PVC浓度对热处理过程中Pb迁移转化的影响

生活垃圾热处理过程中含氯化合物的存在会使重金属转化为颗粒更小、更易挥发的重金属氯化物，扩大其环境影响.本文采用热分析和管式炉模拟法，研究在不同气氛下城市生活垃圾中典型有机氯化物--聚氯乙烯（PVC）对重金属Pb迁移转化的影响.结果表明，PVC和PbO共存的体系中，PVC在250℃左右热分解产生HCl，并与PbO反应生成PbCl₂（501℃左右开始挥发）而促进Pb迁移进入烟气.当Cl：Pb物质的量比为2，3，5和10时，在空气气氛下PVC浓度的增加对Pb的挥发没有显著影响，而在氮气气氛下，Cl：Pb=3时，Pb挥发率最大，达到88.19%，Cl：Pb=2时，Pb挥发率最小，为68.60%.

Effect of PVC concentration on the transformation and migration of Pb during thermal treatment

The migration and release of heavy metals during thermal treatment of municipal solid waste (MSW) is an environmental issue of great concern. Chlorine-containing compounds present in MSW could convert heavy metals into smaller particles and volatile chlorides during thermal treatment, thus cause serious environmental pollution. In this study, thermogravimetric analysis and tube furnace were used to investigate the effect of polyvinyl chloride (PVC) on the transformation and migration of Pb under different atmosphere. The results showed that PVC decomposed at 250℃, and then the released HCl reacted with PbO to form PbCl₂ (melting point: 501℃), which promoted the migration of Pb into the flue gas. The concentration of PVC (at the molar ratios of Cl:Pb = 2, 3, 5, and 10) had no significant effect on the volatilization of Pb under air atmosphere. While under N₂ atmosphere, the highest volatility of Pb could reach 88.19% at the molar ratio of Cl:Pb=3; the lowest volatility of Pb was 68.60% at the molar ratio of Cl:Pb=2.