Kinetics and Mechanism Study of Mercury Adsorption by Activated Carbon in Wet Oxy-Fuel Conditions

In this article, four kinetic models including intraparticle diffusion, pseudo-first-order, pseudo-second-order, and Elovich kinetic models were applied to explore the internal mechanism of mercury adsorption by activated carbon in wet oxy-fuel conditions. Results indicated that the pseudo-second-order model and Elovich kinetic model could accurately describe the adsorption process, which meant that chemical adsorption played an important role in the adsorption of mercury by activated carbon. The intraparticle diffusion model indicated that internal diffusion was not the only step to control the entire adsorption process and did not have an inhibition effect on mercury removal. Meanwhile, the external mass transfer process is more effective in controlling the mercury adsorption process of activated carbon according to the fitting result of the pseudo-first-order model. According to the obtained kinetic parameters, the intraparticle diffusion rate was improved with the increasing bed height. In addition, the higher temperature inhibited the external mass transfer, which was not conducive to the adsorption of mercury by activated carbon in wet oxy-fuel conditions.