseudo-first-order and pseudo-second-order models. Also extended geometric method has been applied to estimate the adsorption and desorption rate constants of Langmuir kinetics. By the obtained concentration-independent rate constants, the kinetics of adsorption were modeled by Langmuir kinetics. The stochastic numerical simulation has been applied to simulate the adsorption kinetic data of methyl violet at different concentrations.