Solvent Extraction Separation of Beryllium(ll) from Aluminum(lll) by Cyanex 921 (TOPO)

ABSTRACT

Cyanex 921, a neutral extractant, has been used for the extraction of beryllium(II)from basic media and employed for the separation of beryllium(II) in the presence of aluminum(III). Cyanex 921 diluted in cyclohexane extracted beryllium(II) in the 8–10 pH range and aluminum(III) between 4–5 pH. The selectivity of beryllium(II) over aluminum(III) was high in the 8–10 pH range. The extracted beryllium(II) was stripped with 0 M NaOH without any significant loss of the ligand while loaded aluminum(III) was stripped with 2 M HC1. The extractability of beryllium(II) and aluminum(III) was also studied separately as a function of pH, temperature, equilibration time, and stripping ability with NaOH, KOH, HCI, HNO₃, H₂SO₄, and HCIO₄. Based on these results, a sequential method was developed for the separation of beryllium(II) from aluminum(III).     

Solvent Extraction of Gallium (III) from Basic Sodium Aluminate Solution by Alkanoyl Oxines

Abstract

Alkanoyl oxines have been used for the extraction of gallium from basic solution, especially for the selective recovery of gallium in the presence of excess aluminum from Bayer process sodium aluminate liquor. 5-Alkanoyl-8-hydroxyquinolines (R.CO.Ox), where R is the alkyl group C₁₃H₂₇ (myristoyl), C₁₅H₃₁ (palmitoyl), and C₁₇H₃₅ (stearoyl) were synthesized by the Fries rearrangement from the corresponding acid chloride and sodium oxinate using AlCl₃ as catalyst. The synthesized alkanoyl oxines were capable of extracting Ga into kerosene or chloroform at a pH around 13; the selectivity of Ga over A1 was high at this pH. The extracted Ga could be stripped into the aqueous phase acidified with HCl without significant loss of the ligand. The extractability of Ga was studied as a function of pH, temperature, time, metal concentration, phase separation acid (undecanol) concentration; and the strippability as a function of HCl concentration. Based on these results, a sequential procedure for the selective separation of Ga from alkaline Bayer process liquor has been developed.     

Extraction of Lanthanides(III) and Am(III) by Mixtures of Malonamide and Dialkylphosphoric Acid

Abstract

N,N′‐dimethyl‐N,N′‐dioctylhexylethoxymalonamide, DMDOHEMA, and di‐n‐hexylphosphoric acid, HDHP, are the extractants of reference for the French DIAMEX–SANEX process for the separation of trivalent actinide ions from the lanthanide ions. In this work, the extraction of Eu³⁺ and Am³⁺ by the two extractants, alone or in mixtures, has been investigated under a variety of experimental conditions. The two cations are extracted by HDHP as the M(DHP · HDHP)₃ complexes with an Eu/Am separation factor of ～10. With DMDOHEMA, Eu³⁺ and Am³⁺ are extracted as the M(NO₃)₃(DMDOHEMA)₂ disolvate species with an Am/Eu separation factor of ～2. The metal distribution ratios measured with a mixture of the two reagents indicated that almost all lanthanides are extracted equally well. The extraction of Eu³⁺ and Am³⁺ by HDHP‐DMDOHEMA mixtures exhibits a change of extraction mechanism and a reversal of selectivity taking place at ～1 M HNO₃ in the aqueous phase. Below this aqueous acidity, HDHP dominates the metal extraction by the mixture, whereas DMDOHEMA is the predominant extractant at higher aqueous acidities. Some measurements indicated apparent modest antagonism between the two extractants in the extraction of Eu³⁺ and synergism in the extraction of Am³⁺. These data were interpreted as resulting from the formation in the organic phase of mixed HDHP‐DMDOHEMA species containing two HDHP and five DMDOHEMA molecules.     

Solvent Extraction and Separation of Gallium(III) using Hexaacetato Calix(6)Arene

Gallium(III) was extracted at pH 3.5 by equilibrating eight min with 10 mL of 0.0001 M acetyl derivative of calix(6)arene in xylene. Gallium(III) was stripped quantitatively with 0.1 N hydrochloric acid and determined spectrophotometrically with 0.01% PAR at 510 nm. The nature of the extracted species was determined from the log-log plots and its stoichiometry was confirmed by numerical treatment to experimental data. The IR analysis of Ga(III) loaded organic phase was also studied. The conformational change of reagent during complex formation was studied from the ¹H NMR treatment. The temperature dependence of the extraction equilibrium and metal loading capacity of the reagent was also evaluated. The proposed method was successfully applied for the extraction and separation of multicomponent mixtures, synthetic mixtures, and binary and ternary separation of gallium from the associated elements. The results obtained were reproducible and accurate.     

Extraction of Rhodium Chlorocomplexes and Acid through a Supported Liquid Membrane of Kelex 100

Abstract

The supported liquid membrane (SLM) technique was employed to effect the separation of Rh Chlorocomplexes from hydrochloric acid solutions. The liquid membrane consisted of an alkylated 8-hydroxyquinoline extractant (Kelex 100), tridecanol, and kerosene. The nonaquated Rh complexes were transported through the membrane upon ion-pair formation with protonated Kelex 100 molecules. The ion-pair was then dissociated at the strip side of the membrane, releasing the Rh values. The main driving force for this transport process was the acid activity gradient across the membrane. The permeation of acid and water, which were cotransported with the Rh complexes, was partially prevented upon addition of NaCl to the strip phase. However, the accumulation of Cl^? ions in the strip phase, in turn, slowed down the extraction of Rh. Optimum Rh extraction performance was obtained when a feed of 2.5 M HC1 and a strip solution of pH 1 were used. Under these conditions the membrane was found to be very stable for at least a period of 72 hours (maximum period tested) while the rate of extraction was found to be 2.8 × 10^?6 mol·s^?1·m^?2.     

Process Intensification via Liquid Emulsion Membrane Technique in Extraction and Enrichment of Rhodium (III) from Chloride Media

A liquid emulsion membrane (LEM) system as a tool for process intensification has been studied for rhodium recovery using di-2-ethylhexylphosphoric acid (D2EHPA) as a metal carrier and Monemul 80 as a surfactant, dissolved in liquid paraffin. The various process parameters affecting the LEM process, such as extractant, surfactant, and strip phase concentrations, the speed of agitation, the batch contact time, and the treat ratio have been experimentally investigated to get better insight into the process. Perchloric acid was found to be a better stripping agent in the LEM process. It was observed that the extraction of Rh (III) can be significantly more in the absence of a water repelling agent. The maximum enrichment of Rh (III) in the internal phase obtained was 4.3 times with feed phase pH adjusted to 6, perchloric acid (1.5 mol/dm³), and contact time of 15 min. A mass transfer model to predict the performance of the LEM system was used and found to fit well with the experimental data.     

Synergistic Solvent Extraction of Lanthanides (III) with Mixtures of Tetraphenylmethylenediphosphine Dioxide and Picrolonic Acid from HCl Solutions

The solvent extraction of lanthanides(III) from hydrochloric acid solutions into the organic phase containing neutral bidentate extractant tetraphenylmethylenediphosphine dioxide (L) and picrolonic acid (HP) has been studied. A considerable synergistic effect was observed in the presence of HP in the organic phase containing neutral bidentate organophosphorus ligand. The extraction equilibrium was investigated and the equilibrium constants were calculated. It was found that the lanthanide(III) ions are extracted from weak acidic solutions as LnP₃L and LnP₃L₂ complexes. The mixture L–HP offers higher extraction efficiency toward Ln(III) than mixtures of L with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 or picric acid.     

Synthesis of Bismuth(III)Neodecanoate and Its Application to Poly(Vinyl Chloride) as a Thermal Stabilizer

The bismuth(III)neodecanoate (Bi(Ne)₃) was synthesized via the method of co-reaction of bismuth oxide, neodecanoic acid, and acetic anhydride and then characterized by Fourier transform infrared spectroscopy (FTIR) and elemental analysis (EA). The effect of Bi(Ne)₃ as a thermal stabilizer on poly(vinyl chloride) (PVC) was assessed by thermal aging test, Congo red test, conductivity measurement, and thermogravimetric analysis, respectively. The results showed that Bi(Ne)₃ significantly provided PVC with a good initial color and long-term stability. Bi(Ne)₃ played a role in improving the stabilizing efficiency of PVC through absorbing hydrogen chloride (HCl) and displacing labile chlorine atoms in PVC molecular chains.     

The Transport of Copper(II) through Hollow Fiber Renewal Liquid Membrane and Hollow Fiber Supported Liquid Membrane

Abstract

In this paper, hollow fiber renewal liquid membrane (HFRLM) and hollow fiber supported liquid membrane (HFSLM) were used to simultaneously remove and recover copper(II) from aqueous solutions, and the transport performance of these two techniques were compared under the similar conditions for the system of CuSO₄ +D2EHPA in kerosene +HCl. The results showed that the HFRLM process was more stable than the HFSLM process. The HFRLM process had a higher overall mass transfer coefficient than that of HFSLM process in single-pass experiments. These were because the renewal effect of the liquid membrane layer could reduce the mass transfer resistance of the lumen side and replenish the loss of the membrane liquid in the HFRLM process. The transport results were better in the HFRLM process than that in the HFSLM process with recycling experiments. Therefore, HFRLM technique is a promising method for simultaneous removal and recovery of heavy metal from aqueous solutions.     

Process Intensification: Extraction of Chromium(VI) by Emulsion Liquid Membrane

Abstract

Electroplating is one of the important processes involved in surface finishing and metal deposition for better life of articles and for decoration. Chromium(VI) is the most commonly used metal for electroplating. Thus, the waste water of such industries contains Chromium(VI) ions. Emulsion Liquid Membrane (ELM) separation technique provides a potentially powerful technique for the removal of Chromium(VI) ions from the waste water. In the present study, the effect of different parameters such as pH, different carriers concentration, synergistic effect caused by a mixture of two appropriate carriers concentration, effect of electrostatic surface potential and effects of composition of a dilute polymer solution; which will intensify the extraction efficiency of Chromium(VI); are systematically investigated using Aliquat 336 and tri‐n‐octyl amine as extractant, sorbitan mono‐oleate (span 80) as surfactant, kerosene as membrane phase and sodium hydroxide as stripping solution.     

Synergistic Extraction of Lanthanides (III) with Mixtures of TODGA and Hydrophobic Ionic Liquid into Molecular Diluent

The extraction of lanthanides(III) from aqueous nitric acid solutions with N,N,N’,N’-tetra(n-octyl)diglycolamide (TODGA) and with mixtures of TODGA and the hydrophobic ionic liquid (IL) [C₄mim][Tf₂N] into 1,2-dichloroethane (DCE) has been investigated. The extraction efficiency of Ln(III) ions was greatly enhanced by the addition of a small amount of IL to an organic phase containing TODGA. The synergistic effect comes from the higher hydrophobicity of Ln(III) extracted species formed by TODGA and the weakly coordinating Tf₂N^? anions compared with those formed by TODGA and NO₃^? ions as the counter-anions. The partition of Tf₂N^? anions between the organic and aqueous phases is the dominant factor governing the extractability of lanthanides(III) with mixtures of TODGA and [C₄mim][Tf₂N]. The extraction of Ln(III) from aqueous nitric acid solutions by TODGA alone and its mixtures with [C₄mim][Tf₂N] into DCE can be described on the basis of the solvation extraction mechanism. However, in the extraction system with added [C₄mim][Tf₂N], the partition of Tf₂N^? between two immiscible phases and the interaction between HTf₂N and TODGA in the organic phase should be taken into account. Possible reasons of the antagonistic effect in the TODGA–[C₄mim][Tf₂N] extraction system are discussed.     

Development and Demonstration of Americium (III)-Europium (III) Separation Using Diglycolamic Acid

The extraction behavior of Eu(III) and Am(III) in a solution of bis(2-ethylhexyl)diglycolamic acid (HDEHDGA) in n-dodecane (n-DD) from citric acid (CA) medium was studied as a function of various parameters. The extraction increased with increase of pH, reached a maximum at pH 2 followed by decrease. The stripping behavior of Eu(III) and Am(III) from the loaded organic phase was studied by using a solution of diethylenetriaminepentaacetic acid (DTPA) and CA. The conditions needed for the efficient separation of Am(III) from Eu(III) were optimized. Based on the optimized conditions, the feasibility of separating Am(III) from Eu(III) present in CA feed solution was investigated in a 20- stage mixer-settler. Quantitative extraction of Eu(III) and Am(III) in 0.1 M HDEHDGA/n-DD was achieved in 3–4 stages, whereas the selective back extraction of Am(III) was achieved in ～20 stages upon contacting the loaded organic phase with a stripping formulation composed of DTPA-CA at pH 1.5. The results confirmed the possibility of using diglycolamic acid for the separation of trivalent actinides from the chemically similar lanthanides, which is indeed necessary for transmutation of minor actinides present in high-level liquid waste (HLLW).     

Extraction of U(VI), Th(IV), and Lanthanides(III) from Nitric Acid Solutions with CMPO-Functionalized Ionic Liquid in Molecular Diluents

The extraction of microquantities of U(VI), Th(IV), and lanthanides(III) from nitric acid solutions with CMPO-functionalized ionic liquid 1-[3[[(diphenylphosphinyl)acetyl]amino]propyl]-3-tetradecyl-1H-imidazol-3-ium hexafluorophosphate, CMPO-FIL(I) in molecular organic diluents has been studied. The effect of HNO₃ concentration in the aqueous phase and that of extractant concentration in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes was determined. CMPO-FIL(I) demonstrates greater extraction ability towards Ln(III) than its neutral CMPO analog, diphenylphosphorylacetic acid N-nonylamide. This inner synergistic effect increases with a decreasing organic diluent polarity. The partition of CMPO-FIL(I) between the equilibrium organic and aqueous phases is the dominant factor governing the extractability of Ln(III) ions in the extraction system.     

Extraction separation of Ir(III) and Rh(III) with Cyanex 923 from chloride media: a possible recovery from spent autocatalysts

Liquid–liquid extraction of Ir(III) and Rh(III) with Cyanex 923 from aqueous hydrochloric acid media has been studied. Quantitative extraction of Ir(III) was observed in the range of 5.0–8.0 mol dm^?3 HCl with 0.1 mol dm^?3 Cyanex 923, while Rh(III) was extracted quantitatively in the range of 1.0–2.0 mol dm^?3 HCl with 0.05 mol dm^?3 Cyanex 923 in toluene along with 0.2 mol dm^?3 SnCl₂. The Ir(III) was back extracted with 4.0 mol dm^?3 HNO₃ quantitatively from the organic phase while Rh(III) was stripped with 3.0 mol dm^?3 HNO₃. The extraction of Rh(III) with Cyanex 923 was not quantitative without use of SnCl₂. However in the extraction of Ir(III) a negative trend was observed in the presence of SnCl₂. Varying the temperature of extraction showed that the extraction reactions of both the metal ions are exothermic in nature, and the stoichiometric ratio of Ir(III)/Rh(III) to Cyanex 923 in organic phase was found to be 1:3. The methods developed were applied to the recovery of these metal ions from a synthetic solution of similar composition to that from leaching of spent autocatalysts in 6.0 mol dm^?3 HCl. © 2002 Society of Chemical Industry     

Ion Imprinted Polymer Solid Phase Extraction (IIP‐SPE) for Preconcentrative Separation of Erbium(III) From Adjacent Lanthanides and Yttrium

Abstract

Erbium(III) ion imprinted polymer (IIP) materials were prepared by photochemical polymerization of the ternary complex, Erbium(III)—5,7‐dichloroquinoline‐8‐ol‐4‐vinylpyridine, with methyl methacrylate (functional monomer) and ethylene glycol dimethacrylate (crosslinking monomer) in the presence of 2,2′‐azobisisobutyronitrile (initiator). The synthesis was carried out in 2‐methoxy ethanol (porogen) medium and the resultant material was filtered, dried and powdered to form unleached polymer particles. The imprint ion (erbium(III)) was removed by stirring the above particles with 6 mol/l HCl to obtain leached polymer particles. These leached particles are termed erbium(III) ion imprinted polymer (IIP) particles as it selectively rebind erbium(III) ions. Non‐imprinted/control polymer (CP) particles were similarly prepared without the imprint ion. CP and unleached and leached IIP particles were characterized by XRD, microanalysis, and UV‐visible spectrophotometric studies. Various parameters that influence ion imprinted polymer—solid phase extraction such as pH, weight of polymer particles, preconcentration time, elution time, eluent volume, and aqueous phase volume were varied and optimal conditions for each parameter for quantitative enrichment of erbium(III) were established. The selectivity coefficients of erbium(III) ion over Y, Dy, Ho and Tm were compared with separation factors reported for two of the best liquid—liquid extractants viz. di‐2‐ethylhexyl phosphoric acid and 2‐ethylhexyl‐ethylhexyl phosphate.     

Highly efficient and fast adsorption of Au(III) and Pd(II) by crosslinked polyethyleneimine-glutaraldehyde

An adsorbent (PEI-GA) is prepared by crosslinking polyethyleneimine with glutaraldehyde. PEI-GA shows outstanding adsorption performance towards Au(III) and Pd(II). PEI-GA presents large adsorption capacity towards Au(III) in a wide application pH range from 1 to 9. The adsorption capacities of PEI-GA for Au(III) and Pd(II) at 25°C reach 2575 and 497 mg/g, respectively. Au(III) and Pd(II) can be adsorbed completely within 10 min for 8.3 mg/L Au(III) and 20 min for 9.7 mg/L Pd(II). The adsorption equilibrium time required for 523.9 mg/L Au(III) and for 565.6 mg/L Pd(II) is 2 and 9 h, respectively. The Sips model is the most suitable to describe the adsorption isotherms which leads to more realistic adsorption capacities for both metals. PEI-GA also exhibits high selectivity and repeatability towards Au(III) and Pd(II). The adsorption mechanism involves redox, chelation coordination, and electrostatic interactions for Au(III), and coordination and electrostatic interactions for Pd(II).     

叔胺萃取分离钴(II)、铁(II)

研究了不必预先氧化二价铁,直接用叔胺从氯化物溶液中萃取分离钴(II)、铁(II)的新方法. 考察了不同改性剂对叔胺萃取钴(II)、铁(II)的影响以及各种因素对钴(II)、铁(II)萃取、洗涤及反萃的影响. 提出了用叔胺萃取分离钴(II)、铁(II)的最佳工艺参数.     

Extraction of Hexavalent Chromium from Aqueous Stream by Emulsion Liquid Membrane (ELM)

Emulsion Liquid Membrane (ELM) separation technique is an effective procedure for the removal of Chromium (VI) ions from the wastewater stream. In the present study, the effect of changes of different parameters such as the pH of feed solution, the stirring speed, and the emulsification time, carrier concentration, surfactant concentration, the effect on the presence of other metal ions, are systematically investigated. The membrane phase consists of kerosene with hexane as diluant, Aliquat 336 as extractant, sorbitan mono-oleate (span 80) as surfactant. 1 (N) Sodium hydroxide is the stripping solution. Results show that by the ELM process, 90% Cr(VI) can remove successfully in optimum condition from feed.