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Show levels of conversion which is consistent with the results from conventional direct photochemical treatment processes. However, the model predicts that 9 9 % of the T C E may be destroyed by at 500°C using a xenon arc illumination system delivering 100 w/cm2 of radiant energy. Considering that the 18.1 w/cm2 xenon arc radiation used in the laboratory was generated with a single 1 k W lamp, intensities in the 100-200 W / c m 2 range should be readily achievable with currently available lamp technology. Furthermore, lamps other than xenon arc, pulsed lamps, or even xenon arc lamps with enhanced U V output (i.e., xenon arc lamps manufactured with high grade U V transparent envelopes rather than simple fused quartz), may prove more efficient than the illumination system used in the laboratory tests. Summary The data obtained thus far clearly shows that the photothermal detoxification process is capable of efficiently destroying organic air toxics. Furthermore, the process is capable of destroying associated organic PICs, resulting in the complete mineralization of the waste feed. Spectroscopic data illustrates that organic molecules absorb near U V radiation with increasing efficiency at high temperatures and that the rate of decomposition from the excited state also increases with temperature. These features give rise to a photothennal detoxification process that operates far more efficiently than conventional photochemical treatments and at temperatures less than that for thermal treatments. This makes the process ideally suited for non-combustible process streams such as those from soil vapor extraction and thermal desorption operations, chemical process off-gas streams, or even post-combustion air pollution control. The immediate future work on the photothermal process includes acquiring data on a wide variety of volatile air toxics, including complex hydrocarbon mixtures, to better define the types of wastes which are candidates for photothennal treatment, and which wastes would pose particularly difficult challenges. In the process of obtaining this infonnation, a larger pool of data will become available on PIC formation and destruction, and determine what types of PICs may present a particular challenge to the process. Once the laboratory data is available, a detailed process computer model will be constructed to predict system performance with various reactor vessel configurations, lamp types, and exposure conditions. This will result in the detailed design for a prototype photothermal detoxification unit (PDU) designed for processing the exhaust stream from soil vapor extraction and thermal desorption operations. Acknowledgements This work was supported, in part, by the U.S. Environmental Protection Agency and the U.S. Department of Energy (CR-818614-01-0 and CR-819594-01-0). Thanks are extended to these organizations for their support. The authors would also like to acknowledge the National Renewable Energy Laboratory for their help and support (DE-AC03-845F15354 and XX-6- 06082-1). 14 111-19 |