Electrochemical study of binary and ternary copper complexes in ammonia-chloride medium

Vazquez‐Arenas, Jorge; Lázaro, Isabel; Cruz, Roel

doi:10.1016/j.electacta.2007.03.062

Cited by 41 publications

(27 citation statements)

References 17 publications

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“…After the formation of tetraammine complex at NH 4 + /Cu 2+ near 6-15 the concentration of Cu 2+ ions is quite low and insufficient for attaining the product of copper(II) hydroxide solubility equal to 5.6 × 10 −20 . On the other hand, in a strongly alkaline medium (NH 4 + /Cu 2+ > 20, pH > 12.5) the formation of CuO is possible due to a decreased stability of soluble ammonia copper complexes [25]. In addition, the high ammonia concentrations can cause desilication of the zeolite surface, which is desirable to avoid.…”

Section: State Of Copper Ions In Aqueous and Water-ammonia Solutionsmentioning

confidence: 98%

Cu-substituted ZSM-5 catalyst: Controlling of DeNO reactivity via ion-exchange mode with copper–ammonia solution

Yashnik

Ismagilov

2015

Applied Catalysis B: Environmental

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Section: State Of Copper Ions In Aqueous and Water-ammonia Solutionsmentioning

confidence: 98%

Cu-substituted ZSM-5 catalyst: Controlling of DeNO reactivity via ion-exchange mode with copper–ammonia solution

Yashnik

Ismagilov

2015

Applied Catalysis B: Environmental

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“…On the other hand, the electrodeposition of copper from ammoniacal solutions onto substrates other than iron has been studied extensively. Based on thermodynamic and electrochemical studies, numerous authors agree that the electrodeposition of copper from ammoniacal solutions of different compositions occurs via the reduction of cupric tetrammine to cuprous diammine, which is then further reduced to metallic copper (Darchen et al, 1997;Giannopoulou et al, 2009;Graham et al, 2002;Grujicic and Pesic, 2005;Nila and González, 1996a;Nila and González, 1996b;Ramos et al, 2001;Vazquez-Arenas et al, 2007a;Vazquez-Arenas et al, 2007b). The direct reduction of cupric tetrammine to metallic copper is also thought to take place at more negative applied potentials (Grujicic and Pesic, 2005).…”

Section: Introductionmentioning

confidence: 99%

The passivation of iron in ammoniacal solutions containing copper (II) ions

D'Aloya

Nikoloski

2012

Hydrometallurgy

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In the present study it was found that the presence of millimolar amounts of copper (II) ions in ammoniacal solutions leads to the spontaneous formation of a stable passive layer on metallic iron and iron alloys with nickel and cobalt, under conditions in which they would otherwise remain in active dissolution. This finding may be of significance to industrial processes which employ ammoniacal solutions to leach metal values from materials rich in metallic iron, such as, for example, laterite ores which have undergone a reductive pre-treatment.The spontaneous passivation is found to take place regardless of the presence or practical absence of dissolved oxygen, and occurs more readily the higher the copper concentration and the lower the ammonia-ammonium bicarbonate concentration, though it does not take place in ammonia-free aqueous solutions of similar copper (II) ion concentrations.Electrochemical and scanning electron microscopy / energy dispersive X-ray spectroscopy (SEM/EDX) investigations conducted as part of this study showed that the observed passivation is promoted by the cementation of copper onto the actively dissolving iron surface, and subsequently by its re-dissolution. Such process is thought to create favourable conditions which promote the formation of a stable passive layer on the iron surface.

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“…Cu(NH 3 ) 2 Cl 2 exhibits a wide predominance in neutral-alkaline zone at the chloride concentration lower than 0.29 mol/kg (−lg m[Cl − ]<0.537 6), while those species have been mentioned in Refs. [12,24]. In these diagrams, the appearance of CuCl precipitates is observed in the acidic zone and Cu 2 O in the acidic and alkaline zone, whose pH value depends on −lg m[Cl − ], while the two solids have been mentioned in Refs.…”

Section: Predominance Existence Diagrams Of System Cu(i)-nh 3 -Cl − -mentioning

confidence: 96%

“…However, the non-ideality of the solution was not considered for these algorithms so that some errors may be produced inevitably for concentrated solution. A recent study on the speciation of copper in ammonia-chloride solutions was conducted using chemical equilibrium software MEDUSA [12]. Debye-Hückel equation was used to calculate the activity coefficient for all aqueous species, but the activity coefficient model used is inadequate for computation concentrated solution system because it works just well at relatively low ionic strength (0.001 mol/kg≤ I ≤0.1 mol/kg).…”

Section: Introductionmentioning

confidence: 99%

Real-solution stability diagrams for copper-ammonia-chloride-water system

Wang

Chen

Yin

et al. 2011

J. Cent. South Univ. Technol.

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A comprehensive thermodynamic model, which combined the Helgeson−Kirkham−Flowers (HKF) equation of state for standard-state thermodynamic properties of all species with realistic activity coefficient model developed by BROMLEY, was used to calculate the thermodynamic equilibrium, and a graphical method was developed to construct predominance existence diagrams (PED) for copper-ammonia-chloride in the presence of realistically modeled aqueous solutions. The existence of the different predominant chemical species for Cu(II) predicted by the diagrams was corroborated by spectrophotometrical studies and X-ray diffractometry. The simulated and experimental results indicate that the predominance of a given species in solution strongly depends on the pH value in this system. More quantitative information on real copper hydrometallurgy in the presence of ammonia and chloride can be obtained from these diagrams compared with the conventional predominance existence diagrams.

show abstract

Electrochemical study of binary and ternary copper complexes in ammonia-chloride medium

Cited by 41 publications

References 17 publications

Cu-substituted ZSM-5 catalyst: Controlling of DeNO reactivity via ion-exchange mode with copper–ammonia solution

Cu-substituted ZSM-5 catalyst: Controlling of DeNO reactivity via ion-exchange mode with copper–ammonia solution

The passivation of iron in ammoniacal solutions containing copper (II) ions

Real-solution stability diagrams for copper-ammonia-chloride-water system

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