Enhanced oxidation resistance of NaBH4-treated mackinawite (FeS): Application to Cr(VI) and As(III) removal

Aqueous Adsorption of Heavy Metals on Metal Sulfide Nanomaterials: Synthesis and Application

“…For removing HMs from aqueous media, the essential MSs include sulfides of transition metals such as zinc [14,15], copper [31,32], cobalt [21,22], iron [33][34][35], and cadmium [14,36,37]. MSs contain localized or migratory sulfide 3d electrons or both, exhibiting hybridization with sulfide 3s and 3p orbitals, stabilizing the closest cation neighbors in the trigonal pyramidal, octahedral, tetrahedral, and other configurations in the anion arrays [30,38].…”

“…These configurations facilitate the formation of metal-metal and sulfur-sulfur covalent bonds. The increased covalency and polarization may support layered sheet structures with Van der Waals forces between the sheets [3,34,39]. The atomic arrangements in MSs are usually close-packing combinations, governed by ionic size, charge, and electron configuration [30,40].…”

“…However, one primary function of supports for MS-NMs is giving the core material stability in the air. Many MSs, especially FeS, are easily oxidized in the air and consequently require support to limit or prevent the oxidation [34,80,81]. Another critical reason for the use of a support for some nanoparticles of MSs is that they agglomerate rapidly in water, thereby having limited interaction with the targeted HMs [82][83][84].…”

“…The addition of magnetic support to MS-NMs to aid in the easy separation of adsorbent from water may be cost-intensive for largescale applications. Additionally, the support may interfere with the adsorption process, limiting removal efficiency [34].…”

“…Various support materials (or stabilizers) have been used to modify the surface of FeS nanoparticles (NPs) to limit inherent shortcomings and to improve their adsorption properties in removing HMs from aqueous solutions (Figure 5A,B and Table 2). The supporting materials used for FeS include biochar [87], plant extract [81], NaBH 4 [34], and others to reduce particle agglomeration and oxidation and increase recovery efficiency. However, some supports may reduce the removal efficiency of the adsorbent [34]; therefore, suitable materials that do not adversely affect adsorption efficiency are required.…”