Influence of metal oxides on PCDD/Fs formation from pentachlorophenol.
Chlorophenols (ClPhs) are considered as important precursors for PCDD/Fs formation. The influences of series of metal oxides including MgO, Al2O3, CaO, BaO, TiO2, V2O5, MnO2, Fe2O3, Co3O4, CuO, Ag2O, ZnO, HgO, SnO, PbO, La2O3, CeO2, and Eu2O3 on PCDD/Fs formation from pentachlorophenol (PCP) were investigated in a laboratory-scale reactor. The results indicated that most of the above metal oxides have obvious suppressing effects on the total amount of PCDD/Fs formation from precursor PCP except for CuO, ZnO, MnO2, TiO2 and Co3O4 with promotion effects at 280 degrees C for 2 h. Although MgO, Al2O3, Fe2O3, PbO, La2O3 and Eu2O3 could reduce the amount of octachlorinated dibenzo-p-dioxin (OCDD), they promote the formation of more toxic 1,2,3,4,6,7,8-HpCDD at the same time. The total suppressing efficiencies of several metal oxides including CaO, BaO, PbO, Ag2O, HgO and SnO which have lower Z/r (charge to radius ratio) <2 are all over 90%. The theories of generalized acid-base and atomic parameter (Z/r) were used to speculate the effecting mechanisms. The factors including time and temperature on suppressing efficiencies of CaO, BaO and PbO have also been studied in the present paper. The results showed that the total suppressing efficiencies of CaO, BaO and PbO increase with the increase of heated time and temperature.
Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
Yong
Y
Qian
Minghui
M
Zheng
Wenbin
W
Liu
Xiaodong
X
Ma
Bing
B
Zhang
D000397:Air Pollution / Q000517:prevention & control; D001572:Benzofurans / Q000138:chemical synthesis*; D000072338:Dibenzofurans, Polychlorinated; D006358:Hot Temperature; D017745:Incineration; D008670:Metals / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D010416:Pentachlorophenol / Q000737:chemistry*; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D013997:Time Factors
D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D008670:Metals; D010087:Oxides; D000072317:Polychlorinated Dibenzodioxins; D010416:Pentachlorophenol