废物焚烧厂烟气中PCDD/Fs和PCNs的排放特征

采用同位素内标稀释高分辨气质联用分析法，对废物焚烧厂的烟气样品PCDD/Fs和PCNs进行了测定，分析了其排放特征以及相关性，为有组织排放的PCDD/Fs和PCNs的控制提供理论依据.实验结果表明，空白实验中未发现明显的背景干扰；样品中PCDD/Fs的采样内标回收率范围为74.0%~90.1%，提取内标的回收率范围为53.3%~120.0%，均符合US EPA23和CHN HJ77.2-2008的质量控制标准；PCDD/Fs的同系物浓度均随着氯取代数目的增加而增加，而PCNs同系物则随着氯取代数目的增加表现出先增大后减小的规律.同系物之间的皮尔森相关系数分析结果可知，这两类污染物相邻同系物相关性系数明显大于非相邻同系物相关性系数，表明低氯代同系物可能是生成高氯代同系物的一个重要途径.此外，PCNs和PCDD/Fs同系物的线性相关分析结果表明，一些PCNs化合物（PeCN、HxCN、HpCN、OCN）与某些PCDD/Fs（OCDD、PeCDF、HxCDF、HpCDF）具有良好的相关性（R²=0.55~0.78），由此推断在废物焚烧过程中这些同系物可能具有相类似的生成机制.

Emissions characteristics analysis of PCNs and PCDD/Fs from waste incinerators stack gas

In this study, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated naphthalenes (PCNs) in stack gas of waste incinerators were monitored by using high resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS) with isotope internal standard dilution method. Emissions characteristics and correlation of the two groups' pollutants were also discussed, which could provide helpful theoretical foundation for controlling PCDD/Fs and PCNs emissions from organized sources. The results showed that, (1) no obvious PCDD/Fs or PCNs contamination was found in blank experiments; (2) the recoveries of the added internal standard for sampling and extracting satisfied the requirements of US EPA23 and CHN HJ77.2-2008, which were 74.0%~90.1% and 53.3%~120.0%, respectively; (3)for PCDD/Fs, the concentration of homologues were increased with the increase of the chloride numbers, while for PCNs, the homologues firstly increased then decreased with the increase of the chloride numbers. In addition, the Pearson correlation coefficients of the adjacent homologues of both PCDD/Fs and PCNs were higher than that of the non-adjacent ones, which may reveal that the chlorination of low chlorinated homologues was an important pathway of the formation of higher chlorinated ones. High linear correlation were found from some PCNs (i.e., PeCN, HxCN, HpCN and OCN) and some PCDD/Fs (i.e., OCDD, PeCDF, HxCDF and HpCDF) (R²=0.55~0.78), which may suggest similar formation mechanism of these homologues during the process of waste incineration.