Influence of metal oxides on PCDD/Fs formation from pentachlorophenol

Abstract Chlorophenols (ClPhs) are considered as important precursors for PCDD/Fs formation. The influences of series of metal oxides including MgO, Al 2 O 3 , CaO, BaO, TiO 2 , V 2 O 5 , MnO 2 , Fe 2 O 3 , Co 3 O 4 , CuO, Ag 2 O, ZnO, HgO, SnO, PbO, La 2 O 3 , CeO 2 , and Eu 2 O 3 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, MnO 2 , TiO 2 and Co 3 O 4 with promotion effects at 280 °C for 2 h. Although MgO, Al 2 O 3 , Fe 2 O 3 , PbO, La 2 O 3 and Eu 2 O 3 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, Ag 2 O, HgO and SnO which have lower Z / r (charge to radius ratio) 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.