烧结厂烟尘和静电除尘器灰尘中二噁英的分布特征

LEVELS AND CHARACTERISTICS OF POLYCHLORINATED DIBENZO-P-DIOXIN AND POLYCHLORINATED DIBENZOFURAN IN FLY ASH AND ESP DUSTS FROM A CHINESE SINTER PLANT

研究了烧结厂烟道烟尘和静电除尘器灰尘中二噁英的浓度和分布特征.结果显示,烧结台车机头烟道烟尘和机尾烟道烟尘中二噁英的总含量分别为867.49±215.41和170.35±51.12pg.Nm-3,毒性当量分别36.53±4.47和9.13±2.40pgWHO-TEQ.Nm-3;机头静电除尘器灰尘和机尾静电除尘器灰尘的总含量分别为2423.59±100.01和157.29±36.83pg.g-1dw,毒性当量分别71.67±0.62和7.50±1.08pgWHO-TEQ.g-1dw.烧结中二噁英的分布以PCDFs为主,而且PCDFs各同系物的浓度与Cl原子取代数目呈负相关(r2=0.98).在WHO-TEQs中2,3,4,7,8-PeCDF的贡献最大,占总TEQ值的45%左右.

The dusts from the former and later electrostatic precipitator （ESP） and the fly ash from the former and later chimney were collected in a Chinese sinter plant. The samples were analyzed for PCDD/Fs by HRGC/HRMS-MID according to US EPA 1613B method and were calculated by WHO-TEFs. The total concentrations of PCDD/Fs found in the dusts from the former and the later ESP were 2423.59±100.01 pg·g^-1 and 157.29±36. 83 pg·g^-1 with WHO-TEQ values of 71.67±0.62 pg·g^-1 and 7.50±1.08 pg·g^-1 respectively, meanwhile in the former and the later fly ash the values were 867.492 ± 215.41 and 170.35 ± 51.12 pg·N m^-3, 36.53 ± 4. 47 and 9. 13 ± 2.40 pg TEQ·N m^-3 , respectively. Moreover, it was found that PCDFs were the dominant congeners, the concentration of which showed a negative correlation with the number of substituted Cl. Among PCDD/Fs congeners, 2,3,4,7,8-pentachlorodibenzofuran （PeCDF） was found to constitute about 45% of the total WHO-TEQ. The results showed the drying area in sinter belt was suggested to be the main. area of dioxins production. Although the concentration of PCDD/Fs in sintering was lower than that in municipal solid waste incinerator, the emission of dioxins from sintering should be gained more attentions due to the huge emission of exhaust gas.