Nanoscale Zero Valent Iron (nZVI) can be protected from rapid oxidation by various methods including the use of organic or inorganic molecules. A simple oxide layer allows long-term storage of nZVI on contact with air, as well as safe delivery and simple manipulation. On the other hand, the protection is so good that simple dilution in water cannot deactivate the protective layer and the nanoparticles must be activated prior to their application. The activation process involves preparing concentrated nZVI/water slurry (20% wt.) and leaving it for 48 hours. In the present research, three types of particles with different oxide shell thicknesses were compared in order to assess their reactivity with Cr(VI) as a representative contaminant. The results showed a diminution in the reduction capacity of Cr(VI) with increasing shell thickness. The activation process was able to create irregularities in the protective oxide shell with a thickness of <3.4 nm and to significantly improve Cr(VI) reduction.Keywords: nZVI, nanoiron, reductive processes, remediation
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