Immobilization of Zn and Pb in Polluted Soil by In Situ Crystallization Zeolites from Fly Ash

In the last few years, a great deal of research on soil has been carried out in order to develop a low-cost remediation method for reducing the environmental risks due to the pollution caused by heavy metals. In the light of this, the zeolitization achieved in soils mixed with coal fly ash could be a useful answer to reduce the amount and the mobility of metals in polluted areas. In this study, a selected soil treated with coal fly ash and artificially contaminated with Zn or Pb was used to synthesize zeolite at low temperature in laboratory and on a bench-scale experiments. Mineralogical data showed that the synthesis of zeolite X took place readily after the first month, and the amount of the newly formed mineral increased during the entire 1-year-long incubation period. The presence of toxic elements does not interfere with zeolite crystallization, whereas the chemical analysis indicated that a reduction in heavy metal availability takes place in the samples characterized by the presence of zeolite.