Polycyclic aromatic hydrocarbons (PAHs) and mutagenicity in air emissions from the two-stage incineration of polystyrene with various metallic salt additives

The yield of 14 PAHs and soots were more with BaCl₂ or NaCl additive than those without metallic chloride additives. This indicated that metallic chloride additives could promote the reaction sequence towards the growth and coagulation reaction of soots from PS pyrolysis. When the second-stage temperature increased to the critical temperature, black tar formed and the concentration of 14 PAHs was 10 μg/g PS. Pha, Flu and Pyr were major species found among the 14 PAHs. Log K values, the ratios between the PAHs in gas phase and the PAHs in solid phases (per particulates weight; 1/mg) increased as the stage-two pyrolysis temperature increased. When the stage-two incineration system was controlled at 900°C as were various oxygen supplies, the maximum value of log K occurred at 0.0525 O₂ (nl/min) and log K value decreased as the oxygen supply increased. When oxygen supply was increased from 0 to 0.210 nl/min, the mutagenicity of particulates extracts from the PS incineration with metallic chloride additives was still more stronger.