Mechanism of Increased Retention of Atomic Hydrogen on Moderately Sulfidated Zero-Valent Iron Surfaces
Sulfidation represents a promising approach to increase the reactivity, selectivity, and longevity of zero-valent iron (ZVI) in groundwater remediation applications. Recent studies suggest that reductive reactions mediated via adsorbed H* may dominate the degradation of prominent contaminants, such...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1985. - 41(2025), 41 vom: 21. Okt., Seite 28193-28206 |
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| Format: | Online-Aufsatz |
| Sprache: | English |
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2025
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article |
| Zusammenfassung: | Sulfidation represents a promising approach to increase the reactivity, selectivity, and longevity of zero-valent iron (ZVI) in groundwater remediation applications. Recent studies suggest that reductive reactions mediated via adsorbed H* may dominate the degradation of prominent contaminants, such as chlorinated ethenes, on sulfidated ZVI (S-ZVI) surfaces with moderate S coverage, challenging the initially proposed major role of direct electron transfer. This study employs density functional theory to investigate how S coverage and surface corrosion influence H* formation, stability, mobility, and recombination at S-ZVI surfaces at atomic resolution. Our calculations reveal that sulfidation suppresses water adsorption and H* formation via water dissociation, while also weakening H* adsorption affinity on ZVI. However, as surface oxidation also hinders H* adsorption and promotes H* recombination, S-ZVI with moderate (∼14 monolayer) S coverage retains more reduced Fe sites, which are favorable for H* adsorption, compared to the corroded ZVI surface. Adsorbed H* at the reduced Fe sites exhibits restricted mobility near S atoms, limiting H* recombination and increasing its availability for contaminant degradation. These findings provide a fundamental mechanistic understanding of increased H* retention at S-ZVI surfaces with moderate S coverage, with implications for the role of H*-mediated reactions in these systems |
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| Beschreibung: | Date Revised 21.10.2025 published: Print-Electronic Citation Status PubMed-not-MEDLINE |
| ISSN: | 1520-5827 |
| DOI: | 10.1021/acs.langmuir.5c04136 |