Received for review July 31, 2007

Revised manuscript received October 11, 2007

Accepted October 19, 2007

Abstract:

To gain a more complete understanding of the impact of sulfur oxides on mercury capture by activated carbon, continuous mercury concentration measurements were made downstream of a packed sorbent bed. Previous research from this laboratory, which is presented in a companion study, indicated that the mercury capacity of activated carbon during a 6 h exposure to mercury-laden simulated flue gas was inversely proportional to the S⁶⁺ content of the carbon. The results presented here indicate that high S⁶⁺ content limits both the 6-h capacity of activated carbon and the initial mercury removal efficiency. The observed reduction in initial mercury removal efficiency verifies the assumption that the 6-h mercury capacity is indicative of in-flight mercury capture efficiency during activated carbon injection. The activated carbon sample with the highest sulfur content tested here captured a minimal amount of mercury; however, this sample oxidized ~30% of the incident Hg⁰ at 100% breakthrough. This finding suggests that there are multiple available sites for mercury interaction with the sorbent surface, and that capture and oxidation occur at different surface sites.

Download the full text: PDF | HTML