Dynamic change of copper in fly ash during de novo synthesis of dioxins.
Although many researchers have reported that copper chloride is an important catalyst that generates relatively large amounts of dioxins in heat experiments involving model fly ash, details on the behavior of copper during the process are still unavailable. In this study, we used in situ XANES experiments involving one type of real fly ash, which originated from a municipal solid-waste incinerator (MSWI), and two fly ash models to investigate the behavior of copper in fly ash at temperatures that are suitable for de novo synthesis, which is the major formation route for dioxins during waste incineration and thermal processes. Cupric compounds in real fly ash and model fly ash A(CuCl2.2H2O + activated carbon (AC) + boron nitride (BN)) were reduced to cuprous compounds or elemental copper at low temperatures. The changes in the Cu XANES spectra of real fly ash were similar to those of model fly ash A and those of an oxychlorination catalyst. In model fly ash B (CuO + AC + KCl + BN), CuO did not vary dramatically in the temperature range studied. In this study, we found strong evidence that oxychlorination, the key mechanistic step in the formation of dioxins, occurred in both real MSWI and model fly ash.
Takaoka
Masaki
M
Departments of Urban & Environmental Engineering, Graduate School of Engineering, Kyoto University, Yoshidahon-machi, Sakyo-ku, Kyoto 606-8501, Japan. takaoka@epsehost.env.kyoto-u.ac.jp
Shiono
Atsuhiro
A
Nishimura
Kohei
K
Yamamoto
Takashi
T
Uruga
Tomoya
T
Takeda
Nobuo
N
Tanaka
Tsunehiro
T
Oshita
Kazuyuki
K
Matsumoto
Tadao
T
Harada
Hiroki
H
D000393:Air Pollutants / Q000032:analysis*; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D060729:Coal Ash; D003300:Copper / Q000737:chemistry*; D004147:Dioxins / Q000032:analysis* / Q000737:chemistry; D017745:Incineration; D007700:Kinetics; D008956:Models, Chemical; D052638:Particulate Matter; D013057:Spectrum Analysis; D014965:X-Rays
D000393:Air Pollutants; D060729:Coal Ash; D004147:Dioxins; D052638:Particulate Matter; D002244:Carbon; D003300:Copper; C029892:cupric chloride