Synthesized and Commercial Iron Sulfide Particles as Contaminant Sorbents

Herein, the nanoparticles of iron sulfide, nominally greigite (Fe3S4) but including other iron sulfides (pyrite and pyrrhotite), are investigated for the targeted removal of contaminants from aqueous solutions simulating radioactive liquid waste. The target radioisotopes, for example, Tc and I, are highly mobile in groundwater at contaminated sites, and their half-lives drive long-term environmental doses for some radioactive waste disposal sites. Thus, it is advantageous to separate them from liquid streams and sequester them elsewhere. Greigite particles were synthesized by: 1) mechanosynthesis; 2) hydrothermal; and 3) solvothermal routes and compared to commercially available Fe-S particles. The phase assemblages of the produced iron sulfides were examined via X-ray diffraction (XRD), particle morphologies via scanning electron microscopy (SEM), and magnetic properties via vibrating sample magnetometry (VSM). Hydrothermally synthesized material was closest to single-phase greigite and so was utilized to demonstrate the removal of Re (a surrogate for Tc) from an aqueous solution, as monitored by Raman spectroscopy. Fe-S particles such as these show promise for use as radionuclide sorbents for use in magnetic separation flowsheets.