Polychlorinated Dibenzo-p-dioxins and Dibenzofurans Formation in Incineration: Effects of Fly Ash and Carbon Source

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• 作者：Peter W. Cains ; Linda J. McCausland ; Alwyn R. Fernandes ; and Patrick Dyke
• 刊名：Environmental Science & Technology
• 出版年：1997
• 出版时间：March 1997
• 年：1997
• 卷：31
• 期：3
• 页码：776 - 785
• 全文大小：363K
• 年卷期：v.31,no.3(March 1997)
• ISSN：1520-5851

文摘

Research aimed at understanding polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) formationincombustion and incineration processes constitutes animportant component in developing strategies forcontrollingtheir emission. Incinerator ashes from six differentprocesssources have been examined and characterized in termsof their behavior with respect to PCDD/F formation inlaboratory experiments. The effects of varying thecarboncontent of one ash has been investigated by replacingthe native carbon content with activated charcoals and pyrocarbons from paper and PVC. Analysis of homologuetotals and full isomer profiles indicate that PCDDs tendtoform in preferential isomer groups, while PCDF isomersare distributed more broadly. PCDD formation isconsistentwith condensation of chlorophenols, together with stepwisechlorination and dechlorination. Experiments with apentachlorophenol precursor show that fly ashes are morereactive dechlorinators than model systems, probably dueto the presence of alkali elements. PCDF formationprobably occurs via condensation of nonchlorinated phenolfollowed by chlorination of the dibenzofuran skeleton;thisgives schemes of formation for both PCDDs and PCDFsthat start with phenol. Demonstration of the formationofphenols in ashes and simulates is not currentlysatisfactory,but aromatization of residual aliphatic oils is believed tobethe most probable source. A relationship was foundbetween the amounts of such oils present on the originalcarbons/ashes and the quantities of PCDD and PCDFformed.