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IODIDE AEROSOL SORBENTS FOR MERCURY CAPTURE IN COMBUSTION EXHAUSTS
Citation:
Rodriguez, S., T. G. Lee, E J. Hedrick, AND P. Biswas. IODIDE AEROSOL SORBENTS FOR MERCURY CAPTURE IN COMBUSTION EXHAUSTS. Presented at EPA-DOE-PRI Mega Symposium Mercury Emissions Fate, Effects and Control, Chicago, IL, August 20-24, 2001.
Description:
Several sorbent processes are being studied for their feasibility for mercury capture. Mercury is different from the other heavy metals as it is not as chemically reactive (due to a filled outer electronic shell), thus making it difficult for sorbents to chemically trap it (a). A titania based sorbent was found to be effective due to its potential to oxidize the mercury on irradiation with uv light(b). During the development of impinger solutions for efficient capture of mercury for measurement by direct injection nebulization inductively coupled plasma mass spectrometry (c), we found out that in situ generated aqueous iodine, starting with potassium iodide solution, was very effective at capturing elemental mercury. In this study we demonstrate the effectivenss of potassium iodide aerosols at room temperature for capturing elemental mercury in gas streams.
The system consisted of a mercury feed unit, an atomizer for nebulizing potassium iodide solutions to generate a high surface area sorbent aerosol, a filter for effectively capturing the particles, followed by an impinger train to caputre the gase phase mercury species. Results of a series of experiments that were conducted will be discussed. The first phase was to characterize the KI generated sorbent particles, and the second phase focused on the caputre efficiencies. Rather high capture efficiencies (>99%) for elemental mercury were obtained using the potassium iodide sorbent particles. The capture mechanism will be discussed, along with the potential to scale up for applicability in pilot systems.