Modeling of Mercuric Chloride Removal by CuCl2-Impregnated Activated Carbon Sorbent in a Fabric Filter

A model for the physical adsorption of mercuric chloride (HgCl2) onto raw activated carbon (AC) and 4 and 10% CuCl2-impregnated activated carbon (CuCl2-AC) sorbents in a fabric filter was studied on the basis of the adsorption equilibrium and kinetics. Sorbent loading, particle size, filtration time, and CuCl2 loading onto AC were found to be the major factors determining a HgCl2 removal efficiency. Although high sorbent loading and small sorbent particle size result in high HgCl2 removal efficiencies, the inlet HgCl2 concentration and superficial gas velocity were found to have little impact on HgCl2 removal. Our operation case study result shows that sorbent injection for a short duration at a high loading followed by the discontinuation of the injection until a cleaning cycle can significantly save a total sorbent amount with high sorbent utilization, while the same amount of HgCl2 is removed. The adsorption of HgCl2 onto raw AC and CuCl2-AC in the filter cake was found to be primarily governed by the adsorption capacity difference in the Langmuir adsorption kinetic expression. The study results demonstrate how fundamental adsorption equilibrium and kinetics can be used to design a sorbent and predict its performance in a fabric filter. A comparison of the current model predictions was also made with pilot-scale field data available in the literature.