Issues Related to Solution Chemistry in Mercury Sampling Impingers

• Published in: Journal of the Air & Waste Management Association (1995) 2001-05, Vol.51 (5), p.688-698
• Main Authors: Linak, William P., Ryan, Jeffrey V., Ghorishi, Behrooz S., Wendt, Jost O.L.
• Format: Article
• Language: English
• Subjects: Air Pollutants - analysis; Analysis methods; Applied sciences; Atmospheric pollution; Environmental Monitoring - methods; Exact sciences and technology; Incineration; Mercury - analysis; Mercury - chemistry; Pollution; Power Plants; Refuse Disposal
• ISSN: 1096-2247; 2162-2906
• DOI: 10.1080/10473289.2001.10464301

Analysis of Hg speciation in combustion flue gases is often accomplished in standardized sampling trains in which the sample is passed sequentially through a series of aqueous solutions to capture and separate oxidized Hg (Hg 2+ ) and elemental Hg (Hg 0 ). Such methods include the Ontario Hydro (OH) and the Alkaline Mercury Speciation (AMS) methods, which were investigated in the laboratory to determine whether the presence of Cl 2 and other common flue gas species can bias the partitioning of Hg 0 to front impingers intended to isolate Hg 2+ species. Using only a single impinger to represent the front three impingers for each method, it was found that as little as 1-ppm Cl 2 in a simulated flue gas mixture led to a bias of approximately 10-20% of Hg 0 misreported as Hg 2 + for both the OH and the AMS methods. Experiments using 100-ppm Cl 2 led to a similar bias in the OH method, but to a 30-60% bias in the AMS method. These false readings are shown to be due to liquid-phase chemistry in the impinger solutions, and not necessarily to the gas-phase reactions between Cl 2 and Hg as previously proposed. The pertinent solution chemistry causing the interference