Formation of dioxins during the combustion of newspapers in the presence of sodium chloride and poly(vinyl chloride)

Exhaust gases from the combustion of newspaper alone, from branches of Lond on plane tree alone, and from newspapers mixed with sodium chloride (NaCl), polyethylene, or poly(vinyl chloride) (PVC) were collected. The samples we re analyzed for dioxins by gas chromatography/mass spectrometry. Total amou nts of dioxins found in the samples were 0.186 ng/g from newspapers alone, 1.42 ng/g from the branches of London plane, 102 ng/g from newspapers impre gnated with sodium chloride (Cl wt % = 3.1), 101 ng/g from newspapers impre gnated with sodium chloride mixed with PVC (Cl wt % = 2.6), and 146 ng/g fr om newspapers mixed with PVC (Cl wt % = 5.1), Samples with a higher chlorid e content produced more dioxins, and there is a clear correlation between d ioxin formation and chloride content. The amount of dioxins formed in the s amples according to the number of chlorides was Cl-5 > Cl-4 > Cl-6 > Cl-7 > Cl-8 in PCDD isomers and Cl-4 > Cl-5 > Cl-6 > Cl-7 > Cl-8 in PCDF isomers, except in the case of newspapers alone. Benzofurans composed 78-92% of the total dioxins formed in the exhaust gases. The higher the number of the ch lorides, the lower the production of benzofuran observed. NaCl vaporized at the temperature of the flame used for combustion of the samples (760-1080 degreesC). The results indicate that NaCl and PVC contribute significantly to dioxin formation from waste materials combusted in incinerators.