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A sensor for organic compounds in wastewater

: Scharring, S.; Hahn, P.; Cosmo, O.; Tacke, M.

Deutsche Gesellschaft für Chemisches Apparatewesen, Chemische Technik und Biotechnologie e.V. -DECHEMA-, Frankfurt/Main:
Abstracts of the lecture groups "Environmental Technology and Fundamentals of Laser-aided In-situ Soil Analysis"
Frankfurt/Main: DECHEMA, 2000
International Meeting on Chemical Engineering, Environmental Protection and Biotechnology (ACHEMA) <26, 2000, Frankfurt/Main>
Conference Paper
Fraunhofer IPM ()
waste water; process control; MIR; SOC; Online-Monitoring; evanescent field spectroscopy; organic compound; polymer coating; analyte enrichment

Subject is a cost effective sensor for on-line control of wastewater and process water. Organic components are measured in water by the absorption of light by their C-H-valence vibrations in the mid infrared. Evanescent field spectroscopy with a polymer coated fibre is employed in order to eliminate water background absorption. The enrichment of the analyte in the polymer coating leads to an increase of its absorption signal. Starting with FTIR-measurements the spectroscopic effort can be reduced using a broadband IR source combined with four spectral filters. Detection limits of 10 ppm toluene in water and 10 minutes for analyte enrichment have been achieved.