The adsorption of toluenediamine from the wastewater by activated carbon in batch and fixed bed systems

Abstract

This paper investigated the adsorption behavior of toluenediamine on activated carbon in batch and fixed bed systems, respectively. The adsorption isotherms could be well fitted by the Langmuir adsorption equation and the kinetics of adsorption followed the pseudo-second-order model. The thermodynamic parameters for the process of adsorption have been estimated and the results indicated the physical, exothermic and spontaneous nature of adsorption. With the adsorption equilibrium constant and the kinetics of adsorption determined from separate experiments in the batch reactor, the design parameters of the fixed bed column were evaluated by the experiments. Based on this analysis, the overall liquid-phase volumetric mass-transfer coefficient of the fixed bed ( K F α v) was calculated from the nonlinear wave propagation theory and Weber's theory. It also suggested that the overall liquid-phase volumetric mass-transfer coefficient of the fixed bed was independent of the bed depth but increased with feed flow rate.