Speciation of the H2SO4–Fe2(SO4)3–FeSO4–H2O system and development of an expression to predict the redox potential of the Fe3+/Fe2+ couple up to 150°C

Yue, Guikuan; Zhao, Liming; Olvera, Oscar G.; Asselin, Edouard

doi:10.1016/j.hydromet.2014.05.008

Cited by 63 publications

(74 citation statements)

References 67 publications

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“…Both E 0 and E 0 1 vary as a function of temperature. Using Equation (1) and the E 01 value of 0.67 [12] the total Fe 3+ /Fe 2+ concentration ratio at 25˝C and 750 mV is found to be approximately 22, in good agreement with the ratio suggested from experimental data ( Figure 7 from [52]). It should be noted that E 01 values at temperatures other than 25˝C are not available so that the ratio of concentrations of Fe 3+ /Fe 2+ as per Equation (1) cannot be calculated for other temperatures.…”

Section: Effect Of 4 Mmol Iron Additionsupporting

confidence: 83%

“…The value of E at each temperature may be calculated using Equation (13) from [51], which requires input of only the "nominal" Fe 3+ /Fe 2+ concentration ratio at 25˝C for which we used the value of 22. Via regression analysis an expression ( [52], Equation (11)) enabling the calculation of E 0 (Equation (2)) in acid iron sulfate systems as a function of temperature has been derived. By applying this expression, E 0 values of 770, 793, 806, 817, 841, 849 and 857 mV are calculated for 25, 35, 43, 50, 65, 70 and 75˝C, respectively.…”

Section: Effect Of 4 Mmol Iron Additionmentioning

confidence: 99%

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Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Wei

Qian

et al. 2016

Minerals

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Abstract:To better understand chalcopyrite leach mechanisms and kinetics, for improved Cu extraction during hydrometallurgical processing, chalcopyrite leaching has been conducted at solution redox potential 750 mV, 35-75˝C, and pH 1.0 with and without aqueous iron addition, and pH 1.5 and 2.0 without aqueous iron addition. The activation energy (E a ) values derived indicate chalcopyrite dissolution is initially surface chemical reaction controlled, which is associated with the activities of Fe 3+ and H + with reaction orders of 0.12 and´0.28, respectively. A surface diffusion controlled mechanism is proposed for the later leaching stage with correspondingly low E a values. Surface analyses indicate surface products (predominantly S n 2´a nd S 0 ) did not inhibit chalcopyrite dissolution, consistent with the increased surface area normalised leach rate during the later stage. The addition of aqueous iron plays an important role in accelerating Cu leaching rates, especially at lower temperature, primarily by reducing the length of time of the initial surface chemical reaction controlled stage.

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Section: Effect Of 4 Mmol Iron Additionsupporting

confidence: 83%

Section: Effect Of 4 Mmol Iron Additionmentioning

confidence: 99%

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Wei

Qian

et al. 2016

Minerals

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“…The proposed model was validated by our own experimental data and results published by others. Detailed information on the speciation model can be found elsewhere [45]. Table 2 presents the obtained concentrations of free Fe 3+ and Fe 2+ ions in the aqueous Fe(II)-Fe(III)-H 2 SO 4 solutions in the range of 25-150 • C according to the developed speciation model.…”

Section: Resultsmentioning

confidence: 99%

“…This assumption is approximately correct, because our experimental results of measured reversible potentials of the Fe 3+ /Fe 2+ couple were in good agreement with those calculated by our previous speciation model. Detailed information on the potential correction can be found elsewhere [45].…”

Section: Correction Of the Measured Potentials To She At 25 • Cmentioning

confidence: 99%

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Kinetics of Ferric Ion Reduction on Chalcopyrite and its Influence on Leaching up to 150 °C

Yue¹,

Asselin²

2014

Electrochimica Acta

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Pt^II‐Catalyzed Hydroxylation of Terminal Aliphatic C(sp³)−H Bonds with Molecular Oxygen

Janssen

Vos

2019

Chemistry A European J

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The practical application of Shilov‐type Pt catalysis to the selective hydroxylation of terminal aliphatic C−H bonds remains a formidable challenge, due to difficulties in replacing PtIV with a more economically viable oxidant, particularly O2. We report the potential of employing FeCl2 as a suitable redox mediator to overcome the kinetic hurdles related to the direct use of O2 in the Pt reoxidation. For the selective conversion of butyric acid to γ‐hydroxybutyric acid (GHB), a significantly enhanced catalyst activity and stability (turnover numbers (TON)>30) were achieved under 20 bar O2 in comparison to current state‐of‐the‐art systems (TON<10). In this regard, essential reaction parameters affecting the overall activity were identified, along with specific additives to attain catalyst stability at longer reaction times. Notably, deactivation by reduction to Pt0 was prevented by the addition of monodentate pyridine derivatives, such as 2‐fluoropyridine, but also by introducing varying partial pressures of N2 in the gaseous atmosphere. Finally, stability tests revealed the involvement of PtII and FeCl2 in catalyzing the non‐selective overoxidation of GHB. Accordingly, in situ esterification with boric acid proved to be a suitable strategy to maintain enhanced selectivities at much higher conversions (TON>60). Altogether, a useful catalytic system for the selective hydroxylation of primary aliphatic C−H bonds with O2 is presented.

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Speciation of the H2SO4–Fe2(SO4)3–FeSO4–H2O system and development of an expression to predict the redox potential of the Fe3+/Fe2+ couple up to 150°C

Cited by 63 publications

References 67 publications

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Kinetics of Ferric Ion Reduction on Chalcopyrite and its Influence on Leaching up to 150 °C

Pt^II‐Catalyzed Hydroxylation of Terminal Aliphatic C(sp³)−H Bonds with Molecular Oxygen

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Speciation of the H2SO4–Fe2(SO4)3–FeSO4–H2O system and development of an expression to predict the redox potential of the Fe3+/Fe2+ couple up to 150°C

Cited by 63 publications

References 67 publications

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Kinetics of Ferric Ion Reduction on Chalcopyrite and its Influence on Leaching up to 150 °C

PtII‐Catalyzed Hydroxylation of Terminal Aliphatic C(sp3)−H Bonds with Molecular Oxygen

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Product

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Pt^II‐Catalyzed Hydroxylation of Terminal Aliphatic C(sp³)−H Bonds with Molecular Oxygen