Volume 12, No. 2, April 2012, Pages 228-236 PDF(299 KB)
PCDD/F Formation Catalyzed by the Metal Chlorides and Chlorinated Aromatic Compounds in Fly Ash
Yu-Te Chin1, Chieh Lin1, Guo-Ping Chang-Chien2, Yu-Min Wang3
1 Department of Environmental Engineering and Science, National Pingtung University of Science and Technology, No. 1 Shieh-Fu Rd., Nei Pu Township, Pingtung County 912, Taiwan
2 Department of Chemical and Materials Engineering and Super Micro Mass Research & Technology Center, Cheng-Shiu University, Kaohsiung County 83347, Taiwan
3 Department of Civil Engineering Technology, National Pingtung University of Science and Technology, No. 1 Shieh-Fu Rd., Nei Pu Township, Pingtung County 912, Taiwan
The entrained fine fly ash particles carried into the post-combustion region and collected by air pollution control devices were capable of such surface-mediated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) formation. The secondary formation of PCDD/Fs in the flue gas and ash from the municipal solid waste incinerator (MSWI) systems has attracted considerable public concern. The objective of this study was to examine reactions in fly ash from an municipal solid waste incinerator (MSWI) operated with metal chlorides and chlorinated aromatic precursors. When 10 wt% FeCl2, ZnCl2 and CuCl2 were added onto the fly ash medium, the PCDD/Fs concentration is 8.8, 25.5 and 369.5 ng/g, respectively. This indicates that the formation of PCDD/Fs was significantly increased by CuCl2. In the case of CaCl2 addition, the results showed that it acts in a minor role as a catalyst to promote the formation of PCDD/Fs. In addition, the results of adding HgCl2 has no transformation effect on the formation of PCDD/Fs in the residue and gas phases. Moreover, in an experiment using chlorinated aromatic precursors, the formation of PCDD/Fs was significantly increased by pentachlorophenol (PCP). This study suggests that the filter cake ash treatment should be studied extensively to control dioxin yields on the fly ash matrix.
Fly ash; PCDD/Fs; Metal chloride; Chlorinated aromatic compounds; Catalysis.