Solvent Extraction Of Thorium Research Articles

Solvent extraction of Thorium from Malaysian xenotime using Tributyl Phosphate (TBP)

Growing interest in environmental concern and vast industrial application makes Thorium popular and widely studies nowadays. In this study, solvent extraction process was done to determine the optimized parameters for the extraction of thorium. Parameters studied are the concentrations (M) of nitric acid (HNO3), percent (%) of Tri-Butyl Phosphate (TBP) in diluent and the volume ratio of acid to organic phase (VA:VO). The mixed rare earth (RE) oxalate powder was dissolved in HNO3 and Thorium elements was extracted using TBP diluted in kerosene. Energy dispersive x-ray fluorescence (ED-XRF) instrument was used to analyze the initial and final concentration of Thorium left in the aqueous solution. From the ED-XRF quantitative values, calculations were made to determine the extraction efficiency of Thorium. In the end of experiment, it is found that the optimized parameters are at 7M HNO3, 20% TBP diluted in kerosene and at VA:VO ratio of 2:3.

Solvent extraction of thorium (IV) from chloride solution using Schiff base and its application for spectrophotometric determination

Thorium (IV) was separated from chloride medium by solvent extraction with Schiff base chelating agent, (E)-4-(2-hydroxyphenyl imino) pentane-2-one (AcPh) that was prepared and characterized by FT-IR, 1H NMR, and elemental analysis. The extraction step was studied with regard to experimental parameters such as diluent type, pH, AcPh concentration, A:O ratio, contact time, temperature and interference of diverse ions on the recovery of thorium ion. The thorium (IV) was then back-extracted into aqueous media containing 0.5 M HNO3 to study the stripping conditions that were A:O ratio, contact time and room temperature. The optimum parameters were applied in the studied sample solution for the spectrophotometric determination at 540 nm with Thoron I. The accuracy of the developed method was tested with B2 standard reference material. Furthermore, the proposed method was successfully applied for the spectrophotometric determination of thorium ions in the geologic sample with good accuracy and precision.

Characterization of reversed micelles formed in solvent extraction of thorium(IV) by bis(2-ethylhexyl) phosphoric acid. Transforming from rodlike to wormlike morphology

Abstract The reversed micelles formed in solvent extraction of thorium(IV) by bis(2-ethylhexyl) phosphoric acid (HDEHP) in n-heptane were studied. IR spectra, dynamic/static light scattering and zero shear viscosity measurements indicated that thorium complexes formed rodlike reversed micelles, and both the size of aggregates and the viscosity of the organic phase increased with the increasing loadage of thorium(IV). The entanglement of reversed micelles resulted in their transformation to wormlike reversed micelles, inducing the very high viscosity of the organic phase. The structural composition of thorium complexes was proposed to be Th(DEHP)3(NO3) according to the results of log -log plot and job method analysis. Furthermore, molecular modeling was employed to clarify the structures of reversed micelles as well as the state of water inside. It was found that the complexes linked together via hydrogen bonding and van der Waals forces and that the existence of NO3 – and H2O improved the stability of reversed micelles.

Solvent extraction of thorium from nitrate medium by TBP, Cyanex272 and their mixture

The extraction behavior of thorium(IV) has been investigated with tri-butyl phosphate (TBP) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272) in kerosene from nitrate medium. The effect of operating variables including time, aqueous phase acidity (pH), extractant concentration and temperature were investigated. This study also examined the synergistic enhancement of the extraction of thorium(IV) from nitrate medium by mixtures of TBP and Cyanex272 for the first time. The optimum synergistic enhancement factor of 3.86 was obtained at a Cyanex272/TBP molar ratio of 1:4.

Solvent extraction of thorium(IV) and rare earth elements with novel polyaramide extractant containing preorganized chelating groups

AbstractBACKGROUNDOligoamides containing intramolecular hydrogen bonds have proved to be excellent extractants for metal cations, but their polymeric counterparts have never been used. Thorium separation from rare earth elements has long been a research subject due to its importance in nuclear energy and metallurgy. In this work a novel polyaramide has been synthesized and investigated for solvent extraction and separation of thorium and rare earths.RESULTSThe synthesized polymer 1 [(C32H46N2O6)n], shows a high extractability of 89.4% towards Th(IV) compared with only 36–48% for rare earths. The optimized pH value for extraction of Th(IV) was 3.97. At C1/CM = 2.0, the extraction for Th(IV) reached 95.1%. When adding NaNO3, the separation of Th(IV) from La(III) is more efficient than that from Eu(III) or Yb(III), especially at higher NaNO3 concentration. Th(IV) can be thoroughly stripped from organic phase at 1.50 mol L‐1 HNO3 concentration.CONCLUSIONDirect condensation of aromatic diamine and diacid led to a novel polyaramide with introverted chelating groups. Selective extraction of Th(IV) with respect to rare earths was observed and the extraction was an endothermic process. The salting‐out agent and C1/CM ratio can affect the separation efficiency. Thus, the polymer 1 may be a potential candidate for separating thorium and rare earths under specified conditions. © 2013 Society of Chemical Industry

Solvent extraction of thorium(IV) using W/O microemulsion

The extraction of thorium(IV) was investigated using two types of W/O microemulsion, one of which was formed by a surface-active saponified extractant sodium bis(2-ethylhexyl) phosphate (NaDEHP) and the other was formed by a mixture of an anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) and an extractant bis(2-ethylhexyl)phosphoric acid (HDEHP) as the cosurfactant. The extraction capacities of the above two systems were higher than that of the HDEHP extraction system. High concentration of NaNO3 showed no influence on the extraction in the NaDEHP based W/O microemulsion system, whilst reduced the extractability in the AOT-HDEHP W/O microemulsion system. The mechanism in acidic condition was demonstrated by the log-log plot method. The structure of the aggregations and the water content in the organic phase after extraction were measured by dynamic light scattering and Karl Fischer water titration, respectively. It was found that NaDEHP based W/O microemulsion broke up after extraction, while AOT-HDEHP W/O microemulsion was reserved.

Determination of optimum process conditions for the separation of thorium and rare earth elements by solvent extraction

The solvent extraction of thorium, some rare earth elements (including lanthanum, cerium and yttrium) and iron was separately investigated in order to determine their optimum separation conditions. The experimental conditions were studied in the concentration range of 0.01–5 M for three acids using Cyanex272, Cyanex302 and TBP (HA) as extractants by Taguchi's method. It was found that Cyanex272 could separate thorium and rare elements more efficiently compared with the conventional process (TBP). The optimum acid concentration in the case of Cyanex272 was determined as 0.5 M HNO 3. The graphical method demonstrated that the composition of the extracted thorium complex was as Th(OH) 2(NO 3)A.HA. Furthermore, the stripping experiments showed that using a mixture of 1 M H 2SO 4 and 2.7 ⁎ 10 −4 M EDTA could provide optimum conditions for the selective stripping of thorium. As a result, thorium was extracted selectively from 0.5 M nitric acid solution of Zarigan ore with the extraction efficiency of 83%. Also yttrium was separated from lanthanides by synergistic mixture containing Cyanex272 and TBP.

Determination of optimum process conditions for solvent extraction of thorium using Taguchi method

Solvent extraction of thorium was studied using Taguchi method. The effect of various parameters such as acid types (sulfuric, nitric, hydrochloric, sulfuric ? nitric) and their concentrations from 0.001 to 4 M, initial thorium concentration (0.0001, 0.001, 0.01, 0.1 M) and solvent type (TBP, D2EHPA, Cyanex921, Cyanex272) in the ranges of 0.001 to 1 M on thorium extraction efficiency were investigated. The maximum extraction of thorium was obtained while 0.001 M hydrochloric acid, 0.001 or 0.01 M thorium and Cyanex272 were used. Under these optimum conditions, the extraction percent and distribution coefficient of thorium were 98.7% and 73.8, respectively. Compared with the hydrochloric aqueous solution, the nitric acid system showed less variation in the extraction of thorium. The proposed process has been applied for the separation of Th(IV), U(VI), La(III), and Ce(III) from synthetic solution same as thorium ores (monazite).

Para‐Substituted 1‐Phenyl‐3‐methyl‐4‐aroyl‐5‐pyrazolones as Chelating Agents for the Synergistic Extraction of Thorium(IV) and Uranium(VI) in the Presence of Various Crown Ethers

Para‐substituted 1‐phenyl‐3‐methyl‐4‐aroyl‐5‐pyrazolones, namely, 1‐phenyl‐3‐methyl‐4‐(4‐fluorobenzoyl)‐5‐pyrazolone (HPMFBP) and 1‐phenyl‐3‐methyl‐4‐(4‐toluoyl)‐5‐pyrazolone (HPMTP) were synthesized and utilized for the extraction of thorium(IV) and uranium(VI) from nitric acid solutions. For comparison, studies have also been carried out with 1‐phenyl‐3‐methyl‐4‐benzoyl‐5‐pyrazolone (HPMBP). The results demonstrate that thorium(IV) and uranium(VI) are extracted into chloroform according to: where HX refers to 1‐phenyl‐3‐methyl‐4‐aroyl‐5‐pyrazolone and K ex,0 denotes the equilibrium constant. The equilibrium constants of the extracted complexes have been calculated by nonlinear regression analysis taking into account the aqueous‐phase complexation of the metal ion with inorganic ligands and all plausible complexes extracted into the organic phase. The equilibrium constants of thorium(IV) and uranium(VI) with various 4‐aroyl‐5‐pyrazolones follow the order HPMFBP > HPMBP > HPMTP, which is in accordance with their pK a values. The synergistic solvent extraction of thorium(IV) and uranium(VI) was also investigated with mixtures of HPMFBP and 18‐crown‐6 (18C6), dicyclohexano‐18‐crown‐6 (DC18C6), dibenzo‐18‐crown‐6 (DB18C6), and benzo‐15‐crown‐5 (B15C5). The complexation strength of Th(PMFBP)4 chelate with crown ethers follows the order B15C5 > 18C6 > DC18C6 > DB18C6. The high extraction efficiency of thorium(IV) with B15C5 can be explained on the basis of “size‐fitting effect.” On the other hand, the complexation strength of UO2(PMFBP)2 chelate with various crown ethers follows the order 18C6 > DC18C6 > B15C5 > DB18C6, which can be explained on the basis of the crown ether basicity sequence and steric effects. Solid complexes of these metal ions with HPMFBP and crown ethers have been isolated and characterized by elemental analyses, IR and 1H NMR spectroscopic techniques to further clarify the nature of the extracted complexes.

Solvent extraction of thorium, lanthanum and europium ions by bis(2-ethylhexyl)phosphoric acid using 2-nitrobenzo-18-crown-6 as ion size selective masking agent

The separation of thorium, lanthanum and europium ions has been improved by acidic extractant bis(2-ethylhexyl)phosphoric acid (DEHPA) in cyclohexane using 2-nitrobenzo-18-crown-6 (NB18C6) as a selective masking agent. The presence of NB18C6 shifts the extraction curve of lanthanide ions versus pH towards higher pH region. NB18C6 was efficient masking agent towards lanthanide ions and a better separation was obtained as compared to 18C6. The stability constants of the lanthanide-crown ether complexes in aqueous phase and the thermodynamic parameters associated with the extraction process were evaluated.

Solvent Extraction of Thorium(IV) by Didodecylphoric Acid

Solvent extraction of Thorium (VI) ion from perchlorate solution using didodecylphosphoric acid, DDPA, in chloroform diluent was studied. The effects of stripping hydrochloric acid concentration, stripping time, extraction time, DDPA concentration, pH, ionic strength, supporting electrolyte and temperature on the extraction processes have been studied. From the distribution coefficient values at different temperatures,the enthalpy, the free energy and the entropy changes associated with the extraction processes were determined. The composition of the complex formed was established to be Th(ClO4)4-nRn(HR)5-n where, n=1 or 2 and (HR)2 represents the dimer of DDPA.

Solvent extraction of thorium (IV) and europium (III) ions by diphenyl-N,N-dimethylcarbamoylmethylphosphine oxide from aqueous nitrate media

The extractive properties of a CMPO-type extractant, diphenyl- N , N -dimethylcarbamoylmethylphosphine oxide (DΦDMCMPO) in dichloromethane, have been investigated towards thorium (IV) and europium (III) ions in nitrate media at 20 °C. The conventional log–log plot analysis of the extraction equilibrium data reveals that the thorium and europium ions are extracted as complexes characterized by a metal/ligand ratio of 1:3 and 1:2, respectively. The effects of solvent, type and concentration of salting-out agent on the extraction abilities of the ligand were studied. The comparative extraction experiments in nitric acid medium showed that DΦDMCMPO exhibits higher efficiencies than tri- n -octylphosphine oxide (TOPO). The influence of temperature on the extraction of the studied ions from 1 M sodium nitrate medium into 1,2-dichloroethane by DΦDMCMPO was tested as a function of temperature in the range 20–40 °C. The distribution ratios of europium ions decrease when raising the temperature, while with thorium ions the opposite phenomenon was observed. From the distribution measurements, thermodynamic parameters such as the free energy (Δ G °), enthalpy (Δ H °) and entropy (Δ S °) changes associated with the extraction processes could be evaluated.

Crown ether as size selective synergist in the solvent extraction of thorium(IV) and uranium(VI) with 3-phenyl-4-(4-fluorobenzoyl)-5-isoxazolone

The synergistic extraction of thorium(IV) and uranium(VI) from nitric acid solutions has been investigated using mixtures of 3-phenyl-4-(4-fluorobenzoyl)-5-isoxazolone (HFBPI) and dicyclohexano-18-crown-6 (DC18C6), dibenzo-18-crown-6 (DB18C6) or benzo-15-crown-5 (B15C5). The results demonstrate that these metal ions are extracted into chloroform as Th(FBPI)4and UO2(FBPI)2with HFBPI alone and as Th(FBPI)4·CE and UO2(FBPI)2·CE in the presence of crown ethers (CE). The equilibrium constants of the above extracted complexes have been deduced by non-linear regression analysis. The addition of a crown ether to the metal chelate system enhances the extraction efficiency and also improves the selectivities significantly between thorium (IV) and uranium(VI). The complexation strength of uranium(VI) with various crown ethers follows the order: DC18C6>B15C5>DB18C6, which can be explained on the basis of crown ether basicity sequence and steric effects. On the other hand, the complexation strength of Th-FBPI chelate with crown ether follows the order: B15C5>DC18C6>DB18C6. The high extraction of thorium(IV) with B15C5 can be explained on the basis of ‘size-fitting effect’. Solid complexes of these metals with 4-acyl-3-phenyl-5-isoxazolones and with mixtures of HFBPI and crown ether have been isolated and characterised by elemental analyses, IR and1HNMR spectroscopic techniques.

Solvent extraction of thorium(IV) ion with N,N,N,N-tetrabutylsuccinylamide from nitric acid solutions

Solvent extraction of thorium(IV) ion with N,N,N,N-tetrabutylsuccinylamide from nitric acid solutions

Extraction of thorium from aqueous nitric acid solution by bis-2-(butoxyethyl ether) (DBC)

The solvent extraction of thorium(IV) (4.3·10−4M) from nitric acid solution by bis-2-(butoxyethyl ether) (butex or DBC) has been studied. It has been investigated as a function of nitric acid, extractant and metal ion concentration. The effect of equilibration time, diverse ions and salting-out agent on the extraction has also been examined. Among anions, fluoride, phosphate, oxalate and perchlorate have reduced the extraction. Cations such as Na(I), K(I), Ca(II), Zn(II), Al(III), Ti(IV), Zr(IV) except Sr(II) and Pb(II) do not interfere in the extraction. The extraction is enhanced upto 97% in three stages at 6M HNO3 having 2.94M NaNO3 as salting-out agent. The extraction is found to be independent of thorium concentration in the range studied (4.3·10−4–4.3·10−2M). The temperature (18–45°C) has an adverse effect on the extraction. A 1% solution of ammonium bifluoride is found to be a good stripping solution and recovery of thorium is >98%.

Solvent extraction of thorium(IV) with dibutyldithiophosphoric acid in various organic solvents

The extraction of thorium(IV) from perchlorate solutions with di-n-butyldithiophosphoric acid (HBudtp) in various organic solvents occurs through an ion exchange mechanism. The extracted species in the organic phase is an eight-coordinate complex Th(Budtp)4. The higher values of the distribution ratio obtained in HBudtp-benzene-water system than in HBudtp-n-butanol-water system are explained by higher solubility of the complex species in nonpolar solvents. The position of the extraction curves in the pH-range lower than 0.7 reduces the complexation of thorium(IV) with Budtp− in the aqueous phase and also the hydrolysis process.

Solvent extraction of thorium (IV) with dialkyldithiophosphoric acids

Solvent extraction of thorium (IV) from aqueous solution with dialkyldithiophosphoric acids (RO)2P(S)SH, (abbreviated Hdtp) in different organic solvents shows that the chain length in Hdtp significantly influence the magnitude of the distribution ratio. The diluent effect and the influence of the inorganic anion present in the aqueous phase was investigated in the Th — di (2-ethyl-hexyl) dithiophosphoric acid (HEhdtp) extraction system. The treatment of the partition data shows that the extraction of Th(IV) in benzene, cyclohexane, chloroform, carbon tetrachloride and n-butanol from perchlorate, chloride and nitrate media occurs via an ion-exchange mechanism. Inorganic anions present in the aqueous phase do not participate in the formation of the extracted species but influence the magnitude of the distribution ratios.

Solvent extraction of thorium from mixed organic — aqueous nitric acid media by try-n-octylphosphine oxide

The extraction equilibria of Th in tri-n-octylphosphine oxide (TOPO)−HNO3−H2O systems have been investigated in the absence and presence of water-miscible alcohols and acetone. The influence of TOPO concentration in an inert diluent (toluene) and the concentration of nitric acid and the water-miscible additives have been systematically examined. The slopes of the log-log plots of DTh vs. the TOPO concentration (up to 0.02M) are found to be close to 3 over a wide range of polar phase compositions leading to a coordination number of 11 for Th. The DTh values were determined as a function of the concentration of uranyl nitrate in the aqueous phase, while the effect of additives was also examined in the absence and presence of uranyl nitrate in the polar phase. The results show that at TOPO concentrations above about 2.5 · 10−3 M (about 1%) in toluene, polymerization of the solvent occurs.

Solvent Extraction of Thorium with Liquid Cation Exchanger (Versatic 10)

Solvent Extraction of Thorium with Liquid Cation Exchanger (Versatic 10)

Solvent Extraction of Thorium with Versatic 911

Abstract The distribution of Th(IV) between an aqueous solution and a high-molecular weight synthetic carboxylic acid, Versatic 911 (Shell Co. Ltd., London), diluted with benzene was studied. Thorium was quantitatively extracted at pH 4.0–4.9 from 0.1 M acetic acid solution. The study of the effects of pH, extractant concentration, metal concentration, diluent, and contact time on the extraction of thorium(IV) was performed. The metal/Versatic 911 ratio was determined in the extracted species and the experimente showed that the ratio is 1:4. The extraction dependence upon acetate ion concentration was also examined. Thorium(IV) was separated from magnesium, calcium, strontium, barium, manganese, cobalt, nickel, zinc, cadmium, lanthanum, praseodymium, neodymium, samarium, gadolinium, and mercury. The proposed methods are very simple, rapid, and fairly selective, and can be carried out both at micro and macro levels. Important quantitative separations of thorium from synthetic mixtures were also carried out.