Study on the Relationship between the Emission of Chlorine and UV/VIS Sensitive Organic Matter from Heating MSWI Baghouse Ash: Using an Optical UV7VIS Spectrometer as the On-Line Monitoring Sensor

摘要

In this study the baghouse ash (fly ash) from municipal solid waste incineration (MSWI) plants was heated in a fixed bed reactor, from 25 °C to 800 °C. An optical fiber UV/VIS spectrometer was employed as the real-time monitor to probe the emission behaviors of organic compounds. A two-dimensional (2D) correlation technique was used to specify organic matter existing in exhausted gas. Three adsorbents, including water, acetone and cyclohexane, were used to adsorb the organic and molecular chlorine in the gas emitted from the reactor. Concentrations of molecular chlorine (Cl_2, total organic carbon (TOC), and total inorganic carbon (TIG) in these adsorbents were analyzed to evaluate the reactions occurring in fly ash. We have found that generation temperatures of molecular chlorine were found mainly at 200 °C and 750 °C, which are attributed to the dechlorination of chlorinated-organic compounds and vaporization of heavy metal chlorides, respectively. 2D correlation UV/VIS spectra are useful to extract valuable information from the one-dimensional UV/VIS of emitted gas. The identified organic species would be diethyl-amine, dibenzo-p-dioxin, thioxanthone, 1,4-dichloro-anthraquinone, benzene, 1-naphthalene azo, azulene, dibenzanthrone, l-chloro-4-notroso-benzene and 4-nitro-toluene. The emission behaviors of dibenzo-p-dioxin, thioxanthone, azulene and dibenzanthrone were reported, and we concluded that the chlorine emission is almost always earlier than the release of these UV/VIS-sensitive organic compounds.