Exchange-coupled α-Fe/Fe3O4 bi-magnetic nanoparticles with non-core/shell morphology formed by eutectoid decomposition of FeO nanoparticles

Cost-effective core@shell structured zero-valent iron nanoparticles @ magnetic (nZVI@Fe3O4) for Cr(vi) removal from aqueous solutions: preparation by disproportionation of Fe(ii)

“…The average crystalline size of α-Fe microcrystals calculated using Scherrer's formula described in the ESI† is 49 nm, which is similar to the already reported size of α-Fe microcrystals prepared by FeO disproportionation decomposition (53 nm). 27…”

“…2(b)), but the increase is very weak, indicating that α-Fe is not dispersed and precipitated in the matrix of Fe 3 O 4 , which is consistent with the result of nZVI@Fe 3 O 4 nanocomposites prepared by FeO decomposition. 27 Therefore, the nZVI@Fe 3 O 4 may have a core@shell structure, where Fe(0) is located at the core position, resulting in the failure of the Fe(0) photoelectron to escape. The HRTEM and the slower removal rates of the subsequent batch tests likewise confirm this.…”

“…The average crystalline size of a-Fe microcrystals calculated using Scherrer's formula described in the ESI † is 49 nm, which is similar to the already reported size of a-Fe microcrystals prepared by FeO disproportionation decomposition (53 nm). 27 Meanwhile, the calculated average size of Fe 3 O 4 microcrystals is 40 nm. It is worth mentioning that the sharp and narrow XRD diffraction peaks of a-Fe conrms the good crystallinity, unlike the nZVI prepared by liquid-phase reduction, whose cores oen contain iron with poor crystallinity.…”

“…24,25 Some studies have used the disproportionation reaction of Fe(II) to prepare Fe@Fe 3 O 4 composites, but these typically involve complicated precursors like calcite (FeO) and have not been widely used for contaminant removal applications. 26,27 In this study, we used a very inexpensive and simple procedure to get rid of the expensive and complicated reduction process. nZVI@Fe 3 O 4 was synthesized through a one-step process, using ferrous chloride precursors and allowing Fe(II) disproportionation to occur in hot concentrated lye.…”

“…24,25 Some studies have used the disproportionation reaction of Fe( ii ) to prepare Fe@Fe 3 O 4 composites, but these typically involve complicated precursors like calcite (FeO) and have not been widely used for contaminant removal applications. 26,27…”