The authors have carried out molecular modeling of clusters of simple structure and ring structure pyrite. It is suggested to analyze bonding of a collecting agent and cluster atoms using the collector capacity forecasting index. It is shown that butyl dixanthate more vigorously connects to cluster atoms than thionocarbamates, e.g., Z …

Refractory sulphidic ore with gold captured in pyrite has motivated researchers to find efficient means to break down pyrite to make gold accessible and, ultimately, improve gold extraction. Thus, the dissolution of pyrite was investigated to understand the mechanism and find the corresponding kinetics in a nitric acid solution. …

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 demands. However, the …

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 …

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 ...

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 …

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 …

The ability of aerobic microbial activity to accelerate pyrite oxidation and expand the potential contribution of micro‐organisms to continental sulfide mineral …

Hexavalent chromium is a known toxic and mobile contaminant in the environment. Reduction of Cr (VI) using Fe (II) compounds is one of the most common practices in dealing with Cr (VI) as a contaminant. Among the various Fe (II) salts suggested for Cr (VI) treatment, pyrite, also a potential waste as well as a natural …

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., …

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 …

Direct access to FeS2 is required to catalyze its reduction and/or to assimilate iron monosulfide that likely forms through coupled reductive dissolution and precipitation, …

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 …

The mechanism of the initial steps of pyrite (100) surface oxidation was investigated in detail by means of density functional theory/plane-wave calculations. Pyrite oxidation is related to many environmental and technological issues, and its mechanism has not been completely understood. A chemical picture of the pyrite oxidation process in the …

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 …

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 …

Capture of Mo by FeS2 is an important sink for marine Mo. X-ray spectroscopy has shown that Mo forms Mo-Fe-S cuboidal clusters on pyrite. Reduction of MoVI must occur to stabilize these structures.

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 …

Under acidic conditions, the surface of pyrite is positively charged due to the dominant soluble species of iron (FeOH 2 +); while under neutral and alkaline conditions, the dominant species in the surface of pyrite is FeO −.However, in the degradation stage, after 120 min of reactions, 37.0% and 48.5% of MG could be degraded at pHs 7.0 and …

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 …

Pyrite is a common and abundant sulfidic mineral subject to oxidation. The weathering characteristics of rock-bearing pyrite sometimes impose serious influences on the surrounding environment as the oxidation of pyrite (FeS2) generates acid drainage that results in the acceleration of rock weathering and the discharge of heavy metals into the …

Pyrite concentrate is a common by-product obtained after Pb and Zn sulfide minerals flotation. Pyrolysis at 600 ∼ 700 °C in an inert atmosphere is an effective way to comprehensively utilize pyrite concentrate. ... the recovery and separation of iron and chromium from NAPL residue by metallization reduction roasting−magnetic separation ...

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 ...

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 ...

Our results suggest that rates of pyritization vs. vivianite formation are regulated by SRB activity at the cellular scale, which enhances phosphate release into …

The rates of pyrite oxidation by Cr (VI) from pH 2.0 to 11.0 were found to be zero-order with respect to the concentration of initial Cr (VI) and second order with respect to the ratio of pyrite surface area to solution volume. The activation energy of the Cr (VI) reduction in the temperature range of 10–50 °C was 73 kJ/mol.

Liên hệ đặt hàng. - IRB800 giúp chuyển hóa phèn từ dạng có hại thành có lợi, dễ gây tảo, tăng lượng oxy hòa tan. - IRB800 giúp xử lý trường hợp bị nhớt đáy ao nuôi bị nhiễm phèn. - IRB800 sử dụng tốt cho ao nuôi cả nước mặn và nước ngọt. - Giai đoạn chuẩn bị ao ...

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 …

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 …

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 …