Selective Adsorption Mechanism of Ferric Ions on the …
When copper ores containing pyrite are crushed and ground, many unavoidable Fe3+ ions will be produced and enter the flotation process. At present, the adsorption mechanism of Fe3+ on chalcopyrite and pyrite surfaces is not clear. Here, the adsorption behaviors of Fe3+ on the surfaces of chalcopyrite and pyrite were …
Reduction mechanisms of pyrite cinder-carbon composite pellets …
The non-isothermal reduction mechanisms of pyrite cinder-carbon composite pellets were studied at laboratory scale under argon (Ar) atmosphere. The composite pellets as well as the specimens of separate layers containing pyrite cinder and coal were tested. The degree of reduction was measured by mass loss. The …
Microbial chemolithotrophic oxidation of pyrite in a …
Oxidative weathering of pyrite plays an important role in the biogeochemical cycling of Fe and S in terrestrial environments. While the mechanism and occurrence of biologically accelerated pyrite oxidation under acidic conditions are well established, much less is known about microbially mediated pyrite oxidation at circumneutral pH.
Photocatalytic degradation of malachite green by pyrite …
Diao et al. employed pyrite as a photocatalyst for the degradation of malachite green (MG) and Cr(VI) reduction [264]. Pyrite photocatalysts showed removal efficiency of MG and Cr(VI) reached 96.2 ...
Process Optimization and Reaction Mechanism of …
The aim is to remove copper from a pyrite cinder by optimzing the chlorination roasting process using response surface methodology (RSM) and the reaction mechanism of chlorination roasting based on thermodynamic calculation was discussed. A quadratic model was suggested by RSM to correlate the key parameters, namely, …
Kinetics and Mechanism of Pyrite Formation at …
At pH ∼7 and 80 °C, magnetite was transformed to pyrite within only 19 days, with faster rates in the presence of polysulfides, which formed from the sulfide-mediated reduction of Fe(III) and ...
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Mechanisms of hydroxyl radical production from abiotic oxidation …
The mechanisms that have been proposed in literature are summarized in Fig. 1. (1) From O 2 reduction. The interaction of O 2 with the iron atoms exposed on a pyrite surface forms a surface complex and then O 2 is reduced to adsorbed H 2 O 2 (H 2 O 2(ad)) (Schoonen et al., 2010).The H 2 O 2(ad) is either reduced by pyrite to adsorbed …
Frontiers | Mechanisms of Pyrite Formation Promoted by Sulfate-Reducing
Pyrite, or iron disulfide, is the most common sulfide mineral on the Earth's surface and is widespread through the geological record. Because sulfides are mainly produced by sulfate-reducing bacteria (SRB) in modern sedimentary environments, microorganisms are assumed to drive the formation of iron sulfides, in particular, pyrite. However, the exact …
Reduction mechanisms of pyrite cinder-carbon composite …
The carbon reduction process of pyrite cinder was studied. The thermodynamic results show that the gasification of carbon occurs quickly above 850°C. The volume fraction of CO is close to ...
Inhibition of U(VI) Reduction by Synthetic and Natural Pyrite
Reductive precipitation is an effective method of attenuating the mobility of uranium (U) in subsurface environments. The reduction of U(VI) by synthetic and naturally occurring pyrite was investigated at pH 3.0–9.5. In contrast to thermodynamic calculations that were used to predict UO2(s) precipitation, a mixed U(IV) and U(VI) product (e.g., …
Reductive biomining of pyrite by methanogens
Methanogens can reductively dissolve pyrite (FeS 2) and mobilize iron (Fe) and sulfur (S) under anaerobic conditions.. Biological reduction of FeS 2 takes place via direct extracellular electron transfer (EET) that likely involves electrically conductive components of the S-layer or extracellular polymeric matrix.. Fe(II) solubilized from Fe 1 …
Reductive biomining of pyrite by methanogens
Pyrite (FeS2) is the most abundant iron sulfide mineral in Earth's crust. Until recently, FeS2 has been considered a sink for iron (Fe) and sulfur (S) at low temperature in the absence of oxygen or oxidative weathering, making these elements unavailable to biology. However, anaerobic methanogens can transfer electrons extracellularly to reduce FeS2 via direct …
Pyrite oxidation: a state-of-the-art assessment of the …
Pyrite oxidation is an electrochemical process that consists of three distinct steps, as illustrated in Figure 1. These three steps are the (1) cathodic reaction, (2) electron transport, and (3) anodic reaction. Each step will be discussed separately to simplify this presentation, but the steps must occur more or less simultaneously in the ...
Reductive biomining of pyrite by methanogens
Methanogens can reductively dissolve pyrite (FeS 2) and mobilize iron (Fe) and sulfur (S) under anaerobic conditions. Biological reduction of FeS 2 takes place via direct …
Investigating Abiotic and Biotic Mechanisms of Pyrite Reduction
Abstract. Pyrite (FeS 2) has a very low solubility and therefore has historically been considered a sink for iron (Fe) and sulfur (S) and unavailable to biology in the absence of oxygen and oxidative weathering.Anaerobic methanogens were recently shown to reduce FeS 2 and assimilate Fe and S reduction products to meet nutrient …
Redox performance of pyrite cinder in methane chemical …
Pyrite cinder is a solid by-product in the sulfuric acid production (Fig. 1), which contains Al 2 O 3, SiO 2, CaSO 4 and Fe 2 O 3 [27], [28].The Fe 2 O 3 and CaSO 4 in pyrite cinder can be used as active metal oxides to provide lattice oxygen. The source of pyrite cinder is sufficient, and the annual yield of pyrite cinder is about 10 million tons in …
Mechanistic and kinetic study of pyrite (FeS2)-hydrogen …
determine the kinetics of FeS 2 reduction by H project). - Mechanistic study of pyrite reduction by (Germany), 23rd – 26th January 2012. - Mechanistic and kinetic study of pyrite reduction - tween 90 and 180°C: implication for -2914. with P(H 2)=1bar. ; corresponding to the -750mV/SCE, in the S2O4 2-/S2 redox -)= 0.007-0.0443 ×pH-2 and …
Performance and reaction mechanism of pyrite(FeS2)-based …
PAC was prepared using the mechanical mixing method. First, FeS 2 was crushed and screened into 40–80 mesh powder, before placing the sifted FeS 2 and Al 2 O 3 in an oven and dried at 105 °C for 6–12 h. Then, the appropriate amount of dried FeS 2 powder and Al 2 O 3 was placed in a mixer for 20 min to ensure the two powders were …
IRB800 | Iron Pyrite Removal Bacteria — Great Lakes Bio …
IRB800 is a laboratory-fermented Bacillus spp in a richly fortified mineral carrier intended for remediation to remove excess pyrites in pond water and adjacent pond soils. See our …
Synergism of nitrogen removal and greenhouse gases emission reduction
The efficient removal of nitrate nitrogen (NO 3 −-N) and reduction of greenhouse gas (GHG) emissions in bioretention system (BRS) poses challenges.This study aimed to investigate the performance of a pyrite/biochar-based BRS coupled with microbial fuel cell (MFC) (PBM-BRS) in terms of pollution removal, bioelectricity …
Reductive dissolution of pyrite by methanogenic archaea
Here, we show that methanogens can catalyze the reductive dissolution of FeS2 at low temperature (≤38 °C) and utilize dissolution products to meet cellular iron and sulfur demands associated ...
Investigating Abiotic and Biotic Mechanisms of Pyrite …
Gibb's free energy calculated for abiotic pyrite (FeS 2) reduction to pyrrhotite (Fe 1– x S) and HS – by H 2 at 38°C, an ionic strength of 0.05 M, and at a pH …
[PDF] Microbial acceleration of aerobic pyrite oxidation at
The ability of aerobic microbial activity to accelerate pyrite oxidation and expand the potential contribution of micro‐organisms to continental sulfide mineral weathering around the time of the Great Oxidation Event to include neutral‐pH environments are demonstrated. Pyrite (FeS2) is the most abundant sulfide mineral on …
The roles of pyrite for enhancing reductive removal of …
The kinetics of nitrobenzene removal by ZVI, pyrite, and the mixture of ZVI and pyrite at pH 0 6.0 are demonstrated in Fig. 1.ZVI (0.5 g/L) or pyrite (2.0 g/L) alone is not effective for nitrobenzene removal, as shown in Fig. 1 (a) and (b), and only ∼0.03 mM nitrobenzene is removed by either ZVI or pyrite in 300 min. There were negligible …
Investigating Abiotic and Biotic Mechanisms of Pyrite …
Pyrite (FeS 2) has a very low solubility and therefore has historically been considered a sink for iron (Fe) and sulfur (S) and unavailable to biology in the absence …
IRB800 | Iron Pyrite Removal Bacteria — Great Lakes Bio …
IRB800 is a concentrated product with a unique species of bacteria that is proven to remove excess iron pyrite contamination in aquaculture ponds. Excessive levels of pyrite have long been associated with low productivity and crop failure in fish and shrimp culture. In aquaculture, the excessive levels of pyrite negati
Effect of pH on aqueous Se(IV) reduction by pyrite.
The positive correlation between reaction rate and pH disagrees with the theories that protons are consumed when HSeO3− is reduced to Se0, and negative charge density on pyrite surface increases as pH increases, and a ferrous iron mediated electron transfer mechanism is proposed to operate during the reduction of aqueous Se(IV) by …
Investigating Abiotic and Biotic Mechanisms of Pyrite Reduction
Pyrite (FeS2) has a very low solubility and therefore has historically been considered a sink for iron (Fe) and sulfur (S) and unavailable to biology in the absence of oxygen and oxidative weathering. Anaerobic methanogens were recently shown to reduce FeS2 and assimilate Fe and S reduction products to meet nutrient demands. However, the …
Mechanisms and rates of pyrite formation from
Hydrothermal experiments of in-situ pyrite precipitation were conducted at 400 and 450 °C and between ∼400 and ∼800 bar in aqueous solutions NaCl-KCl-S-FeSO 4 /FeCl 2 (±silicate minerals) of previously determined Fe isotope composition. The chemical composition of the experimental systems and the major fluid parameters at each …