Fundamental study on removal of harmful heavy metal from residual ash of burnt urban waste by means of polyvinyl chloride

城市垃圾焚烧后的残灰中含有大量的重金属氧化物。由于含有重金属氧化物，因此不可能将残灰倾倒在填海土地上。本文的研究对象是解决这一问题的基础性研究。尝试将重金属氧化物与聚氯乙烯（PVC）在反应室中反应，然后将产生的气态氯化物从反应室中除去。当问题解决后，PVC的浪费量也减少了。以化学药剂合成的灰为样品，不含真灰。合成灰的溶剂为Al_2O_3-CaO-SiO_2。溶质为CdO、Cr_2O_3、Cu_2O、PbO和ZnO。结果表明，CdO、Cu_2O、PbO和ZnO都容易被氯化。另一方面，用PVC法氯化Cr_2O_3是困难的。氯化反应速率可表示为重金属氧化物浓度的一级表观反应方程。速率常数的温度依赖性可以用Arrhenius方程表示。

Residual ash of burnt urban waste contains large amount of heavy metal oxides. Due to the heavy metal oxides, it is impossible to dump the residual ash on a reclaimed land. An object of the research is fundamental study to dissolve the issue.It is attempt that the heavy metal oxides are reacted with polyvinyl chloride (PVC) in a reaction chamber, then produced gaseous chlorides are removed from the chamber. When the issue is dissolved, volume of wasted PVC is reduced also.No real ash but synthetic ash made from chemical agent are tested as sample. Solvent of the synthetic ash is Al_2O_3-CaO-SiO_2. Solutes are CdO, Cr_2O_3, Cu_2O, PbO and ZnO.It is revealed that CdO, Cu_2O, PbO and ZnO can be easily chlorinated. On the other hand chlorination of Cr_2O_3 by means of PVC is difficult.Chlorination rates can be expressed as apparent first order reaction equation for concentration of heavy metal oxide. Temperature dependency of the rate constants can be expressed by Arrhenius equation.