Sulfidation of Zero-Valent Iron by Direct Reaction with Elemental Sulfur in Water: Efficiencies, Mechanism, and Dechlorination of Trichloroethylene
| Autor: | Bo Chen, Jiamei Li, Paul G. Tratnyek, Xiaojiang Qiu, Feng He, Shichao Cai |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Zerovalent iron
Trichloroethylene Iron Inorganic chemistry Sulfidation chemistry.chemical_element Water General Chemistry 010501 environmental sciences 01 natural sciences Sulfur chemistry.chemical_compound Reaction rate constant chemistry Environmental Chemistry Reactivity (chemistry) Water treatment Selectivity Water Pollutants Chemical 0105 earth and related environmental sciences |
| Zdroj: | Environmental sciencetechnology. 55(1) |
| ISSN: | 1520-5851 |
| Popis: | Sulfidation can enhance both the reactivity and selectivity (i.e., electron efficiency, ee) of zero-valent iron (ZVI) in contaminant removal, which may make this technology cost-effective for a wider range of water treatment applications. However, current sulfidation methods involve either hazardous or unstable sulfidation agents (e.g., Na2S, Na2S2O3, and Na2S2O4) or energy-intensive preparations (e.g., mechanochemical sulfidation with elemental sulfur). In this study, we demonstrate that very efficient sulfidation of microscale ZVI (mZVI) can be achieved at all S/Fe molar ratios (∼100% sulfidation efficiency, es) simply by direct reaction between elemental sulfur (S0) and ZVI in an aqueous suspension at ambient temperature. In comparison, the es values obtained using Na2S, Na2S2O3, or Na2S2O4 as the sulfidation agents were only ∼23, ∼75, and ∼38%, respectively. The sulfidated mZVI produced using the new method reacts with trichloroethylene (TCE) with very high rates and electron efficiencies: rate constants and electron efficiencies were 800- and 79-fold higher than those of the unsulfidated mZVI. The enhanced performance of this material, together with the operational advantages of S0 for sulfidation (including safety, stability, and cost), may make it a desirable product for full-scale engineering applications. |
| Databáze: | OpenAIRE |
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