Solvent Extraction Of Cerium Research Articles

Optimization of cerium extraction from aqueous solutions by response surface methodology employing 4‐factor Box‐Behnken design

AbstractIn this research, the solvent extraction of Cerium (III) using Cyanex 572 has been investigated under variations of the pH, extractant concentration, nitrate ion concentration, and contact time. Box‐Behnken design and analysis of variance were applied to determine the main effects and their interactions. The high R2 value obtained from the developed model indicated a good correlation between the predicted and measured data. Contact time had no significant effect on the extraction of cerium. pH and extractant concentration were the most significant parameters affecting the cerium extraction under the examined conditions. The developed model was applied to find out the optimum values of the selected variables for the maximum extraction of cerium. The nature of diluent influences the extraction efficiency of Cerium (III). Kerosene was found to be efficient diluent for the extraction of cerium in terms of better extraction capability as investigated.

Solvent extraction of cerium from various solutions by organophosphorus- based extractants: a review

Solvent extraction of cerium from various solutions by organophosphorus- based extractants: a review

Extraction equilibria of cerium(IV) with Cyanex 923 followed by precipitation kinetics of cerium(III) oxalate from sulfate solution

The phenomenon studies on solvent extraction of cerium(IV) using Cyanex 923 followed by the precipitation kinetics and recovery of cerium(III) oxalate has been investigated from the sulfate media. The extraction equilibria investigated with varying concentrations of extractant into the organic phase and acid into the aqueous phase could reveal the solvation of [Ce(SO4)2·2L·HSO4-]org species. The thermodynamic properties determined at different temperatures exhibited the exothermic nature of extraction (ΔH°, −12.2 kJ·mol−1). The quantitative extraction and back-extraction of cerium(IV) in sulfate media could be achieved in three stages of counter-current contact at an organic-to-aqueous ratio of 2/3 and 3/2, respectively. Ce-enrich stripped solution was subsequently recovered as cerium(III) precipitates by treating with oxalic acid. Precipitation with the optimized dosage of Ce:H2C2O4 as 1:≥10 yielded the oxalate products of unlike physico-chemical characteristics, while precipitating at different temperatures. The precipitation kinetics was found to have good fits to the Avrami equation; where, n values < 1 indicated for instantaneous nucleation that leads to flakes-shape growth of precipitates and supported by the surface morphological study. Evaluation of the apparent activation energy (Ea, 8.6 kJ·mol−1) indicated that the precipitation reaction follows a diffusion-controlled mechanism as supported by the surface site saturation of cerium(III) oxalate through the constants of Avrami equation. The findings of the present study may supply a potential way of extracting cerium(IV) from sulfate leach liquor of rare earths ores and the precipitation recovery of cerium(III) oxalate as the suitable precursor of (nano)crystalline ceria.

The investigation of stoichiometry and kinetics of cerium (IV) solvent extraction from sulfate medium by Cyanex 272 and 301 using single drop column

In the present study, the solvent extraction of cerium (IV) from sulfate medium was investigated by Cyanex 272 and 301. The main objective was to increase our understanding of the behavior of analogous extractants, but different in donor atom, which were achieved by batch and kinetics investigations. This allows better selection of extractants for similar approaches in future works. The investigation of extraction kinetics using single drop columns provides this work with a simpler approach in term of overall procedure for the separation of cerium ions from aqueous solutions, which allows finding how experimental conditions control the rate of reaction. The effects of parameters such as pH, extractant concentration, organic to aqueous volume, and temperature were studied under batch conditions. The complete extraction of 200mgL−1 Ce (IV) at pH of 4 was obtained either by Cyanex 272 or 301 diluted in kerosene. Results shows that regarding the structural substitution of oxygen with sulfur, Cyanex 272 has a better performance in a lower concentration, while Cyanex 301 shows higher extraction percentage at lower pH. The extraction by Cyanex 272 and 301 was exothermic and endothermic, respectively. Results of reaction kinetics revealed that by considering the correction of droplets residence time, the rate of extraction either by Cyanex 272 or 301 is independent of the height of the column. Thus, the effects of extractants and cerium concentrations along with the pH of aqueous solution allowed finding the rate of extraction. The cerium mass flux increased by droplet diameter, indicating the contribution of mass diffusion in the extraction.

Comparative study on Ce (III) and La (III) solvent extraction and separation from a nitric acid medium by D2EHPA and Cyanex272

The solvent extraction of Cerium(III) and Lanthanum(III) from nitric acid solution using the organophosphorous extractants Di-(2-ethyl hexyl) phosphate (D2EHPA) and di-2,4,4- trimethylpentyl phosphoric acid (Cyanex272) in kerosene was investigated. In this study, the magnitude of the extraction of Ce(III) was found to be more significant with Cyanex272 than D2EHPA. D2EHPA was found to be a better extractant for La(III). Among the two extractants, Cyanex272 was used for the separation of Ce from La in three stages with an extraction efficiency of 90.2% for Ce. A 556 mg/L Ce solution was used for the scrubbing of La with an efficiency of ≈34%, which required multi stage scrubbing. The study of thermodynamic parameters such as enthalpy, entropy, and Gibbs free energy impart the exothermic and non-spontaneous process. The chemical speciation curves for lanthanum and cerium in the aqueous phase as a function of pH showed that the free La(III) and Ce(III) metal ion species were largely predominate between a pH = 0 and pH = 7.

Solvent extraction and separation of cerium(III) and samarium(III) from mixed rare earth solutions using PC88A

The solvent extraction of cerium(III) and samarium(III) from mixed solutions of all rare earth elements (REEs) except promethium using PC88A (2-ethyl hexyl phosphonic acid mono-2-ethyl hexyl ester), an acidic extractant, was investigated. The effects of aqueous equilibrium pH, various acids (sulfuric acid (H2 SO4), hydrochloric acid (HCl) and nitric acid (HNO3)), initial metal ion concentration and extractant concentration on the solvent extraction of Ce(III) and Sm(III) were systematically studied. From the experimental results, HNO3 and HCl were found to be the preflerred aqueous media for the solvent extraction of both Sm(III) and Ce(III). The most promising experimental conditions of pH, PC88A concentration and metal ion concentration were identified for the extraction of Ce(III) and Sm(III). Separation results showed that H2 SO4 at pH 2 provided the best separation between Sm(III) and Ce(III).

Solvent Extraction of Cerium(III) Using an Aliphatic Malonamide: The Role of Acid in Organic Phase Behaviors

The extraction of Ce(NO3)3 with N,N′-dimethyl N,N′-dibutyl tetradecylmalonamide (DMDBTDMA) in n-dodecane (0.5 M) from acidic (3 M HNO3) and neutral (3 M LiNO3) media was studied by varying the aqueous cerium concentration up to and beyond the point of third phase formation (defined by the Limiting Organic Concentration or LOC). The acidic system showed better Ce(III) extraction (i.e., a higher distribution ratio, DCe), increased water extraction, and also a lower LOC than the neutral system. These observations are consistent with the micellar model, suggesting that acid pre-organizes the organic phase into hydrated reverse micelles that favor Ce(NO3)3 extraction while increasing the attractive potential between aggregates so that third phase formation happens more readily. The findings in this study underline the importance of aggregation in solvent extraction systems and provide the basis for a wider structural study on the effects of acid on the supramolecular structure of the organic phase.

Coordination Reactions in the Extraction of Cerium(IV) and Fluorine(I) by DEHEHP from Mixed Nitric Acid and Hydrofluoric Acid Solutions

The coordination reactions during the solvent extraction of cerium(IV) and fluorine(I) from mixed nitric acid and hydrofluoric acid solutions by di‐(2‐ethylhexyl)‐2‐ethylhexylphosphonate, L (DEHEHP) in heptane have been investigated. The extraction data have been analyzed by graphical methods taking into account all plausible species extracted into the organic phase. Different variables influencing the extraction of Ce(IV), such as the concentrations of nitrate ions, hydrofluroric acid, nitric acid, and extractant have been studied. The results demonstrate that DEHEHP can extract not only Ce(NO3)4 as Ce(NO3)4 · 2L and HF as HF · H2O · L, but both together as Ce(HF)(NO3)4 · L. The extraction equilibrium equations are determined according to slope analysis and IR spectra. The equilibrium constants of the extracted complexes have been calculated, taking into account complexation between the metal ion and inorganic ligands in the aqueous phase and all plausible complexes extracted into the organic phase. It is also shown that boric acid, which was added into the mixed solutions to complex with F(I) is not extracted by DEHEHP, and neither does it affect the extraction of cerium(IV) and HF, nor change the extraction mechanism. Finally, the work points out the basis of separating Ce(IV) and recovering F(I) from nitric acid leach liquors of bastnasite.

SOLVENT EXTRACTION OF CERIUM(IV) AND FLUORINE(I) FROM SULPHURIC ACID LEACHING OF BASTNASITE BY CYANEX 923

The solvent extraction of cerium(IV) and fluorine(I) from simulated sulphuric acid leaching of bastnasite by Cyanex 923 was studied. The results showed that Cyanex 923 can extract not only Ce(IV) as Ce(HSO4)2 (SO4) · 2(Cyanex 923) and F(I) as HF · (Cyanex 923) respectively but them together. The extraction mechanism of Ce(IV) together with F(I) can be related to the formation of Ce(HF)(HSO4)2 (SO4) · 2(Cyanex 923). It was also showed that boric acid in the leaching liquor which was added to chelate F(I) wasn't extracted alone by Cyanex 923 and didn't influence the Cerium(IV) extraction. Boric acid can enhance the extraction of HF and came into organic phase in form of (HF)(H3BO3) · (Cyanex 923). Hydrofluoric acid was extracted from the bastnasite leaching mainly together with Ce(IV). The results also showed that temperature didn't affect the extraction process. IR spectra of purified Cyanex 923 saturated with Ce(IV), HF and H3BO3 were discussed.

LIQUID -LIQUID EXTRACTION OF CERIUM (in) SALICYLATE WITH TRIS (2-ETHYLHEXYL) PHOSPHATE AND TRIBUTYLPHOSPHINE OXTDE

ABSTRACT Tris (2-ethylhexyl) phosphate (TEHP) and Tributylphosphine oxide (TBPO) are proposed as extractants for the solvent extraction of cerium (III) from salicylate media. A critical study of various experimental parameters such as pH, sodium salicylate concentration, TEHP and TBPO concentration and period of equilibration showed that TBPO is a better extractant, due to its higher basicity. Cerium (III) from organic phase is stripped with distilled water and determined by Arsenazo III. The extraction of cerium (III) with both extractants occurs by solvation mechanism and the extractant dependencies of the extractions suggests that the extracted species are solvated metal salicylate salts, Ce (HSal)3. 3TEHP and Ce (HSal)3. 2TBPO respectively. The method permits separation and determination of cerium from binary and synthetic mixtures of commonly associated elements.

The Solvent Extraction of Cerium from Sulphate Solutions - Mini-Plant Trials

The Solvent Extraction of Cerium from Sulphate Solutions - Mini-Plant Trials

In situ electro-oxidation and liquid-liquid extraction of cerium(IV) from nitric acid medium using tributyl phosphate and 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate

The process of in situ electro-oxidation of Ce(III) to Ce(IV) followed by its extraction into the organic phase has been investigated for its applicability in the separation of Ce from nitrate medium. Solvent extraction of cerium from nitric acid after its electro-oxidation to fourth valency state was carried out using tributyl phosphate (TBP) and 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate (KSM-17, equivalent to PC-88A). The efficiency of the extractants at different aqueous phase nitric acid concentrations and different electrode potentials were determined. Various reducing agents such as hydroxylamine hydrochloride, sodium nitrite, ferrous sulphate as well as complexing agents like EDTA, oxalic acid etc, were studied as strippants for the back extraction of cerium from the loaded organic phase. The method developed for the extraction of cerium was further extended to the partitioning of cerium from Ce-Am mixture obtained during the KSM-17 based extraction chromatographic elemental fractionation of PUREX High Activity Waste (HAW) solutions. Recovery of Ce obtained in the extraction experiments by batch as well as by continuous flow organic phase was >95% with good radiochemical purity.

Synergistic solvent extraction of cerium(III) with mixtures of thenoyltrifluoroacetone and dialkyl sulfoxides

Synergism in the extraction of Ce(III) from thiocyanate solutions has been investigated using mixtures of 2-thenoyltrifluoroacetone (HTTA) and bis-2-ethylhexyl sulfoxide (B2EHSO) or di-n-octyl sulfoxide (DOSO) in benzene. A very high synergistic enhancement of the order of 105 has been observed. If a mixture of both dialkyl sulfoxides (B2EHSO+DOSO) is used, an additional synergistic effect is found due to the formation of a mixed, solvated complex when both reagents are added to the metal chelate. These extraction data have been analyzed theoretically with the aid of a computer by taking into account complexation of the metal in the aqueous phase by inorganic ligands and plausible complexation in the organic phase. The equilibrium constants of the various product species have been deduced by non-linear regression analysis.

Solvent extraction of cerium(III) from aqueous thiocyanate solutions by neutral organophosphorus compounds

The extraction of cerium(III) from aqueous solutions containing potassium thiocyanate by tributyl phosphate (TBP) or trioctyl phosphine oxide (TOPO) in kerosene or benzene has been investigated under different conditions. IR spectral studies have been carried out on the organic extracts. The distribution coefficient of cerium(III) for TBP increases monotonously with increasing aqueous thiocyanate concentration. As a result, it is found that the equilibrium equation for the extraction by TBP can be expressed as follows: Ce 3+(aq) + 3NCS −1(aq) ⇌ Ce(NCS) 3(aq), Ce(NCS) 3(aq) + 4TBP(org) ⇌ Ce(NCS) 3·4TBP(org). A similar result was also obtained for the extraction by TOPO, although the extraction efficiency of TOPO is higher than that of TBP. The IR results indicate that the thiocyanate ion coordinates to the cerium ion through the N atom and that the cerium ion combines with the phosphoryl O atom of the extractants.

Solvent Extraction of Cerium(III) with High Molecular Weight Amines

Solvent Extraction of Cerium(III) with High Molecular Weight Amines

Extraction of trace amounts of cerium(III) by oxides of amines and its separation from cerium(IV)

The solvent extraction of cerium(III) from nitric, hydrochloric and sulphuric acid solutions by 4-(5-nonyl)pyridine oxide and trioctylamine oxide in xylene has been studied. The influence of the concentration of the solvents and salting-out agents is described. From the results of partition experiments attempts have been made to deduce the nature of the extracted species. The investigation shows that cerium(III) can be separated from cerium(IV) from very dilute solutions of mineral acids and also from moderate nitric acid media.

Solvent extraction of cerium(III) from ammonium thiocyanate solutions by sulphoxides and their solutions

The extraction of cerium(III) from ammonium thiocyanate solutions by alkyl and aryl sulphoxides, tri-n-octyl phosphine oxide (TOPO), 2-thenoyltrifluoroacetone (TTA), and their solutions has been studied. The species extracted were found to be Ce(SCN)3·4S (where S = di-n-pentyl sulphoxide (DPSO), di-n-octyl sulphoxide (DOSO), diphenyl sulphoxide (DPhSO), or tri-n-octyl phosphine oxide (TOPO)). Synergic effects have been observed which are ascribed to the formation of mixed ligand metal complexes. The extraction of the metal is inversely dependent upon the initial metal concentration and temperature of the system.

Synergistic effect of tri-n-octylamine on the solvent extraction of cerium(III) by thenoyltrifluoroacetone

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynergistic effect of tri-n-octylamine on the solvent extraction of cerium(III) by thenoyltrifluoroacetoneL. Newman and P. KlotzCite this: Inorg. Chem. 1972, 11, 9, 2150–2154Publication Date (Print):September 1, 1972Publication History Published online1 May 2002Published inissue 1 September 1972https://doi.org/10.1021/ic50115a032RIGHTS & PERMISSIONSArticle Views48Altmetric-Citations17LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (610 KB) Get e-Alerts Get e-Alerts