Zero-valent iron nanoparticles (nZVI) have been widely used in waste treatment and for in-situ remediation. The iron nanoparticles have a classical core-shell structure in which a metallic iron core is enclosed by a thin layer of iron oxides/hydroxides. The two nano-components offer synergistic functions for high-efficiency separation, enrichment and stabilization of heavy metal such as Au, Ag, Cu, Ni, U and As. Thanks to the advantages of small size, large surface and high reactivity, only a small amount of the iron nanoparticles are needed. The recovered nanoparticles could contain high-levels of precious metals. Large-scale applications in China have demonstrated that recovery of precious metals from trace-level sources such as wastewater is economically practicable. In this presentation, we report the application of spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM) for atomic (~0.1 nm) resolution imaging of reactions in a single nZVI nanoparticle.<sup> </sup>Integrated with analytical approaches such as XEDS and EELS, Cs-STEM system can provide directly evidence on both nanoparticle morphology and element compositions. Furthermore, with this technique, three-dimensional (3D) perspectives offer unique knowledge about the heavy metal-nZVI reactions. Pilot and full-scale applications applying nZVI for treatment of a metal smelting effluent containing concentrated heavy metals (&gt;100 ppm) and arsenic (&gt;200 ppm) will also be presented.

Reactions of nanoscale zero-valent iron (nZVI) with heavy metals: 3D visualization

255th National Meeting (2018)

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