Extraction Of Cerium Research Articles

A rational approach to processing cerium-containing raw materials

A method for the online control of cerium extraction from rare-earth raw materials based on the oxidation of its trivalent ions with hydrogen peroxide, followed by the precipitation of hydroxide and additional acid treatment to remove trivalent impurities has been considered.

Subsequent separation and selective extraction of thorium (IV), iron (III), zirconium (IV) and cerium (III) from aqueous sulfate medium

Regarding to their presence as an important constituent in some ores such as monazite, this work aims for selective solvent extraction of thorium (IV), zirconium (IV), iron (III) and cerium (III) from aqueous sulfate medium using different basic and acidic extractants. To elucidate the extractability of these elements, different effective parameters were studied such as contact time, pH value, extractant concentration and the diluents type. In a single element system, Th (IV) was extracted by the primary amines (octylamine and tert.octylamine) and the acidic extractnts [di-(2-ethylhexyl) phosphoric acid (D2EHPA) and (bis(2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272))]. Moreover, secondary amine (N-methylaniline) is effective for Fe (III) extraction while, the primary amines are suitable for Zr (IV) extraction. Ce (III) can be extracted with the primary amines and D2EHPA. In a mixed elements system, Th (IV) was extracted firstly with Cyanex 272 (65 %) atpH1 followed by the extraction of Fe(III) with N-methylaniline (95 %), then Zr (IV) was precipitated atpH2.5 (84 %) whileCe(III) remains in the final aqueous phase.

Research on extraction of cerium from rare-earth metals concentrate solutions by electrochemical and extraction methods

In order to extract cerium from rare-earth metals (REM) recovered from Russian raw materials, the following modern domestic equipment was selected: OXITRON-58L-O2 diaphragm electrolyzer manufactured by LLC «Delfin Aqua» with the purpose of Ce(III) to Ce(IV) oxidation; EC-10FA centrifugal extractor manufactured by LLC «LIT» with the purpose of Ce(IV) extraction from the sum of REM. These units were used in the studies performed to identify conditions that would lead to cerium oxidation to a 4-valent state with the electrochemical method as well as to recover and clean Ce(IV) from rare-earth metals with the solvent extraction method. The experiments were performed with standardized test solutions of cerium nitrate and process solutions obtained using loparite concentrate from the Solikamsk Magnesium Plant. The conditions were identified and equipment operation modes were designed in order to enable the chosen electrolyzer model to achieve a degree of cerium oxidation in REM process solutions over 99 % at power consumption below 0,8 kW/h per 1 kg of CeO2, and extract cerium from REM concentrate solution using the laboratory cascade of 20 centrifugal extractors with further production of 99,6 % pure CeO2.

Solvent Extraction and Spectrophotometric Determination of Cerium(IV) by Using <i>o</i>-Methoxy Phenylthiourea as an Analytical Reagent

Solvent Extraction and Spectrophotometric Determination of Cerium(IV) by Using <i>o</i>-Methoxy Phenylthiourea as an Analytical Reagent

Cerium Separation from Light Rare Earth Concentrate by Liquid-Liquid Extraction

This work presents an investigation of solvent extraction parameters in order to obtain high purity cerium from a mixture containing other rare earths elements, as an alternative to oxidation and selective precipitation or dissolution. The study was carried out using a sample of sulfuric liquor obtained from the leaching of monazite rich in light rare earth elements (La, Ce, Pr, Nd) provided by INB (Indústrias Nucleares do Brasil S.A.). Experiments were carried out in chloridric, nitric and sulfuric media. The nitric and hydrochloric solutions were prepared by precipitation of the REE from the sulfuric liquor as rare earths oxalate, calcining the precipitate and dissolving it with nitric or hydrochloric acid. The separation of cerium was investigated in its trivalent and tetravalent forms. The parameters investigated were: type and concentration of extractant, type and amount of the oxidizing agent, liquor acidity, and volumetric ratio between organic and aqueous phases. The preference of the organic phase to extract cerium in its oxidized form (IV) over the other rare earths elements was confirmed, allowing the obtainment of a high purity cerium solution. The best results were achieved in nitric medium, with cerium in its tetravalent form, using cationic extractants (P507 or D2EHPA) and a mixture of potassium persulfate and silver chloride as oxidizing agents, yielding over 99% of cerium extraction with over 99% of purity.

Thermodynamic investigation of extraction of cerium(III) by tributyl phosphate from phosphoric acid solutions

A mechanism of extraction of cerium by tributyl phosphate (TBP) from phosphate solutions using model and production solutions containing, %: 26–28 P2O5, 1,2–2,8 SO3, 0,3–0,8 CaO, 0,1–0,4 Al2O3, 0,3–0,4 Fe2O3, and 0,09–0,1 REM(NO3)3. A model solution of phosphoric acid corresponded to the industrial solution of extraction phosphoric acid (EPA) by the content of P2O5 and Ce(NO3)3 and value of pH (0,6). Dependences of extraction parameters on the TBP concentration in o-xylene and concentration of nitrate ions introduced by magnesium and calcium nitrates, which are used as a salting-out agent, are found. The composition of the extracted organic complex of cerium Ce(H2PO4)(NO3)2·TBPorg is determined. A constant of extraction equilibrium and the Gibbs energy of extraction are calculated. It is concluded by the results of the experiment that it is unreasonable to use TBP to extract Ce from phosphoric acid systems without introducing a considerable amount of the salting-out agent.

A study of cerium extraction by TBP and TODGA using a rotating diffusion cell

Abstract For the study of the coupled interfacial-mass transfer kinetics of, inter alia, TBP, TODGA, CyMe4-BTBP and CyMe4-BTPhen based solvent extraction processes, a new rotating diffusion cell (RDC) apparatus has been established at Lancaster University. RDC studies of Ce(IV)/TBP and Ce(III)/TODGA extraction systems have been undertaken in order to improve the understanding of the chemical and kinetic processes involved. In each case, an interesting dependency on local hydrodynamics at the solution phase boundary with results suggesting that the organic extractant molecules migrate into the aqueous phase in order to capture Ce.

Thermodynamic investigation into extraction of cerium(III) by tributyl phosphate from phosphoric acid solutions

A mechanism of extraction of cerium by tributyl phosphate (TBP) from phosphate solutions using model and production solutions containing, %: 26–28 P2O5, 1.2–2.8 SO3, 0.3–0.8 CaO, 0.1–0.4 Al2O3, 0.3–0.4 Fe2O3, and 0.09–0.1 REE(NO3)3 is investigated. The model solution of phosphoric acid corresponds to the industrial solution of extraction phosphoric acid (EPA) by the content of P2O5 and Ce(NO3)3 and value of pH (0.6). Dependences of extraction parameters on the TBP concentration in o-xylene and concentration of nitrate ions introduced by magnesium and calcium nitrates, which are used as a salting-out agent, are found. The composition of the extracted organic complex of cerium Ce(H2PO4)(NO3)2TBPorg is determined. A constant of extraction equilibrium and the Gibbs energy of extraction are calculated. It is concluded by the results of the experiment that it is unreasonable to use TBP to extract Ce from phosphoric acid systems without introducing a considerable amount of the salting-out agent.

Synergistic extraction of cerium(III)-oxinates in presence of tributyl phosphine oxide

Synergistic extraction of cerium(III)-oxinates in presence of tributyl phosphine oxide

Flotation recovery of rare-earth metal compounds from dilute aqueous solutions

The possibility of flotation extraction of lanthanum and cerium (III) compounds from diluted sulfate solutions was shown by using finely dispersed solid solutions of different radical phosphine oxide in paraffin. Optimal conditions for conducting the flotation have been determined. The effect of electrolyte additions on the process efficiency was studied. In addition, the mechanism of interaction of rare earth metal compounds with flotation collector was proposed.

Extraction of cerium (IV) using di-n-butylsulfoxide in chloroform from nitric acid and determination with arsenazo (III) as chromogenic Reagent

A new and advantageous extraction procedure was developed for extraction of cerium (IV) from nitric acid with di- n -butylsulfoxide (DBSO) in perchloric acid. The extracted Ce (IV) was determined spectrophotometrically using 0.01 % solution of arsenazo-III in 3Mper-chloric acid. Various parameters such as equilibration time, metal ion concentration, effect of temperature and diverse ions on the extraction of the Ce (IV) were established. U (VI), Th (IV) and Pb (II) interfere whereas only phosphate and fluoride suppress the extraction among anions. The stoichiometric composition of the cerium complex withDBSO was determined by slope analysis and found to be 1:4. The process of extraction was found to be exothermic. Deionized water was the most appropriate solvent for back extraction of cerium. This method is easier and more sensitive than many of the reported procedures. KEYWORDS Cerium, extraction, DBSO, perchloric acid, arsenazo-II.

Electrochemical Extraction of Cerium by Forming Ce-Zn Alloys in LiCl-KCl Eutectic on W and Liquid Zn Electrodes

The electrochemical formation of Ce-Zn alloys in LiCl-KCl eutectic was systematically investigated by cyclic voltammetry (CV), square wave voltammetry (SWV) and open circuit chronopotentiometry (OCP). Due to the decrease of Ce activity in the metal phase of formed Ce-Zn alloys, the deposition potential of Ce(III) at a liquid Zn electrode was found to be 0.64 V more positive than that on an inert W electrode. The co-reduction behaviors of Ce(III) and Zn(II) ions were also studied in LiCl-KCl eutectic. Signals associated with six and nine CexZny intermetallic compounds were detected by CV and OCP techniques, respectively. In addition, potentiostatic electrolyses were carried out to extract Ce at a liquid Zn electrode in LiCl-KCl-CeCl3 melt and on a W electrode in LiCl-KCl-CeCl3-ZnCl2 melt, respectively. Deposited samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). The results showed that intermetallic compound CeZn11 was prepared on both the inert W electrode and liquid Zn electrode.

Electrochemical extraction of cerium and formation of Al-Ce alloy from CeO2 assisted by AlCl3 in LiCl-KCl melts

This work presents an electrochemical extraction of cerium and synthesization of Al-Ce alloy in LiCl-KCl melts on Mo and Al electrodes by chlorination of CeO2 using AlCl3 at 873 K. The cyclic voltammogram on Mo electrodes in LiCl-KCl-CeO2 melt showed no obvious reduction wave other than the reduction of Li(I). After the addition of AlCl3, the signals of the reaction of Ce(III)/Ce(0) and the synthesization of Al-Ce and Al-Li alloys were investigated by cyclic voltammetry, square-wave voltammetry, open-circuit chronopotentiometry and chronopotentiometry. These results indicated that AlCl3 can chloridize CeO2 and that it is possible to extract cerium and form Al-Ce and Al-Li-Ce alloys in LiCl-KCl-CeO2-AlCl3 melts. According to potentiostatic electrolysis, only the Al4Ce layer coated the Al electrodes. According to galvanostatic electrolysis, Al-Ce (Al4Ce, Al3Ce, and Al92Ce8), Al2Li3, and Al phases were formed on Mo electrodes, and the content of cerium in the Al-Li-Ce alloys was more than 17 wt%.

Synergistic extraction and separation of lanthanum (III) and cerium (III) using a mixture of 2-ethylhexylphosphonic mono-2-ethylhexyl ester and di-2-ethylhexyl phosphoric acid in the presence of two complexing agents containing lactic acid and citric acid

Lanthanum and cerium were synergistically extracted and separated in chloride medium using a mixture of 2-ethylhexylphosphonic mono-2-ethylhexyl ester (HEHEHP) and di-2-ethylhexyl phosphoric acid (D2EHPA) with lactic acid (LA) and citric acid (H3cit) as the complexing agents. Synergistic effects were observed for the extraction of La and Ce with the mixed extractant; and the maximum synergistic coefficients were obtained at XHEHEHP=0.8. A maximum βCe/La of 8.88 and the maximum extraction capacity of 53.48g/L were obtained in the presence of two complexing agent. Organo–Ce complexes in organic phases were examined based on FT-IR, 1H, and 31P NMR spectra. The cation-exchange mechanism and coordination effect between Ce and P=O ligands were verified. Results showed that the mixture system in the presence of complexing agents exhibited a higher extraction efficiency and selectivity during the extraction and separation of adjacent rare earths.

Electrochemical extraction of cerium from CeO2 assisted by AlCl3 in molten LiCl-KCl

This work concerns the co-reduction behaviors of Ce(III) with Al(III) ions and electrochemical extraction of cerium from cerium dioxide in molten LiCl-KCl at the temperature of 773K. Cyclic voltammetry (CV), square wave voltammetry (SWV), chronopotentiometry (CP), and open circuit chronopotentiometry (OCP) techniques were employed to investigate the electrochemical behaviors of Ce(III) and Al(III) ions on molybdenum (Mo) electrode. The results revealed Ce(III) and Al(III) cations can be co-reduced at the surface of the Mo electrode by forming different kinds of Ce-Al alloys. Finally, potentiostatic electrolysis at different deposition potentials on Al plate electrodes was also performed to prepare Ce-Al alloys. The deposition products were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS). It was found that only one intermetallic compound (Al11Ce3) could be formed at the deposition potential of -1.6V and two intermetallic compounds (Al11Ce3 and Al3Ce) could be formed at the potential of -1.9V. When the deposition potential was negative than -2.1V, cerium-rich alloy (AlCe) could be obtained on the surface of the Al electrode.

Extraction of niobium, yttrium, and cerium from a low-grade niobium-bearing ore by roasting (NH4)2SO4-Na2SO4-H2SO4 system

A novel process of extracting niobium, yttrium, and cerium from a low-grade niobium-bearing ore by the roasting (NH4)2SO4-Na2SO4-H2SO4 system was experimentally studied. The influences of various factors, such as roasting temperature, roasting time, mass ratio of agents-to-ore and particle size fraction on the extraction of valuable metals were comprehensively investigated. It is found that the roasting Na2SO4-H2SO4 system is effective to extract the niobium, yttrium, and cerium. The obtained optimum conditions for the extraction of Nb, Y, and Ce are roasting temperature of 300 °C, roasting time of 3 h, mass ratio of Na2SO4:H2SO4:Ore of 0.5:1.0:1.0, and particle size fraction of −74 μm (~95 %). Under the optimum condition, the maximum recovery of Nb, Y, and Ce can reach 90.53 %, 92.15 %, and 98.04 %, respectively. All the results generated from this study will provide the fundamentals for Nb, Y, and Ce extraction from a niobium-bearing ore with low-grade.

Comparison of hollow fiber membrane and solvent extraction techniques for extraction of cerium and preparation of ceria by stripping precipitation

AbstractBACKGROUNDThe extraction of cerium by hollow fiber supported liquid membrane using tri‐octyl methyl ammonium chloride (TOMAC) as mobile carrier was studied and the result was compared with solvent extraction data. The effect of different parameters such as pH, flow rates, extractant concentration, metal ion concentration and strip solution concentration on cerium extraction was investigated.RESULTSThese parameters were optimized for maximum cerium flux and were found to be: pH 1.0, 0.1 mol L−1 TOMAC, 290 mL min−1 feed solution flow rate, 150 mL min−1 strip solution flow rate and 0.9 mol L−1 H2SO4 as strip solution. The parameters were also optimized for solvent extraction study. The number of stages and Aqueous:Organic (A:O) ratio for extraction and stripping were determined from McCabe–Thiele diagrams. The extracted species was determined to be (R3NCH3)2Ce(SO4)3. The selective separation of cerium in presence of various other metal ions such as iron, copper, zinc, cobalt, nickel and manganese using a hollow fiber supported liquid membrane (HFSLM) was carried out and the separation factor values were found to be in the order α Ce/Fe <αCe/Cu < αCe/Mn < αCe/Zn < αCe/Co < αCe/Ni. Finally highly pure (99.99%) CeO2 was prepared by stripping precipitation with oxalic acid and thermal decomposition at 900°C for 1 h.CONCLUSIONThe efficiency of hollow fiber supported liquid membrane was greater than that of solvent extraction for the extraction of cerium for the present system. © 2014 Society of Chemical Industry

Extraction of lanthanum and cerium from Indian red mud

Laboratory-scale experiments were conducted to recover lanthanum and cerium from Indian red mud in sulfuric acid medium. The method includes acid leaching of red mud pulp and subsequent liquid–liquid extraction of the leached metals with different organic extractants, in order to establish the technical feasibility of extraction and separation simultaneously. Maximum recovery of lanthanum (99.9%) was recorded with 3M H2SO4 at ambient (35°C) temperature, S/L ratio of 10g/L and agitation rate of 200rpm in 1h time. While 99.9% cerium recovery was achieved at 75°C and solid/liquid ratio of 10g/L in 3M H2SO4. Significant specificity for complete extraction of lanthanum, cerium and scandium by Cyanex 301 was noted as compared to the solvents such as DEHPA and Cyanex 272.

Preparation of sol–gel materials doped with ionic liquid and extractant for cerium(III) extraction

Silica materials (ILDEHPASGs) consisting of ionic liquids and di-(2-ethylhexyl)phosphoric acid (DEHPA) for Ce(III) extraction was prepared by a sol–gel method using the hydrophobic ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim]PF6) as porogen and solvent medium. The ILDEHPASGs were characterized by scanning electron microscopy, Brunauer–Emmett–Teller surface area, Fourier transform infrared, and thermogravimetric analyses. The results indicated the doping of DEHPA and [C8mim]PF6 in ILDEHPASG-3 would evidently affect the formation of porous structure of sol–gel materials. ILDEHPASG-3 also possessed more channels and macropores than the blank sorbent; the surface area and pore volume of ILDEHPASG-3 were 409 m2 g−1 and 0.444 cm3 g−1, respectively. [C8mim]PF6 and DEHPA were only physically confined or entrapped in the growing covalent silica network rather than chemically bound to the inorganic matrix. The majority of [C8mim]PF6 and DEHPA were stably immobilized in the gel. Then, the effects of contact time and pH were determined. The results showed the sorption of Ce(III) strongly depended on the contact time and pH, and ILDEHPASGs had high sorption ability for Ce(III). The results were analyzed by both Langmuir and Freundlich adsorption isotherm models, and the latter was found to give a better fit.

Design a novel optical adsorbent for simultaneous ultra-trace cerium(III) detection, sorption and recovery

This study aims to develop a highly selective optical mesoporous conjugate adsorbent for efficient optical detection, sorption and extraction of cerium (Ce(III)) from waste effluents. The adsorbent was prepared by synthesizing of 4-tert-Octyl-4-((phenyl)diazenyl)phenol and subsequently successfully immobilized onto mesoporous silica monoliths. The data revealed that the conjugate adsorbent was efficiently detected and adsorbed the ultra-trace Ce(III) ions from aqueous solutions. Therefore, the present adsorbent based on novel ligand modified optical conjugate adsorbent offered a simple technique without using sophisticated instruments for Ce(III) detection, sorption and recovery systems. The solution pH was played an important role for detection and sorption but the present adsorbent worked well in acidic pH region at 3.50. Some important experimental conditions such as dosage of adsorbent, initial Ce(III) concentration, contact time, selectivity, reversibility and kinetics performances have been investigated. The detection limit and maximum sorption capacity of the adsorbent for Ce(III) at optimum conditions was 0.18μg/L and 192.31mg/g, respectively. In addition, the adsorbent was reversible and kept remaining functionality to reuses in several cycles after extraction/elution process without significant deterioration in its original performances. Therefore, the design of optical conjugate adsorbent has a great potential to be used in efficient, selective and simultaneous Ce(III) detection, sorption and extraction from waste and can be used of nuclear power plants wastewaters treatment effectively. Large-scale studies are recommended to confirm these promising results of the laboratory scale.