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ROLE OF SURFACE FUNCTIONAL GROUPS IN THE CAPTURE OF ELEMENTAL MERCURY AND MERCURIC CHLORIDE BY ACTIVATED CARBONS
Citation:
Ghorishi, S. B., R. Keeney, AND B K. Gullett*. ROLE OF SURFACE FUNCTIONAL GROUPS IN THE CAPTURE OF ELEMENTAL MERCURY AND MERCURIC CHLORIDE BY ACTIVATED CARBONS. Presented at Conference on Air Quality II, McLean, VA, 9/19-21/00.
Description:
The paper discusses using a laboratory-scale, fixed bed apparatus to study the role of surface functional groups (SFGs) in the capture of mercuric chloride (HgC12) and elemental mercury (Hgo) in nitrogen (N2) prior to flue gas atmosphere studies. The study focused on two activated carbons (FGD and PC-100, Norit Americas, Inc.) with different physical and chemical characteristics. SFGs may be acidic or alkaline. Acidic SFGs include carboxyl, lactone, hydroxyl, and carbonyl functionalities, while alkaline properties are believed to arise from two types of active sites, pyrone and chromene structures. The acidic and alkaline SFGs of as-received FGD and PC-100 were determined using surface titration. An attempt was made to correlate the number density of these SFGs to their ability to sorb Hgo nd HgC12. The activated carbons were then treated with acid and alkaline washes to neutralize their alkaline and acidic SFGs, respectively. The mercury capture capabilities of these treated carbons were then compared to those of untreated as-received samples. The initial hypothesis was that the number of alkaline SFGs should correlate with HgC12 capture. This was proveds not to be the case: rather, the concentration of surface chlorine (C1) sites was related to the HgC12 and Hgo capture. Acidic and alkaline SFGs play no role in the adsorption of Hgo and HgC12 by activiated carbons.