The Study On Heavy Metals Washing Of Contaminated Soil In Electronic-waste

Guangdong province is one of the most serious e-waste polluted city. Along with theadvance of industrial transfer and upgrade, there have a large number of heavy metalscontaminated sites which needed to be remediated around the small workshops. The sitesshow the characteristics that many high concentration heavy metals exist at the same time.Due to the advantages of simple operation, good controllability, remediation speed andmoderate conditions, washing is under a great attentioninsoil remediation.In this thesis, the simulation polluted and practical polluted soil washed by SDS, SDBS,TX-100, Tween-80, EDTA, citric acid, saponin and cyclodextrin. Results show that citric acidis the one of the economical and efficient eluant. The Influencing factors of washing is alsobeen studied.The results show the concentration of simulation soil is Cu5028.34mg/kg, Pb2288.70mg/kg, Cd47.23mg/kg, while the practical soil is Cu4169.69mg/kg Pb1360.57mg/kg, Cd29.00mg/kg.The acetic acid extractable fraction (R1) and the reductivefraction (R2) are the mainly soil fractions in two kinds of soils. The proportion between themin simulation soil is Cu87%Pb78%Cd90%, while in practical soil is Cu83%Pb88%Cd93%.The removal rate of Cu, Pb and Cd was89.37%,72.11%and86.39%respectively whencitric acid concentration was0.1mol/L, pH was5and shaking time was24hours insimulation soil, while Cu66.98%Pb55.33%Cd83.61%in practical soil. The BCRprocedure showed that the acetic acid extractable fraction (R1) and the reductive fraction (R2)of Cu, Pb and Cd are the mainly soil fractions which is been washed out. And it is beyond90%of total washing removal amount.It has no effection on the removal rate that the concentration of potassium ion and theaging time changing. The removal rate of the used citric acid which is dealed with sodiumsulfide on Cu, Pb, Cd is58.76%35.97%8.95%respectively.The fitting degree of the four models are poorly on the reaction between citric acid andCu, Cd. While the the reaction between citric acid and Pb can be described by the first-orderkinetic equation.