Experimental and Kinetic Study of Mercury Adsorption on Various Activated Carbons in a Fixed-Bed Adsorber

This study investigated experimentally and theoretically the characteristics of mercury sorption by activated carbons. Experiments were carried out in a fixed-bed mercury sorption facility composed of a mercury permeation tube embedded in an isothermal water bath, a fix-bed adsorber enclosed in a furnace, and an on-line GC for mercury measurements. The proposed sorption model involved the coupling of a kinetic model based on the mechanisms of surface equilibrium and external mass transfer, and a material balance model based on the tank-in-series approach. Three different equilibrium expressions were used in the model, i.e., the Henry's Law, the Langmuir isotherm, and the Freundlich isotherm. In additional to kinetic simulations using the developed model, an equilibrium model was also used to simulate the thermodynamically preferred mercury species under the experimental conditions. The experimental results have indicated that the factors affecting the adsorption efficiency include the type of activated carbon, the adsorption temperature, the inlet mercury concentration, and the gas flow rate. The developed kinetic model has been found to describe well both the current experimental results and those reported in the literature.