Precipitation of Cerium Sulfate Converted from Cerium Oxide in Sulfuric Acid Solutions and the Conversion Kinetics

Um, Namil; Hirato, Tetsuji

doi:10.2320/matertrans.m-m2012826

Cited by 34 publications

(21 citation statements)

References 17 publications

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“…Ce(IV) after 48 h at 125 °C [191]. On the other hand, the recovery of cerium from fluorescent lamps is subordinate to the recovery of yttrium and europium phosphors, which are more valuable [192].…”

Section: Environmental Treatment and Recyclingmentioning

confidence: 99%

Electrochemical redox processes involving soluble cerium species

Arenas

León

Walsh

2016

Electrochimica Acta

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Anodic oxidation of cerous ions and cathodic reduction of ceric ions, in aqueous acidic solutions, play an important role in electrochemical processes at laboratory and industrial scale. Ceric ions, which have been used for oxidation of organic wastes and off-gases in environmental treatment, are a wellestablished oxidant for indirect organic synthesis and specialised cleaning processes, including oxide film removal from tanks and process pipework in nuclear decontamination. They also provide a classical reagent for chemical analysis in the laboratory. The reversible oxidation of cerous ions is an important reaction in the positive compartment of various redox flow batteries during charge and discharge cycling. A knowledge of the thermodynamics and kinetics of the redox reaction is critical to an understanding of the role of cerium redox species in these applications. Suitable choices of electrode material (metal or ceramic; coated or uncoated), geometry/structure (2-or 3-dimensional) and electrolyte flow conditions (hence an acceptable mass transport rate) are critical to achieving effective electrocatalysis, a high performance and a long lifetime. This review considers the electrochemistry of soluble cerium species and their diverse uses in electrochemical technology, especially for redox flow batteries and mediated electrochemical oxidation.

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Section: Environmental Treatment and Recyclingmentioning

confidence: 99%

Electrochemical redox processes involving soluble cerium species

Arenas

León

Walsh

2016

Electrochimica Acta

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“…According to Um et al, 13) CeO 2 was very slowly dissolved in acid solutions; it took more than 48 h to dissolve 0.02 mol CeO 2 powder with 2.5 µm average particle size completely in 0.1 dm 3 sulfuric acid solutions (8 mol/dm 3 ) at 125°C. The dissolution rate of CeO 2 increased with increasing reaction temperature in the range from 105 to 135°C and increasing sulfuric acid concentration in the range from 8 to 12 mol/dm 3 .…”

Section: ¹1mentioning

confidence: 99%

“…13) It was found that the reaction rate for the dissolution of CeO 2 can be expressed by a shrinking core model that describes the fluid-solid reaction kinetics of dense (nonporous) particles. 1417) Therefore, the experimental data of Al 2 O 3 dissolution, which was performed under various sulfuric acid concentrations and reaction temperatures, were made to fit a shrinking core model to Al-dissolution vs. time curves.…”

Section: Kinetics Analysismentioning

confidence: 99%

“…Following kinetics data of CeO 2 and Al 2 O 3 dissolution, cerium and aluminum could be separated by leaching (case 2). In the case of CeO 2 , the kinetics data calculated by Um et al 13) was used in this study. The kinetics data of Al 2 O 3 dissolution performed under various conditions of sulfuric acid concentration and reaction temperature, as shown in Figs.…”

Section: Leaching (Case 2)mentioning

confidence: 99%

“…As for the dissolution of CeO 2 , the following equation was obtained: 13) k ¼ 1:4268 Â 10 8 e À14831=T C 6:54 : ð14Þ…”

Section: Leaching (Case 2)mentioning

confidence: 99%

See 2 more Smart Citations

Dissolution Behavior of La2O3, Pr2O3, Nd2O3, CaO and Al2O3 in Sulfuric Acid Solutions and Study of Cerium Recovery from Rare Earth Polishing Powder Waste via Two-Stage Sulfuric Acid Leaching

Hirato

2013

Mater. Trans.

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This study describes a hydrometallurgical process to investigate the cerium recovery from rare earth polishing powder waste (REPPW) containing main elements such as cerium, lanthanum, praseodymium, neodymium, calcium and aluminum. First, dissolution experiments on La 2 O 3 , Pr 2 O 3 , Nd 2 O 3 , CaO and Al 2 O 3 with 5 µm particle size in sulfuric acid solutions were carried out using a batch reactor with various acid concentrations (115 mol/dm 3 ) at different temperatures (30180°C). The effects of these two parameters on the dissolution reaction were studied. The obtained results showed that two sequential leaching steps were needed to separate cerium from the mixture of CeO 2 , La 2 O 3 , Pr 2 O 3 , Nd 2 O 3 , CaO and Al 2 O 3 . The total process for cerium recovery from REPPW via two-stage acid leaching was then developed through the collection of experimental results. Moreover, the dissolution rate of Al 2 O 3 was expressed by a shrinking core kinetics model. The variation of the dissolution rate constant with temperature obeyed the Arrhenius equation with activation energy of 130 kJ·mol ¹1 and reaction rate constant as a function of the acid concentration of C 0.41. On the basis of the above data, a k-T (reaction rate constant-reaction temperature) diagram for a CeO 2 Al 2 O 3 H 2 SO 4 H 2 O system that permits rational extraction of CeO 2 and Al 2 O 3 was devised.

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Thermochemical evaluation of oxygen transport membranes under oxy‐combustion conditions in a pilot‐scale facility

Portillo

Cano

Fernández

et al. 2020

J of Chemical Tech & Biotech

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BACKGROUND Control of greenhouse gas emissions has become one of the most important challenges faced by humanity. Among the various approaches to mitigating CO2 emissions, carbon capture and storage (CCS) is considered one of the most promising clean coal options for the future because it can be implemented in the short and medium terms at the industrial scale. Among CCS techniques, oxy‐combustion offers advantages in using pure oxygen (O2) as a comburent, where in a flue gas composed mainly of CO2 and water vapor is generated. Cryogenic air separation is the only available technology that can provide the required amount of O2, but this process requires large amounts of energy and is costly, which make its large‐scales implementation difficult. RESULTS In this framework, oxygen transport membranes are being researched as an O2 supplier unit because they offer advantages from a techno‐economic view point. In the present work, the thermochemical stabilities of La0.6Sr0.4Co0.2Fe0.8O3 and Cobalt‐doped Ce0.9Gd0.1O were evaluated to obtain information on their behavior in oxy‐combustion atmospheres. Experiments were performed in a circulating fluidized bed boiler of a pilot plant using an experimental sampling train. Samples of the two materials were characterized by X‐ray diffraction, X‐ray fluorescence, infrared spectroscopy, Raman spectroscopy, scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, and Brunauer–Emmett–Teller analysis. CONCLUSIONS The results revealed that both materials were susceptible to the presence of species that originated from flue gas, materials comprising the boiler and ducts, and coal ash, and that the CGO_Co material showed better performance than the other studied material. © 2020 Society of Chemical Industry

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Precipitation of Cerium Sulfate Converted from Cerium Oxide in Sulfuric Acid Solutions and the Conversion Kinetics

Cited by 34 publications

References 17 publications

Electrochemical redox processes involving soluble cerium species

Electrochemical redox processes involving soluble cerium species

Dissolution Behavior of La<sub>2</sub>O<sub>3</sub>, Pr<sub>2</sub>O<sub>3</sub>, Nd<sub>2</sub>O<sub>3</sub>, CaO and Al<sub>2</sub>O<sub>3</sub> in Sulfuric Acid Solutions and Study of Cerium Recovery from Rare Earth Polishing Powder Waste via Two-Stage Sulfuric Acid Leaching

Thermochemical evaluation of oxygen transport membranes under oxy‐combustion conditions in a pilot‐scale facility

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