Stabilization of heavy metals in mining soil using palygorskite loaded by nanoscale zero-valent iron

Palygorskite-loaded nanoscale zero-valent iron (PAL-nZVI) had been applied to stabilize the heavy metals in mining soil. The toxicity characteristic leaching procedure (TCLP) and CaCl2 extraction results showed that the bioavailability and leaching toxicity decreased significantly with the addition of PAL-nZVI. The stabilization effect tended to remain unchanged and keep equilibrium when the incubation period extended to 30 days. Especially for Cu and Ni, the stabilization efficiency both increased by more than 60% when the addition dosage of PAL-nZVI was 8%. PAL-nZVI had a better stability effect on heavy metals, especially for Zn and Ni. The application of PAL-nZVI could transform the speciation of heavy metals from labile fraction to stable fraction (the maximum residual percentage of Zn and Ni increased by 33.26 and 27.97%, respectively) when the addition dosage of PAL-nZVI was 8% at 30 incubation period. The potential ecological index of different soil treatments was also reduced with the increase in the PAL-nZVI dose. Add the PAL-nZVI to combine heavy metals contaminated soil reduced the accumulation of heavy metals in the plant dramatically. PAL-nZVI was a promising material that had a demonstrably positive impact on the remediation of soil contaminated by the heavy metals.