Iron Nanoparticles:  the Core−Shell Structure and Unique Properties for Ni(II) Sequestration

Abstract

It is demonstrated that iron nanoparticles function as a sorbent and a reductant for the sequestration of Ni(II) in water. A relatively high capacity of nickel removal is observed (0.13 g Ni/g Fe, or 4.43 mequiv Ni(II)/g), which is over 100% higher than the best inorganic sorbents available. High-resolution X-ray photoelectron spectroscopy (HR-XPS) confirms that the zerovalent iron nanoparticles have a core-shell structure and exhibit characteristics of both hydrous iron oxides (i.e., as a sorbent) and metallic iron (i.e., as a reductant). Ni(II) quickly forms a surface complex and is then reduced to metallic nickel on the nanoparticle surface. The dual properties of iron nanoparticles may offer efficient and unique solutions for the separation and transformation of metal ions and other environmental contaminants.

A radiotracer study of the adsorption behavior of aqueous Ba2+ ions on nanoparticles of zero-valent iron

“…These nanoparticles are seen to form chain-like aggregates, demonstrating a morphology that resembles the previously reported ones (e.g. [11,15,16]). …”

“…Comparatively, less effort was devoted to studying the adsorption of metal ions on NZVI. The ions investigated so far include As(III) and As(V) [7][8][9], Pb(II) [3], Cr(VI) [10], Ni(II) [11], and other ions [12]. No reports are present on the applicability of NZVI for radioactive isotopes which are important from radioactive waste management viewpoint.…”

Arsenate removal with 3-mercaptopropanoic acid-coated superparamagnetic iron oxide nanoparticles

“…SPION functionalization provides a more active adsorption sites accessible to both arsenite and arsenate. The most important reason for the observed increase of is the decrease of SPION aggregation by a dispersion that leads to a higher availability of adsorption positions [10,[44][45][46][47][48][49][50][51].…”

Effects of nitrate on the treatment of lead contaminated groundwater by nanoscale zerovalent iron

“…Nitrate concentrations as high as 300 mg/L have been detected in groundwater [2].nZVI is easily oxidized on exposure to water, hence the Fe(0) core is surrounded by an oxide layer [6,29]. The core-shell structure is key for Pb 2+ sequestration (partly reduction by core but mainly adsorption and co-precipitation on shell) [15,29,30], but this unique structure is destroyed during the nitrate reduction process as Fe(0) may be oxidized completely [19]. The potential effect of the damaged structure on the ability of nZVI to immobilize Pb 2+ has not been investigated to date.…”