Reduction and Immobilization of Movable Cu2+ Ions in Soils by Fe78Si9B13 Amorphous Alloy

Abstract

The Fe-based amorphous alloy (Fe78Si9B13AP) is applied to the remediation of copper contaminated soil for the first time. The dynamic process of conversion of movable Cu to immobilized forms in the soil system is analyzed. In addition, the dynamic process of form transformation of Cu2+ ions in the soil system is analyzed. The morphology and phase composition of the reaction products are characterized by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Finally, the feasibility of recovering residual stabilizer particles and attached immobilized copper by the magnetic separation process is discussed. The results show that the apparent reaction rate constant of Fe79Si9B13AP with Cu2+ ions is higher than that of zero valent iron (ZVI) at all the experimental temperatures. According to the Arrhenius formula, the apparent activation energy of the reaction of Fe78Si9B13AP and ZVI with Cu2+ ions is 13.24 and 19.02 kJ/mol, respectively, which is controlled by the diffusion process. The lower apparent activation energy is one of the important reasons for the high reaction activity of Fe78Si9B13AP. After 7 days of reaction, a continuous extraction of the experimental soil shows that the main form of copper in the immobilized soil is Cu and copper combined with iron (hydroxide) oxide, and there is almost no soluble copper with a strong mobility, which effectively reduced the bioavailability of copper in the soil. The magnetic separation results of the treated soil show that the recovery rates of immobilized copper in Fe78Si9B13AP and soil are 47.23% and 21.56%, respectively, which reduced the content of iron and copper in the soil to a certain extent. The above experimental results show that Fe78Si9B13AP is a promising new material for the remediation of heavy metal contaminated soils, and provides more new references for the application of amorphous alloys in the field of remediation of water and soil contaminated by heavy metals and organic matter.