Hydrogen Peroxide Decomposition by Pyrite in the Presence of Fe(III)-ligands

P. Chirită

Abstract
The decomposition of hydrogen peroxide (H2O2) by pyrite in the presence of Fe(III)-ligands (sulfosalicylate (SSAL), ethylenediaminetetraacetate (EDTA), and phosphate) has been investigated in aqueous acidic media (pH 1) at 25 °C. It was found that H2O2 decomposition by pyrite was inhibited by the presence of EDTA, SSAL and phosphate. On the other hand, pyrite oxidation by H2O2 does not seem to be affected by the presence of Fe(III)-ligands. The experimental results demonstrate that H2O2 decomposition in the presence of Fe(III)-ligands is catalyzed by pyrite surface (a heterogeneous process). This process is first order with respect to [H2O2]. It is expected that the rate-determining step of the reaction mechanism of H2O2 decomposition in the presence of Fe(III)-ligands is one of the following two reactions: ≡FeHO2 2+→ ≡Fe2+ + HO2 • ≡Fe(OH)(HO2)+→ ≡Fe2+ + HO2• + HO– where ≡ denotes pyrite surface.

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Keywords
hydrogen peroxide, pyrite, Fe(III)-ligands, reaction mechanism