Mechanisms for hydroxyl radical production and arsenic removal in sulfur-vacancy greigite (Fe3S4)

Abstract

Herein, we systematically investigated the mechanisms of Å OH production and arsenic (As(III)) oxidation induced by sulfur vacancy greigite (Fe 3 S 4 ) under anoxic and oxic conditions. Reactive oxygen species analyses revealed that sulfur vacancy-rich Fe 3 S 4 (SV-rich Fe 3 S 4 ) activated molecular oxygen to produce hydrogen peroxide (H 2 O 2 ) via a two-electron reduction pathway under oxic conditions. Subsequently, H 2 O 2 was decomposed to Å OH via the Fenton reaction. Additionally, H 2 O was directly oxidized to Å OH by surface high-valent iron (Fe(IV)) resulting from the abundance of sulfur vacancies in Fe 3 S 4 under anoxic/oxic conditions. These differential Å OH-generating mechanisms of Fe 3 S 4 resulted in higher Å OH production of SV-rich Fe 3 S 4 compared to sulfur vacancy-poor Fe 3 S 4 (SV-poor Fe 3 S 4 ). Moreover, the Å OH production rate of SV-rich Fe 3 S 4 under oxic conditions (19.3 ± 1.0 lMh À1 ) was 1.6 times greater than under anoxic conditions (11.8 ± 0.4 lMh À1 ). As(III) removal experiments and X-ray photoelectron spectra (XPS) showed that both Å OH production pathways were favorable for As(III) oxidation, and a higher concentration of As(V) was immobilized on the surface of SV-rich Fe 3 S 4 under oxic conditions. This study provides new insights concerning Å OH production and environmental pollutants removal mechanisms on surface defects of Fe 3 S 4 under anoxic and oxic conditions.

A potential link between the structure of iron catalysts and Fenton-like performance: from fundamental understanding to engineering design

“…As some studies reported the concentration of sulfur vacancies in Fe 3 S 4 can be adjusted by altering the ratio of ethylene glycol to water during the synthesis process. 80,162…”

TiO2 Quantum Dots/Fe3S4 Heterojunction Nanocomposites for Efficient Ammonia Production through Nitrogen Fixation upon Simulated Sunlight

“…Furthermore, it has been found that by controlling the size of particles and reducing the sizes below 10 nm, the resultant TiO 2 quantum dots (TiO 2 QDs) presented outstanding photocatalytic performance due to improving textural properties, efficacious charge segregation, and changing redox potentials. , Greigite (Fe 3 S 4 ) is an iron–sulfur spinel with a crystalline structure, which is widely used in carbon dioxide reduction, nitrogen fixation, and environmental purification by removing heavy metals due to its ferromagnetic, environmentally friendly, cost-effective, and reducing properties. Furthermore, due to having a small energy gap, it can be simply excited by the sunlight illumination. , Greigite has abundant active sites due to the higher relative content of S 2– , Fe 3+ , and Fe 2+ on the surface, which leads to boosted photocatalytic performance …”

“…Furthermore, due to having a small energy gap, it can be simply excited by the sunlight illumination. 17,18 Greigite has abundant active sites due to the higher relative content of S 2− , Fe 3+ , and Fe 2+ on the surface, which leads to boosted photocatalytic performance. 19 In this paper, we prepared S-scheme TiO 2 QDs/Fe 3 S 4 nanocomposites via a facile hydrothermal route.…”

External oxidant-free remediation of antibiotics: Activation of oxygen molecules to generate hydroxyl radicals using Co-Fe3S4 nanoflowers

“…Being the naturally abundant ferromagnetic iron-sulfur mineral, greigite (Fe 3 S 4 ) has been widely applied in heterogeneous AOPs. Liu et al [34,35] found an extensive peroxidase-like activity of Fe 3 S 4 , and applied Fe 3 S 4 to remove arsenic. Moreover, Shi et al [36] reported Fe 3 S 4 /H 2 O 2 system to degrade atrazine using •O 2 produced from O 2 under light irritation, demonstrating Fe 3 S 4 ′ s potential to activate O 2 for degrading organic pollutants.…”

“…Moreover, Shi et al [36] reported Fe 3 S 4 /H 2 O 2 system to degrade atrazine using •O 2 produced from O 2 under light irritation, demonstrating Fe 3 S 4 ′ s potential to activate O 2 for degrading organic pollutants. On the other hand, the poor adsorption of dissolved O 2 onto the surface of the catalysts remains a major challenge for using O 2 to degrade contaminants [35,37]. Montemore et al [38] proposed a periodic trend in the of metal surfaces to O 2 activation that metals with a mostly empty d shell, such as Co, Fe, and Rh, presented extremely low adsorption and dissociation barriers.…”