Modulating the iron (hydr)oxides/sulfides by H₂O₂ for a high-performance sulfidated zero-valent iron

Area of Science:

• Environmental Science
• Materials Science
• Chemistry

Background:

• Sulfidation of zero-valent iron (SZVI) enhances reactivity for contaminant removal.
• ZVI surface composition critically impacts sulfidation efficiency.
• Oxidant pre-corrosion is a promising strategy to modify ZVI surfaces.

Purpose of the Study:

• To investigate the use of hydrogen peroxide (H2O2) for pre-corrosion of ZVI during sulfidation.
• To develop a high-performance sulfidized ZVI (SZVIH2O2) material.
• To elucidate the mechanism of H2O2 pre-corrosion in enhancing SZVI reactivity.

Main Methods:

• Pre-corrosion of ZVI using H2O2 prior to sulfidation.
• Characterization of the SZVIH2O2 surface structure and composition.
• Evaluation of Cr(VI) removal kinetics using SZVIH2O2.

Main Results:

• SZVIH2O2 exhibited a kinetic constant (kobs) for Cr(VI) removal 5.25 times higher than SZVI.
• H2O2 pre-corrosion reconfigured surface iron (hydr)oxides, forming beneficial FeOOH.
• SZVIH2O2 developed a protective multi-layer shell (Fe3O4 outer, FexSy inner) enhancing electron transfer and durability.

Conclusions:

• H2O2 pre-corrosion is an effective method to enhance SZVI reactivity and durability.
• The Fe3O4/FexSy shell on SZVIH2O2 facilitates efficient electron transfer and protects against oxidation.
• This study advances the understanding of interfacial modulation of ZVI for improved contaminant remediation.