Reagent or catalyst? – FeS as activator for persulfate in water
| Autor: | Sarah Sühnholz, Frank-Dieter Kopinke, Katrin Mackenzie |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
chemistry.chemical_classification
Sulfide General Chemical Engineering Inorganic chemistry chemistry.chemical_element 02 engineering and technology General Chemistry Activation energy 010402 general chemistry 021001 nanoscience & nanotechnology Persulfate 01 natural sciences Sulfur Industrial and Manufacturing Engineering 0104 chemical sciences Catalysis Homolysis chemistry.chemical_compound chemistry Reagent Peroxydisulfate Environmental Chemistry 0210 nano-technology |
| Zdroj: | Chemical Engineering Journal. 387:123804 |
| ISSN: | 1385-8947 |
| DOI: | 10.1016/j.cej.2019.123804 |
| Popis: | FeS was evaluated as heterogeneous activator for peroxydisulfate (PS) with trichloroethene (TCE) chosen as model substance representing organic water pollutants prone to fast oxidation by sulfate radicals. The TCE degradation followed in most cases pseudo-first-order kinetics with a FeS-normalized maximum rate constant of k’TCE = 140 M−1min−1 (with cFeS,0 = 0.28 mM and cPS,0 = 5 mM). Sulfate radicals were determined as predominant radical species formed during PS activation by FeS by evaluation of the kinetic isotope effect for oxidation of cyclohexanes C6H12 vs. C6D12 (kC6H12: kC6D12 = 2.22). Monitoring of sulfur and iron species during the course of the reaction revealed that sulfide is rapidly oxidized, whereas Fe(II)solid is rather stable over time. The present study describes in detail the influence of the pH value on the reaction and the long-term performance of FeS as activator for PS with an optimum pH value of 5. On the basis of the radical yield from PS of 1.6 mols SO4− per mol S2O82− and the activation energy of EA = (31 ± 1) kJ mol−1 for the heterogeneous radical generation, a surface-assisted homolytic bond cleavage without simultaneous electron transfer is proposed as activation mechanism, which is contrary to the currently prevailing opinion. |
| Databáze: | OpenAIRE |
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