超积累植物热解中重金属迁移及渗滤特性研究

Fate and leaching characteristic of heavy metals during pyrolysis of hyperaccumulator

在管式炉上研究了土壤修复后超积累植物蜈蚣草(Pteris vittata)热解过程中Zn、Cd、Cr、Cu、Pb和Ni的迁移规律和底渣的渗滤特性.结果表明,高温促进重金属的迁移,挥发强度依次是Pb≈Cd>Zn>Cr>Cu≈Ni;热解温度在500~900℃有利于重金属在底渣中富集,有利于后续重金属回收利用,实现资源化;底渣的渗滤特性受温度影响,随温度升高,底渣的重金属浸出量减小;底渣中重金属浸出率整体呈现出下降趋势,说明热解使得底渣中重金属向更稳定形态转变.

The pyrolysis experiments of Pteris vittata,a kind of hyperaccumulators after soil remediation,were carried out in a laboratory-scale tube furnace to study the fate and leaching characteristic of heavy metals（ Zn,Cd,Cr,Cu,Pb and Ni）. The results showed that a higher temperature was effective for the evaporation of heavy metals and their evaporation rates were ordered as Pb≈CdZnCrCu≈Ni. The pyrolysis at temperature range of 500 ~ 900 ℃ was beneficial for the enrichment of heavy metals in solid residue,facilitating their recovery. Temperature had significant effects on the leaching characteristic of heavy metals. The leaching rate decreased with the increase of temperature,indicating that the pyrolysis of Pteris vittata transformed heavy metals to more stable forms.