Electrochemical Characterisation of the Ce(IV) Limiting Carbonate Complex

Riglet-Martial, Chantal; Vitorge, Pierre; Calmon, Véronique

doi:10.1524/ract.1998.82.special-issue.69

Cited by 7 publications

(8 citation statements)

References 8 publications

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“…2, varying the Ce (III) concentration does not change the E 1/2 , which has been reported by other studies at a lower CO 3 2− concentration of 1 M. 24,43 This result also indicates Ce(III) in carbonate media is a mononuclear complex as the E 1/2 is independent from the concentration of Ce(III). 24 If the Ce carbonate complex is a polynuclear complex, the E 1/2 would be expected to change with the Ce concentration. 24,43 OH − concentration.-The study by Hobart et al 18 suggested the stability of Tb(IV) and Pr(IV) complexes in CO 3 2− media can be increased by adjusting the concentration of OH − to approximately 1 M. To study this more, the effects of the concentration of KOH on the E 1/2 of Ce was examined.…”

Section: Resultssupporting

confidence: 82%

“…As seen in Fig. 2, varying the Ce (III) concentration does not change the E 1/2 , which has been reported by other studies at a lower CO 3 2− concentration of 1 M. 24,43 This result also indicates Ce(III) in carbonate media is a mononuclear complex as the E 1/2 is independent from the concentration of Ce(III). 24 If the Ce carbonate complex is a polynuclear complex, the E 1/2 would be expected to change with the Ce concentration.…”

Section: Resultssupporting

confidence: 81%

“…Studies of Ce(IV) in lower CO 3 2− concentration media (around 1 M) suggest the stoichiometry for the Ce(IV) limiting complex is Ce(CO 3 ) 6 8− . 23,24 To date, there is no complete study on the effect of solution conditions on the half-wave potential (E 1/2 ) of Ce(IV), Pr(IV) and Tb(IV) complexes and no suggested coordination environment of the Ce(IV) complex in concentrated carbonate media (i.e. ⩾5.5 M).…”

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confidence: 99%

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Electrochemical Oxidation and Speciation of Lanthanides in Potassium Carbonate Solution

Tse

Bessen

Galley

et al. 2022

J. Electrochem. Soc.

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Increasing lanthanide demand to support energy goals drives the need to develop more efficient approaches to separate lanthanide metals. Most current approaches for intra-lanthanide separations are not very selective and are based on small differences in ionic radii. Concentrated potassium carbonate media has shown some potential to enable oxidation of Pr and Tb to their tetravalent states, which could enable a separation based on differences in oxidation states, but little is known regarding the general system chemistry. This work completes a detailed examination of cerium (Ce) redox chemistry in concentrated carbonate media to support the development of Pr and Tb oxidation studies. The half-wave potential (E1/2) of the Ce(III)/(IV) redox couple is evaluated under various solution conditions and computational modeling of carbonate coordination environments is discussed. Cyclic voltammetry shows higher carbonate concentrations and temperatures can lower the potential required to oxidize Ce(III). Chronoabsorptometry shows Ce(III) and Ce(IV) carbonate complexes are chemically stable and reversible. Computational modeling suggests the most likely coordination environment for the Ce(IV) complex is Ce(CO3)4(OH)5- which is a less entropically favored complex than the lowest energy Ce(III) complex, Ce(CO3)4 5-.

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Section: Resultssupporting

confidence: 82%

Section: Resultssupporting

confidence: 81%

mentioning

confidence: 99%

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Electrochemical Oxidation and Speciation of Lanthanides in Potassium Carbonate Solution

Tse

Bessen

Galley

et al. 2022

J. Electrochem. Soc.

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“…Complexation by carbonate could thus induce the oxidation of trivalent Ce to tetravalent form as previously stated by Stumm and Morgan (1996) for Fe(III)/Fe(II) redox couple. Moreover, Doležal and Novák (1959), Möller and Bau (1993) and Riglet-Martial et al (1998) have shown that strong carbonato-Ce-complexes may form following the half oxidation reaction:…”

Section: Mechanism Of Cerium Anomaly Developmentmentioning

confidence: 99%

New insights into cerium anomalies in organic-rich alkaline waters

et al. 2008

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International audienceCerium anomaly development in natural waters is commonly related to the mechanism of oxidative scavenging of tetravalent cerium by iron and/or manganese oxides. In this study, a new mechanism for the development of Ce anomalies is described, which combines the oxidation of Ce at high pH by carbonate and the preferential adsorption of Ce(IV) to humic acids. This new mechanism was experimentally elucidated by studying the competition between carbonate and humic acids for complexing rare earth elements (REE). These experiments showed that above pH 8.2,8.6 or 8.7 (with decreasing alkalinity from 10(-2) to 10(-3) mol L-1), Ce(III) is readily oxidized into Ce(W), which is then preferentially adsorbed onto hurnic acids. This preferential uptake of Ce results in the development of a negative Ce anomaly (as low as 0.05) in the "truly" dissolved part of the solution (i.e., <5 kDa), and a complementary positive anomaly (up to 1.22) occurs in the organic colloidal fraction. The positive and negative Ce anomalies remained hidden until the organic and inorganic fractions of the solution were separated. Therefore, Ce anomalies became apparent only after ultrafiltration of the waters and the subsequent isolation of the two fractions. The Ce anomaly is thus more likely to be a proxy of redox conditions in ultrafiltered waters than in unfiltered waters or in waters filtered to < 0.2 mu m. The removal (e.g., by coagulation and/or flocculation) of organic molecules in organic-rich alkaline waters might lead to the development of a negative Ce anomaly in the resulting organic-poor waters. In contrast, some organic-poor alkaline waters may develop positive Ce anomalies due to preferential complexation of Ce(IV) by dissolved carbonate

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“…Several studies have shown that carbonate ions can form complexes with ceria particles that are stable over a wide pH range. 31,32 Ammonium carbonate is also commonly used in cleaning glass surfaces (similar to silicon dioxide surfaces). 33,34 We will discuss the role of ascorbic acid later in this section.…”

Section: Resultsmentioning

confidence: 99%

Cleaning Solutions for Removal of ∼30 nm Ceria Particles from Proline and Citric Acid Containing Slurries Deposited on Silicon Dioxide and Silicon Nitride Surfaces

Gowda

Seo

Ranaweera

et al. 2020

ECS J. Solid State Sci. Technol.

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A previously developed aqueous cleaning solution (4.2 mol l−1 each of H2O2 and NH4OH) was found to be ineffective in cleaning oxide/nitride surfaces after contamination with ceria particles from slurries containing proline or citric acid. However, a cleaning solution consisting of 1 wt% ascorbic acid, 1 wt% ammonium carbonate and 50 ppm triton X-100 at pH 12, aided by ultrasonic cleaning, removed these ceria particles, even those as small as ∼30 nm, from both oxide and nitride surfaces with efficiencies >99% as determined by AFM imaging. Fourier transform infrared (FTIR) spectroscopy results indicated that ceria particles treated with these additives can also bind with oxide/nitride surfaces through Si–O–C and Si–O–H bonds, in addition to any Ce–O–Si, where the C and H atoms are from the additives adsorbed on the ceria particles. All these bonds are broken effectively by the nucleophilic attack of hydroxyl anions in the cleaning solution while triton X-100 in the cleaning solution reduces adhesion between the particles and the film surface and facilitates cleaning via a wetting mechanism. More importantly, ascorbic acid and ammonium carbonate prevent particle redeposition by complexing with the removed particles and blocking the active Ce3+ species on their surface.

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Electrochemical Characterisation of the Ce(IV) Limiting Carbonate Complex

Cited by 7 publications

References 8 publications

Electrochemical Oxidation and Speciation of Lanthanides in Potassium Carbonate Solution

Electrochemical Oxidation and Speciation of Lanthanides in Potassium Carbonate Solution

New insights into cerium anomalies in organic-rich alkaline waters

Cleaning Solutions for Removal of ∼30 nm Ceria Particles from Proline and Citric Acid Containing Slurries Deposited on Silicon Dioxide and Silicon Nitride Surfaces

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