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EVALUATION AND USE OF STAND-ALONE COMMERCIAL PHOTOLYTIC CONVERTERS FOR CONVERSION OF NO2 AND NO
Citation:
Kronmiller, K. G. AND W A. McClenny. EVALUATION AND USE OF STAND-ALONE COMMERCIAL PHOTOLYTIC CONVERTERS FOR CONVERSION OF NO2 AND NO. Presented at Symposium on Air Quality Measurement Methods and Technology, Research Triangle Park, NC, April 20-22, 2004.
Impact/Purpose:
1. Provide the Agency with semi-continuous and real-time instrumentation for its monitoring of ozone, ozone precursors, and reaction products of ozone formation.
2. Provide the Agency with semi-continuous and real-time instrumentation for its monitoring of water-soluble PM components and water-soluble atmospheric gases.
Description:
Two types of stand-alone photolytic converters of nitrogen dioxide (NO2) to nitric oxide (NO) are now commercially available for use with NO, ozone (O3) chemiluminescence detector (CLD) monitors for the measurement of NO2. Both units have been tested for interferences resulting from photolysis of nitrous acid (HONO) and from the decomposition of peroxyl acetyl nitrate (PAN). One unit (Model 81800, Spectra-Physics Stratford, CT) is based on the use of a broadband source (short-arc mercury lamp) and incorporates a source cooler. This unit has been used for two month-long field studies, one in May 2002 and a second in October 2003. The results indicate that the converter is robust and reliable with conversion efficiencies (CEs) of 35-70% depending on the airflow rate through the converter. The second commercial unit (Droplet Measurement Technologies-Sonoma Technology, Inc., Petaluma, CA) is based on a light-emitting diode (LED) array with output emission wavelengths centered near 390 nm with emission bandwidths of typically 20 nm. This unit is being field tested for use as part of ongoing tests. Based on results so far, the prospect of using one of the stand-alone converters with an external, heated metal (molybdenum) converter and a chemiluminescence monitor to measure NO, NO2, and NOY (e.g., NO, NO2, HNO3, HONO, HO2NO2, NO3, N2O5, and organic nitrate) seems reasonable.
This work has been partially funded by the United States Environmental Protection Agency under Contract 68-D-00-206 to ManTech Environmental Technology, Inc. This paper has been reviewed in accordance with the Agency's peer and administrative review policies and approved for presentation and publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use