Sulfide modified nanoscale zerovalent iron (S-nZVI) has been widely employed to sequester heavy metals and to degrade toxic organic pollutants, however, its nucleation and growth process has been not fully understood. Here we studied these fundamental synthesis processes and examined how they are affected by reactor material and nanoparticle seeding. Syntheses monitoring experiments show that nucleation of incipient Fe0 nanoparticles determines the formation of nanoparticles since Fe0 crystal growth rate is too much faster nucleation rate due to the severe agglomeration of Fe0 nanoparticles. While the effect of reactor material is limited, we observed that nanoparticle seeding favors the nucleation process by lowing the free surface energy. Increased nanoparticulate SiO2 seeding resulted in formation of more Fe0 crystal due to increased potential to reduce crystalline green rust, an intermediate product. While the the final magnetic S-nZVI contains a lot of flake-like structure, spherical crystals were also observed. Nanoparticulate-SiO2 seeding of S-nZVI allowed for increased sulfidation, and hence, metal removal capacity without losing the magnetic property of the material.

Novel  magnetic sulfide modified nanoscale zerovalent iron with film-like structure for metal removal

251st National Meeting (2016)

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