Several bench- and pilot-scale studies have demonstrated the effectiveness of nanoscale zero-valent iron (nZVI) and sulfidated nZVI (SnZVI) in remediation of organic compounds in groundwater. However, the application and ecological impact of nZVI and SnZVI in soil are less investigated. In this study, 0.3 to 5% of nZVI and SnZVI were applied to 50 ppm arsenic-contaminated soil. The As immobilization performance of both nanoparticles, and their impact on earthworm (Eisenia fetida) were assessed simultaneously. Arsenic immobilization efficiencies reached 93% and 68% after 7 d when contaminated soil was treated with 0.3 % nZVI and SnZVI, respectively. The higher nanoparticle dosages and longer treatment time resulted in higher arsenic immobilization. SnZVI performed better than nZVI when the immobilized arsenic was normalized by the surface area of both nanoparticles. Additionally, artificial neural network (ANN) was used to simulate arsenic immobilization efficiency with three input variables (nanoparticle dosage, nanoparticle type, and treatment time). Sulfidation of nZVI increased the survival of E. fetida from 10% when contaminated soil was treated with 0.3% nZVI and 60% when contaminated soil was not untreated to 73% (when treated with 0.3% SnZVI) after 28 days. Arsenic bioaccumulation in surviving E. fetida also decreased when soil was treated with both nanoparticles. This study demonstrates that sulfidation could decrease the environmental impact of nZVI-based nanoremediation without compromising the effectiveness of the technology.

Effect of sulfidation on the application and ecotoxicity of nanoscale zero-valent iron in soil

ACS Fall 2021

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