Mechanisms of hydroxyl radical production from abiotic oxidation of pyrite under acidic conditions

Zhang, Peng; Yuan, Songhu; Liao, Peng

doi:10.1016/j.gca.2015.10.015

Cited by 223 publications

(100 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Therefore, the disappearance of H 2 O 2 in solution was likely due to a fast transformation into ROS, catalyzed by dissolved Fe 2+ , rather than by the cessation of the generation mechanism itself. This result is consistent with the continuous production of H 2 O 2 and OH · 232660 during pyrite dissolution. We hypothesize that as a result of the progressive acidification of the solution together with iron recycling by the Fenton reaction, the abiotic dissolution of pyrite microparticles can be considered as a natural and auto-catalytic Fenton reagent, useful to understanding long-term oxidation processes even in oxygen limited environments.…”

Section: Discussionsupporting

confidence: 89%

“…The mechanism of H 2 O 2 formation in anoxic conditions remains more controversial. Some studies have suggested that in absence of O 2 the formation of H 2 O 2 is driven by the oxidation of adsorbed H 2 O catalyzed by the pyrite surface4192426, whereas other studies have considered that this reaction is unlikely due to energetic considerations1525. A possible reconciliation comes from considering the presence of ≡Fe 3+ dangling bonds generated from the cleavage of S-S bonds.…”

Section: Discussionmentioning

confidence: 99%

“…The iron surface species formed cause a reduction in the band gap of the pyrite from 0.86 electron volts (eV) in the bulk to 0.55 eV on the surface34, catalyzing the dissociation of adsorbed oxygen (O 2 ) and water (H 2 O) molecules and leading to the formation of H 2 O 2 (equations 1,2,3,4)19252635:…”

mentioning

confidence: 99%

See 2 more Smart Citations

Quantifying Fenton reaction pathways driven by self-generated H2O2 on pyrite surfaces

Gil-Lozano

Dávila

Losa-Adams

et al. 2017

Sci Rep

View full text Add to dashboard Cite

Oxidation of pyrite (FeS2) plays a significant role in the redox cycling of iron and sulfur on Earth and is the primary cause of acid mine drainage (AMD). It has been established that this process involves multi-step electron-transfer reactions between surface defects and adsorbed O2 and H2O, releasing sulfoxy species (e.g., S2O32−, SO42−) and ferrous iron (Fe2+) to the solution and also producing intermediate by-products, such as hydrogen peroxide (H2O2) and other reactive oxygen species (ROS), however, our understanding of the kinetics of these transient species is still limited. We investigated the kinetics of H2O2 formation in aqueous suspensions of FeS2 microparticles by monitoring, in real time, the H2O2 and dissolved O2 concentration under oxic and anoxic conditions using amperometric microsensors. Additional spectroscopic and structural analyses were done to track the dependencies between the process of FeS2 dissolution and the degradation of H2O2 through the Fenton reaction. Based on our experimental results, we built a kinetic model which explains the observed trend of H2O2, showing that FeS2 dissolution can act as a natural Fenton reagent, influencing the oxidation of third-party species during the long term evolution of geochemical systems, even in oxygen-limited environments.

show abstract

Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Quantifying Fenton reaction pathways driven by self-generated H2O2 on pyrite surfaces

Gil-Lozano

Dávila

Losa-Adams

et al. 2017

Sci Rep

View full text Add to dashboard Cite

show abstract

“…The reason should be related to the degradation of ciprofloxacin in these two systems, besides surface adsorption. Both iron sulfide and magnetite have been reported to be capable for activating dissolved O 2 in water, which results in the production of hydroxyl radicals (·OH) that are highly reactive for oxidative degradation of organic compounds [42][43][44]. For validating such a guess, the removal of ciprofloxacin by FeS/Fe 3 O 4 or FeS/Fe 3 O 4 @BC500 alone was conducted under nitrogen atmosphere.…”

Section: Comparison Of Various Catalysis Systems For Removal Of Cipromentioning

confidence: 99%

Biochar-Supported FeS/Fe3O4 Composite for Catalyzed Fenton-Type Degradation of Ciprofloxacin

et al. 2019

View full text Add to dashboard Cite

The Fenton-type oxidation catalyzed by iron minerals is a cost-efficient and environment-friendly technology for the degradation of organic pollutants in water, but their catalytic activity needs to be enhanced. In this work, a novel biochar-supported composite containing both iron sulfide and iron oxide was prepared, and used for catalytic degradation of the antibiotic ciprofloxacin through Fenton-type reactions. Dispersion of FeS/Fe 3 O 4 nanoparticles was observed with scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). Formation of ferrous sulfide (FeS) and magnetite (Fe 3 O 4 ) in the composite was validated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Ciprofloxacin (initial concentration = 20 mg/L) was completely degraded within 45 min in the system catalyzed by this biochar-supported magnetic composite at a dosage of 1.0 g/L. Hydroxyl radicals (·OH) were proved to be the major reactive species contributing to the degradation reaction. The biochar increased the production of ·OH, but decreased the consumption of H 2 O 2 , and helped transform Fe 3+ into Fe 2+ , according to the comparison studies using the unsupported FeS/Fe 3 O 4 as the catalyst. All the three biochars prepared by pyrolysis at different temperatures (400, 500 and 600 • C) were capable for enhancing the reactivity of the iron compound catalyst.

show abstract

“…Pyrite is abundant in underground sediments and is widely distributed in the underground strata of rivers. Although pyrite is formed in an anoxic environment, it remains stable in an aerobic environment [10]. Pyrite has an important effect on the migration, transformation, and degradation of toxic and harmful substances.…”

Section: Introductionmentioning

confidence: 99%

Detoxification of Cylindrospermopsin by Pyrite in Water

et al. 2019

View full text Add to dashboard Cite

Cylindrospermopsin (CYN) is a cyanobacterial toxin released from eutrophic water. It persistently remains in the environment because its degradation under solar light is extremely low. In this study, pyrite, an abundant mineral, was investigated as a catalyst for decomposing and detoxifying CYN in water. A detailed examination of intermediates provided insights into the degradation pathway. Electron spin resonance spectra revealed that H2O2 and hydroxyl radicals (•OH) were generated at the pyrite surface while promoting the recycling of Fe(III) into Fe(II) during the degradation process. This degradation system could be uniquely efficient in the presence of relatively high levels of natural organic matter because the structure of the uracil ring is decomposed to detoxify CYN. This work confirms a new approach to selectively and effectively detoxifying CYN in water using an inexpensive, environmentally friendly, and bio-compatible mineral.

show abstract

Mechanisms of hydroxyl radical production from abiotic oxidation of pyrite under acidic conditions

Cited by 223 publications

References 54 publications

Quantifying Fenton reaction pathways driven by self-generated H2O2 on pyrite surfaces

Quantifying Fenton reaction pathways driven by self-generated H2O2 on pyrite surfaces

Biochar-Supported FeS/Fe3O4 Composite for Catalyzed Fenton-Type Degradation of Ciprofloxacin

Detoxification of Cylindrospermopsin by Pyrite in Water

Contact Info

Product

Resources

About