萱草热解利用及重金属迁移规律研究

Study on pyrolysis utilization of Hemerocallis fulva and heavy metal migration

利用热解法处理富集重金属的萱草,以修复Pb单一污染、Zn和Cd复合污染的萱草为研究对象,研究温度对热解炭理化性质重金属形态迁移释放规律的影响。结果表明:当热解温度从400℃上升到800℃,两种热解炭产率呈下降趋势,从38.75%和40.05%下降至28.45%和26.71%,热解炭热值在11.18~15.62 MJ·kg^(-1)之间。此外,热解炭中重金属浓度随着热解温度升高而下降,在400℃~600℃时Pb富集在热解炭中,而Zn、Cd在生物炭中富集倍数均较低,大部分随着热解温度升高而进入到气相中。XRD表征结果表明热解炭中重金属主要以Pb3O4、Zn(OH)2和Cd(OH)2为主,并且出现少量金属单质。

Application of Hemerocallis fulva for remediation of Pb contaminated or Zn and Cd contaminated soil would produce a large amount of phytoremediation biomass.In this study,pyrolysis of H.fulva harvested from contaminated soil was conducted.The influence of temperature on the physicochemical properties of pyrolysis char,morphology and migration of heavy metals was investigated.The results showed that the yield of pyrolysis char decreased from 38.75%and 40.05%to 28.45%and 26.71%,respectively when the pyrolysis temperature increased from 400℃to 800℃.Besides,the calorific value of chars ranged from 11.18 to 15.62 MJ·kg^(-1).In addition,the concentration of heavy metals in char decreased with the increase of pyrolysis temperature.Particularly Pb can be enriched in chars obtained at 400℃~600℃,while most of Zn and Cd entered the gas phase.XRD analysis showed that the metals in the char mainly existed in the form of Pb3O4,Zn(OH)2 and Cd(OH)2,and a small amount of metal elements were also present.