Dynamics and model research on the electrosorption by activated carbon fiber electrodes

Abstract

Electrosorption is a new emerging technology for micro-polluted water treatment. To gain a more accurate understanding of the mass and charge transfer process of electrosorption, the electrosorption performance of activated carbon fiber (ACF) electrodes with various concentrations was studied. In this paper, quasi-first-order and quasi-second-order dynamic equations, and an intra-particle diffusion equation were used to describe the electrosorption behaviors. It is believed that the electrosorption process is dominated by physical adsorption for ACF material, and the most important rate control steps in this process are intra-diffusion and electromigration steps. Based on the experimental results and modified Donnan model theory, a considerable electrosorption dynamic model which considered the influence of physical adsorption and the intra-diffusion resistance was proposed. This model quantitatively described the salt adsorption and charge storage in the ACF electrode and can fit the experimental data well.