pH Dependence of Fenton Reagent Generation and As(III) Oxidation and Removal by Corrosion of Zero Valent Iron in Aerated Water
- 30 August 2008
- journal article
- research article
- Published by American Chemical Society (ACS) in Environmental Science & Technology
- Vol. 42 (19), 7424-7430
- https://doi.org/10.1021/es800649p
Abstract
Corrosion of zerovalent iron (ZVI) in oxygen-containing water produces reactive intermediates that can oxidize various organic and inorganic compounds. We investigated the kinetics and mechanism of Fenton reagent generation and As(III) oxidation and removal by ZVI (0.1m2/g) from pH 3−11 in aerated water. Observed half-lives for the oxidation of initially 500 μg/L As(III) by 150 mg Fe(0)/L were 26−80 min at pH 3−9. At pH 11, no As(III) oxidation was observed during the first two hours. Dissolved Fe(II) reached 325, 140, and 6 μM at pH 3, 5, and 7. H2O2 concentrations peaked within 10 min at 1.2, 0.4, and 2 and H2O2 and inhibited As(III) oxidation. 2-propanol (14 mM), scavenging OH-radicals, quenched the As(III) oxidation at pH 3, but had almost no effect at pH 5 and 7. Experimental data and kinetic modeling suggest that As(III) was oxidized mainly in solution by the Fenton reaction and removed by sorption on newly formed hydrous ferric oxides. OH-radials are the main oxidant for As(III) at low pH, whereas a more selective oxidant oxidizes As(III) at circumneutral pH.Keywords
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