Sulfidation of zerovalent iron for improving the selectivity toward Cr(VI) in oxic water: Involvements of FeSx

Interaction of pyrite with zerovalent iron with superior reductive abilityviaFe(ii) regeneration

“…The FeS x layer exhibits a favorable affinity for anions to facilitate the concentration of Cr(VI) anions on the FeS 2 /ZVI surface and favors the electron transfer from Fe 0 to Cr(VI) at the surface as an efficient electron conductor. 21,55 To better illustrate the structure properties of Fe in FeS 2 / ZVI, a Mössbauer analysis has been conducted. Mössbauer spectroscopy has developed into an important tool for the study of material structure and its changes, especially for the Environmental Science: Nano Paper Fe cycling and environmental behavior of metallic elements, due to the possibility of determining Fe phases and contents independent of size and crystallinity.…”

“…In contrast, the Q e of FeS 2 /ZVI increased by 4.4 times to 52.08 mg g −1 (Table S2 †), which was much higher than those of most reported SZVI materials. 21,24,25,29,[64][65][66][67] ZVI-based materials generally exhibit strong pH dependence. 14,45,68 Acidic conditions favor the Cr(VI) removal by an iron-mediated system, which involves a protonconsuming process.…”

“…[17][18][19][20] Li et al found that sulfidation significantly improved the electron selectivity of ZVI towards Cr(VI) over water and contributed to the formation of FeS x . 21 Kim et al demonstrated that the dechlorination rate of trichloroethylene (TCE) on SZVI increased by 40 times as compared with ZVI. 22 However, SZVI still suffers from the relatively weak regeneration ability of Fe(II), [23][24][25] which is the major electron donor for reductive removal of pollutants by SZVI.…”

“…[31][32][33][34] But both the dense base layer of FeS x and precipitation of secondary FeS x were unfavorable for the corrosion rate of the underlying Fe 0 core. 21,25,33,35 The regeneration of Fe(II) is strongly inhibited by the surface FeS x layer from SZVI. 21 Moreover, the narrow applicable pH range (only acidic conditions) limits its practical application.…”

“…21,25,33,35 The regeneration of Fe(II) is strongly inhibited by the surface FeS x layer from SZVI. 21 Moreover, the narrow applicable pH range (only acidic conditions) limits its practical application. When the pH is above 5.00, the electron transfer from ZVI to the target contaminant and the release of Fe(II) would be inhibited due to the deposition of iron (hydr)oxides.…”