How does sulfur promote the conversion of zero valent iron valence states?
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Sulfur promotes the conversion of zero valent iron valence states through several mechanisms. Firstly, the presence of sulfur precursors, such as elemental sulfur (S0) or sulfur compounds, leads to the sulfidation of zero valent iron (ZVI), forming sulfidated ZVI (S-ZVI) . The sulfidation process increases the reactivity and selectivity of ZVI towards various contaminants, such as Cr(VI) and halogenated hydrocarbons . Sulfur species, such as FeS and iron polysulfides (FeSx), play a crucial role in the removal of contaminants by S-ZVI . Sulfur also depassivates the surface of ZVI, enhancing its reactivity and promoting sulfidation . Additionally, sulfur-modified iron, which incorporates sulfur into the ZVI structure, prevents the degradation of ZVI's chemical activity over time, making it more effective for remediation purposes . Overall, sulfur facilitates the conversion of ZVI valence states by promoting sulfidation, enhancing reactivity, and preventing deactivation of ZVI.
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Open access 01 Jul 2013 | Sulfur-modified iron provides sulfur, together with iron, to maintain stable sequestration of technetium. The paper does not explicitly mention how sulfur promotes the conversion of zero valent iron valence states. |
2 Citations | The paper does not provide information on how sulfur promotes the conversion of zero valent iron valence states. |
| The paper does not provide information on how sulfur promotes the conversion of zero valent iron valence states. | |
2 Citations | The provided paper does not directly address how sulfur promotes the conversion of zero valent iron valence states. |
| The paper does not provide information on how sulfur promotes the conversion of zero valent iron valence states. |
Related Questions
How does S2- react with Fe2 in the liquid phase as Fe0?10 answersThe interaction between S2- and Fe2 in the liquid phase, particularly when Fe is in its zero-valent state (Fe0), involves complex chemical dynamics that can be elucidated through insights from various research findings. The reactivity of sulfur species towards iron, especially in the context of iron sulfides formation, provides a foundational understanding of these interactions. For instance, the colloidal synthesis of iron sulfides demonstrates that the reactivity of sulfur sources, including diatomic sulfur (S2), significantly influences the phase of iron sulfides formed, such as pyrite (FeS2), greigite (Fe3S4), and pyrrhotite (Fe7S8). This suggests that the presence of S2- in the liquid phase can lead to the formation of various iron sulfide species depending on the conditions.
Moreover, the electrochemical behavior of FeS2, as studied through cyclic voltammetry, reveals insights into the surface reactivity and the potential for phase transformations under different pH conditions, which could be reflective of the interactions between S2- and Fe2 in solution. The generation of diatomic sulfur (S2) from stable 1,2-dithietane derivatives further underscores the potential for S2- to participate in reactions leading to the formation of iron sulfides.
Analytical methods for monitoring Fe2+ concentration during liquid-phase sulfite oxidation catalyzed by iron ions highlight the intricate balance between Fe2+ and Fe3+ in solution, which could be influenced by the presence of S2- through redox reactions. Additionally, the study of Fe-S-O system phase equilibrium and oxygen partial pressure provides a thermodynamic perspective on the conditions under which S2- might react with Fe2 in the liquid phase to form various iron and sulfur compounds.
Density functional theory (DFT) calculations on the structures and energies of different iron-sulfur clusters, including Fe2S2 and FeS, offer a molecular-level understanding of the potential reaction pathways and the stability of the resulting compounds. This theoretical framework supports the experimental observations of iron sulfide particle formation using different sulfur sources and synthesis methods, which indirectly relate to the behavior of S2- in reacting with Fe2 in the liquid phase.
In summary, the reaction of S2- with Fe2 in the liquid phase as Fe0 involves a complex interplay of chemical reactions leading to the formation of various iron sulfide phases. This process is influenced by factors such as the sulfur source reactivity, electrochemical conditions, redox state of iron, and thermodynamic stability of the resulting compounds.
How does fe2 react with s2- to form zero valent iron?5 answersFe2 reacts with S2- to form zero-valent iron sulfide (SZVI) through a sulfidation process. The formation of SZVI involves the in situ generation of iron sulfide (FeSx) on the surface of zero-valent iron (ZVI). This chemical bonding between FeSx and ZVI enhances electron transportation efficiency, leading to improved performance in reducing contaminants like Cr(VI). Additionally, the reactivity and selectivity of sulfidized nanoscale zerovalent iron (SNZVI) are influenced by the type of sulfur species present in the material, with different sulfur precursors resulting in varied physicochemical properties and reactivity towards pollutants like trichloroethene (TCE). The use of elemental sulfur (S0) directly reacting with ZVI at ambient temperature achieves highly efficient sulfidation, enhancing the reactivity and electron efficiency of the material for contaminant removal.
Can sulfurized nano iron be used as a catalyst for the nitrogen reaction?5 answersSulfurized nano iron has been investigated as a catalyst for the nitrogen reduction reaction. FeS2 nanocrystals grown on carbon fiber paper (FeS2/CFP) have been found to be an electrochemical and photoactive catalyst for nitrogen reduction under ambient conditions. The electrochemical results showed that FeS2/CFP achieved a high Faradaic efficiency and ammonia yield rate. Additionally, iron pyrite-based materials, such as FeS2, have been shown to have strong chemical adsorption energy for N2 molecules, making them potential electrocatalysts for ammonia production. However, there is no specific mention of "sulfurized nano iron" as a catalyst for the nitrogen reaction in the other abstracts provided.
Does sulfur assimilation influence Cysteine and Glutathione levels?4 answersSulfur assimilation does influence cysteine and glutathione levels. Transgenic tobacco and Arabidopsis plants overexpressing the cytosolic AtGR1 and plastidic AtGR2 genes had higher levels of cysteine and glutathione. Sulfur is an essential element for plants, and they utilize soil sulfate to synthesize cysteine, which is used for the production of glutathione and other sulfur-containing compounds. The activity of adenosine 5' phosphosulfate reductase (APR), a key enzyme in the sulfur assimilation pathway, is supported by glutathione reductase (GR). The expression of sulfur transport and assimilatory genes, including SULTR and APR, is increased by treatment with 5-aminolevulinic acid (ALA), a precursor of porphyrin biosynthesis. Sulfate assimilation and glutathione synthesis are not differentially compartmentalized in all C4 plants, with enzymes of glutathione biosynthesis being active in both bundle sheath and mesophyll cells.
What are the mechanisms by which Sulfur promotes the conversion of Fe valence states?5 answersSulfur promotes the conversion of Fe valence states through various mechanisms. In higher alkali solutions, soluble divalent iron sulfur complexes are formed involving S22- ions, leading to the passivation of iron. The presence of sulfur enhances the reduction of trivalent oxides to soluble divalent iron, facilitating passivation by forming a polysulfide film. Additionally, sulfur in the gas phase, along with calcium in the oxide, can cause catastrophic swelling through iron whisker growth during the reduction of solid calciowustites. In the context of Li-S batteries, Fe3C and metallic Fe in Fe-N-C sulfur hosts play key roles in modulating polysulfide conversion. Fe3C strongly adsorbs polysulfide, while Fe particles catalyze fast polysulfide conversion, resulting in nearly complete conversion of polysulfides and high battery performance. These mechanisms highlight the influence of sulfur on the conversion of Fe valence states in different systems.
How does ZnS react with hot sulfuric acid?5 answersZnS reacts with hot sulfuric acid by undergoing anodic dissolution, resulting in the formation of Zn2+ and S as products. The majority of the research on this reaction has been conducted in H2SO4, although limited tests have been made in HCl and KOH. Polarization studies have shown that ZnS passivates in KOH solutions. The overall dissolution of ZnS in sulfuric acid appears to be mass transfer-limited, possibly due to the diffusion of Zn2+ from the reaction interface through the reacted layer to the bulk solution. The concentrate anodes made from ZnS polarize more drastically than reagent grade ZnS anodes, possibly due to the presence of PbS impurity in the concentrate, which forms PbSO4 in the anode pores.