Remediation of Cd and Zn contaminated soil by zero valent iron (Fe0): A field trial

Remediation of contaminated soil is a long-term challenge faced by human beings. The in-situ remediation was carried out using zero valent iron (Fe0) with the rotation pattern of soybean–rape the near a smelter influenced by atmospheric subsidence. The results showed that the total contents of Cd and Zn in rhizosphere soils with Fe0 treatment were lower than that in the control. The biomass of soybean and rape increased by 55.4 ∼64.9% and 6.2 ∼42.8%, respectively with the addition of Fe0. And Fe0 decreased the availability of Cd and Zn and the accumulation of Cd and Zn in plant roots. The Cd and Zn contents of the iron-rich substances separated from soil were much high, reaching 155.8 mg/kg and 29525 mg/kg, respectively and the total Cd and Zn in the remaining soil decreased by 28.5% and 44.6%, respectively. XRD and XPS analysis of the separated substance implied that the new production of iron oxides (γ-FeOOH and γ-Fe2O). The existence of CdO and CdS were observed and the main forms of Zn were ZnS, ZnO and ZnCO 3 through the immobilization of iron oxides. This work suggested the feasibility of Fe0 in the contaminated soil. Using retrievable materials from soil to remove permanently pollutants should be considered in the future remediation practice.