(29g) Modeling of Mercuric Chloride Removal Using Raw Activated Carbon

The physical adsorption of mercuric chloride (HgCl₂) onto raw activated carbon was studied in an entrained flow and fabric filter based on adsorption kinetics and equilibrium data obtained from fixed-bed system. An operation study was conducted where high HgCl₂ removal was achieved by injecting raw activated carbon sorbent at a high loading for a short time followed by no sorbent injection until the end of the cleaning cycle. This injection method helped in increasing sorbent utilization for the same amount of HgCl₂ removed as compared to continuous injection. The pressure drop across the filter cake was estimated using Darcyâ??s law. The pressure drop across the filter cake was found to be within the operating limits for a typical fabric filter. The capture performance for mercury in an entrained flow was found to be insignificant with a removal efficiency of <1%. It was found that 90% HgCl₂ removal efficiency was achieved within the first 9 min of filter cake residence time using the injection method. The role of internal and external mass transfer was studied in detail. It was found that while the external mass transfer played an insignificant role, the role of internal mass transfer was pronounced. The result shows that fundamental adsorption kinetics and equilibrium can be used to predict HgCl₂ capture.