Abstract

BI, Wenlong et al. Degradation of methyl orange by the Fenton-like reaction of pyrite-activated hydrogen peroxide forming the Fe(lll)/Fe(ll) cycle. Water SA [online]. 2024, vol.50, n.2, pp.166-178. ISSN 1816-7950.  http://dx.doi.org/10.17159/wsa/2024.v50.i2.4078.

In this study, the typical azo dye methyl orange (MO) was degraded by pyrite (FeS₂) activated by hydrogen peroxide (H₂O₂). When [MO] = 0.1 mM, [FeSJ = 2.0 g/L and [H₂O₂] = 22 mM, 96.4% MO was removed in 120 min and the TOC removal rate was higher than 50%. HO* was the primary radical responsible for MO degradation, in addition, the acid condition promoted the degradation of MO in the FeS₂/H₂O₂ system. MO in tap water and river water was not effectively degraded, whereas acidification could weaken the inhibitory effect on the FeS₂/ H₂O₂ system to enable the degradation of MO in tap and river water. The OD₆₀₀ indicated that the solution was environmentally friendly after the reaction, and three degradation pathways of MO were discussed. In summary, Fe(ll) could be dissolved from FeS₂, which activated H₂O₂ to generate Fe(lll) and HO*. FeS₂ could reduce Fe(lll) into Fe(ll), thus realizing the Fe(lll)/(ll) cycle and efficiently activating H₂O₂ to degrade MO.

Keywords : pyrite; hydrogen peroxide; methyl orange; advanced oxidation processes.

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