Highly Copper(II) Ion‐Selective Transport Through Liquid Membrane Containing N,N′‐bis(salicylidene)‐1,2‐phenyldiamine

Abstract

N,N′‐bis(salicylidene)‐1,2‐phenyldiamine was synthesized for examining their ability to extract and transport Cu²⁺ through a liquid membrane. By using hydrazine sulfate and potassium thiocyanate as reducing agent and acceptor respectively in the receiving phase at the optimum pH of 1.5, the amount of copper transported across the liquid membrane after 3.5 hours was 96%. The selectivity and efficiency of copper transport from aqueous solution containing various metal ions were investigated.     

Extraction of Palladium(II) from Nitric Acid Solutions with 1‐Benzoyl‐3‐[6‐(3‐benzoyl‐thioureido)‐hexyl]‐thiourea

The extraction of palladium (II) from HNO₃ solutions with 1‐Benzoyl‐3‐[6‐(3‐benzoyl‐thioureido)‐hexyl]‐thiourea (Ia) and several monodentate thiourea derivatives in 1,2‐dichloroethane has been studied. The effect of HNO₃ concentration in the aqueous phase and that of the extractant in the organic phase on the Pd(II) extraction is considered. The stoichiometry of the extracted complexes has been determined. The increasing number of thioamide groups in the molecule of Ia increases its extraction efficiency towards Pd(II). The potentialities of a polymeric resin impregnated with compound Ia for selective extraction of Pd(II) from nitric acid solutions are demonstrated.     

Selective and Efficient Liquid Membrane Transport of Thallium (III) Ion by Potassium‐dicyclohexyl‐18‐crown‐6 as Specific Carrier

Abstract

Potassium‐dicyclohexyl‐18‐crown‐6 was used as a selective and efficient carrier for the uphill transport of thallium (III) ion as [TlCl₄]^? complex ion through a chloroform bulk liquid membrane. By using oxalate anion as a metal ion acceptor in the receiving phase, the amount of thallium (III) transported across the liquid membrane after 120 min was 96±2%. The selectivity and efficiencies of thallium transport from aqueous solutions containing Cu²⁺, Zn²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Co³⁺, Mn²⁺ _, Cr³⁺, Mg²⁺, Ca²⁺, K⁺, Na⁺, and Fe³⁺ ions were investigated. In the presence of Na₃PO₄ (0.01 M) at pH=3 as a suitable precipitation agent in the source phase, the interfering effect of Pb²⁺ ion were diminished drastically.     

Extraction Properties of 6,6′‐Bis‐(5,6‐dipentyl‐[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridinyl (C5‐BTBP)

Abstract

The extraction of americium(III) and europium(III) into a variety of organic diluents by 6,6′‐bis‐(5,6,‐dipentyl‐[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridinyl (C5‐BTBP) has been investigated. In addition to determining the stoichiometry for the extraction, the dependence of extraction on contact time and temperature was also studied. The resistance of the ligand to gamma irradiation and the possibility to recycle the organic phase after stripping were tested to determine how the molecule would perform in a radiochemical process. Different organic diluents gave different extraction results, ranging from no extraction to distribution ratios of over 1000 for americium(III). In 1,1,2,2‐tetrachloroethane, the extraction and separation of americium from europium and the extraction kinetics were good; a separation factor above 60 was obtained at equilibrium, ～5 min contact time. The extraction capabilities are adequate for C5‐BTBP to be used in a process for separating trivalent actinides from lanthanides. However, C5‐BTBP is susceptible to radiolysis (americium extraction decreases ～80% after a dose of 17 kGy) and may not be the best choice in the processing of spent nuclear fuel. Nonetheless it is a useful starting point for further development of this type of molecule. It could also prove useful for analytical scale separations for which radiolytic instability is less important.     

Extraction of Actinides with Different 6,6′‐Bis(5,6‐Dialkyl‐[1,2,4]‐Triazin‐3‐yl)‐[2,2′]‐Bipyridines (BTBPs)

Abstract

The extraction of Am(III), Th(IV), Np(V), and U(VI) from nitric acid by 6,6′‐bis(5,6‐dialkyl‐[1,2,4]‐triazin‐3‐yl)‐[2,2′]‐bipyridines (C2‐, C4‐, C5‐, and CyMe₄‐BTBP) was studied. Since only americium and neptunium extraction was dependent on the BTBP concentration, computational chemistry was used to explain this behavior. It has been shown that the coordination of the metal played an important role in forming an extractable complex into the organic phase, thus making it possible to extract pentavalent and trivalent elements from tetravalent and hexavalent elements. This is very important, especially because it shows other possible utilizations of a group of molecules meant to separate the actinides from the lanthanides. In addition, the level of extraction at very low or no BTBP concentration was explained by coordination chemistry.     

Separation of Actinides(III) from Lanthanides(III) in Simulated Nuclear Waste Streams using 6,6′‐Bis‐(5,6‐dipentyl‐[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridinyl (C5‐BTBP) in Cyclohexanone

Abstract

An extraction system comprising 6,6′‐bis‐(5,6‐dipentyl‐[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridinyl (C5‐BTBP) dissolved in cyclohexanone was investigated. The main purpose of this investigation was to extract and separate actinides(III) from lanthanides(III), both of which are present in the waste from the reprocessing of spent nuclear fuel. The system studied showed high distribution ratios for the actinides(III) and a high separation factor between actinides and lanthanides (SF_Am/Eu around 150). The extraction kinetics were fast with equilibrium being reached in 5 minutes. The effects of temperature on the extraction and the stoichiometry of the extracted complex were investigated. The extraction of californium(III) was studied and it was found that the BTBP molecule has a higher affinity for californium than for americium (SF_Cf/Am around 4). This system could be used to separate actinides(III) from lanthanide fission products with high efficiency, if used in conjunction with a pre‐equilibrium step.     

Para‐substituted 1‐Phenyl‐3‐methyl‐4‐aroyl‐5‐pyrazolones as Selective Extractants for Vanadium(V) from Acidic Chloride Solutions

Abstract

Para‐substituted 4‐aroyl derivatives of 1‐phenyl‐3‐methyl‐5‐pyrazolones (HX), 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 examined with regard to the extraction behavior of multivalent metal ions such as magnesium(II), aluminum(III), titanium(IV), vanadium(V), chromium(III), manganese(II), iron(II), and iron(III) that are present in titania waste chloride liquors. For comparison, studies have also been carried out with 1‐phenyl‐3‐methyl‐4‐benzoyl‐5‐pyrazolone (HPMBP). The results demonstrate that vanadium(V) and iron(III) are extracted into chloroform with 4‐aroyl‐5‐pyrazolones as VO₂X · HX and FeX₃, respectively. On the other hand, magnesium(II), aluminum(III), titanium(IV), chromium(III), manganese(II), and iron(II) were not found to be extracted into the organic phase. The equilibrium constants of vanadium(V) and iron(III) with various 4‐aroyl‐5‐pyrazolones follow the order HPMFBP>HPMBP>HPMTP, which is in accordance with their pKa values. The selectivity between vanadium(V) and iron(III) increases with increasing hydrochloric acid concentration. Further, it is clear from the results that iron(III) is not getting extracted above 1.0 mol dm^?3 hydrochloric acid solution. The electronic and IR spectra of the extracted complexes of vanadium(V) and iron(III) were used to further clarify the nature of the extracted complexes. The potential of these reagents for the selective extraction and separation of vanadium(V) from titania waste chloride liquors has also been discussed.     

An Investigation into the Extraction of Americium(III), Lanthanides and D‐Block Metals by 6,6′‐Bis‐(5,6‐dipentyl‐[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridinyl (C5‐BTBP)

Abstract

The tetradentate ligand (C₅‐BTBP) was able to extract americium(III) selectively from nitric acid. In octanol/kerosene the distribution ratios suggest that stripping will be possible. C₅‐BTBP has unusual properties and potentially offers a means of separating metals, which otherwise are difficult to separate. For example C₅‐BTBP has the potential to separate palladium(II) from a mixture containing rhodium(III) and ruthenium(II) nitrosyl. In addition, C₅‐BTBP has the potential to remove traces of cadmium from effluent or from solutions of other metals contaminated with cadmium. C₅‐BTBP has potential as a reagent for the separation of americium(III) from solutions contaminated with iron(III) and nickel(II), hence offering a means of concentrating americium(III) for analytical purposes from nitric acid solutions containing high concentrations of iron(III) or nickel(II).     

Recovery of Plutonium(IV) from Aqueous Solutions Using Emulsion Liquid Membrane Containing 2‐Ethylhexyl Phosphonic Acid Mono‐2‐Ethylhexyl Ester as Ion Transporter

Abstract

An emulsion liquid membranes (ELMs) containing 2‐ethylhexyl phosphonic acid mono‐2‐ethylhexyl ester (H₂A₂) was tested for the extraction of plutonium(IV) from aqueous nitrate solutions of different compositions. Span 80 was used as the surface‐active agent and a mixture of 0.05 mol dm^?3 HNO₃+0.3 mol dm^?3 H₂C₂O₄ was used as the internal phase. Influence of some important experimental parameters such as exterior phase nitric acid concentration, ionic impurities in the exterior phase, concentration of H₂A₂ in ELM phase, and organic solvents on the ELM permeation process were systematically studied. The maximum efficiency of Pu extraction among group of experiments was 98% with permeability coefficient=0.508 min^?1, and the corresponding concentration factor of Pu in the receiving phase was ca. 10. The stability of the emulsions was tested in the presence of different organic solvents and at different concentrations of Span 80 in LM phase. The extractions of Pu by ELM from actual and simulated waste solutions as well as in presence of some added ionic impurities were investigated. Rate of Pu extraction by ELM was studied at different treatment ratios and under repeat extractions by the same emulsion. The repeat extraction experiments showed that a concentration factor of more than 80 for Pu could be achieved.     

Ion‐Exchange Separation of Pu from Macro Concentration of Th in HNO3 Medium

Abstract

Sorption behavior of Th and Pu from anion‐ as well as cation‐exchange resin was investigated from nitric acid medium by both batch and column methods. The anion‐exchange studies involved anionic nitrate complexes of Pu⁴⁺ and Th⁴⁺ sorbed onto DOWEX 1x4 resin (50–100 mesh), and the cation‐exchange studies involved the sorption of Pu³⁺ and Th⁴⁺ onto BIORAD AG 50Wx8 (50–100 mesh) or DOWEX 50Wx4 (50–100 mesh) resin. The batch data gave a separation factor (K _d,Pu/K _d,Th) of 22 for the anion‐exchange method and 0.017 for the cation‐exchange method at 3 and 2 M HNO₃, respectively. A two‐stage ion‐exchange separation method was developed for the quantitative separation of Pu (8 g/L) from a macro amount of Th (200 g/L) in nitric acid medium. The first step involved the quantitative sorption of plutonium from the mixture while about 90% of Th could be washed in 6 column volumes. The plutonium, eluted (as Pu³⁺) using 0.5 M HNO₃ + 0.2 M hydrazinium nitrate (HN) + 0.2 M hydroxyl ammonium nitrate (HAN), and the residual (～10%) Th were subsequently loaded onto a cation‐exchange column in the second step. Greater than 99% Pu was recovered with 2 M HNO₃ (in ～8 column volumes) containing 0.2 M HN + 0.2 M HAN. The final elution of thorium from the cation‐exchange column was achieved in about 6 column volumes of 1 M α‐hydroxy isobutyric acid. A (Pu, Th)O₂ fuel scrap sample was dissolved in 16 M HNO₃ containing 0.005 M HF and was used subsequently as the feed for the anion‐exchange column. The eluted Pu was subsequently loaded onto a cation‐exchange column for final purification. The recovery of plutonium and thorium was found to be >99% and >98%, respectively, while the respective decontamination factors were estimated to be 215 and 292.     

Characterization of Extraction of Chromatographic Materials Containing Bis(2‐ethyl‐1‐hexyl)Phosphoric Acid, 2‐Ethyl‐1‐Hexyl (2‐Ethyl‐1‐Hexyl) Phosphonic Acid,and Bis(2,4,4‐Trimethyl‐1‐Pentyl)Phosphinic Acid

Abstract

This work describes the uptake of a wide range of metal ions, including alkaline earths, transition metals, post‐transition metals, lanthanides and actinides, from acidic nitrate and chloride media on extraction chromatographic resins prepared from three different acidic organophosphorus compounds: bis(2‐ethyl‐1‐hexyl) phosphoric acid (HDEHP), 2‐ethyl‐1‐hexyl(2‐ethyl‐1‐hexyl)phosphonic acid, (HEH[EHP]) and bis(2,4,4‐trimethyl‐1‐pentyl)phosphinic acid (H[DTMPP]). The data is plotted in a format allowing for the easy comparison of the uptake of all metal ions under a given condition. Additionally, examples of several novel separations using the three extraction chromatographic materials are discussed.     

6,6′‐Bis(5,5,8,8‐tetramethyl‐5,6,7,8‐tetrahydro‐benzo[1,2,4]triazin‐3‐yl) [2,2′]bipyridine,an Effective Extracting Agent for the Separation of Americium(III) and Curium(III) from the Lanthanides

Abstract

The extraction of americium(III), curium(III), and the lanthanides(III) from nitric acid by 6,6′‐bis(5,5,8,8‐tetramethyl‐5,6,7,8‐tetrahydro‐benzo[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridine (CyMe₄‐BTBP) has been studied. Since the extraction kinetics were slow, N,N′‐dimethyl‐N,N′‐dioctyl‐2‐(2‐hexyloxy‐ethyl)malonamide (DMDOHEMA) was added as a phase transfer reagent. With a mixture of 0.01 M CyMe₄‐BTBP+0.25 M DMDOHEMA in n‐octanol, extraction equilibrium was reached within 5 min of mixing. At a nitric acid concentration of 1 M, an americium(III) distribution ratio of approx. 10 was achieved. Americium(III)/lanthanide(III) separation factors between 50 (dysprosium) and 1500 (lanthanum) were obtained. Whereas americium(III) and curium(III) were extracted as disolvates, the stoichiometries of the lanthanide(III) complexes were not identified unambiguously, owing to the presence of DMDOHEMA. In the absence of DMDOHEMA, both americium(III) and europium(III) were extracted as disolvates. Back‐extraction with 0.1 M nitric acid was thermodynamically possible but rather slow. Using a buffered glycolate solution of pH=4, an americium(III) distribution ratio of 0.01 was obtained within 5 min of mixing. There was no evidence of degradation of the extractant, for example, the extraction performance of CyMe₄‐BTBP during hydrolylsis with 1 M nitric acid did not change over a two month contact.     

Synergistic Solvent Extraction and Separation of Lanthanide(III) Ions with 4‐Benzoyl‐3‐Phenyl‐5‐Isoxazolone and the Quaternary Ammonium Salt

The solvent extraction of the lanthanide(III) ions (without Pm) with a 4‐benzoyl‐3‐phenyl‐5‐isoxazolone(HPBI) alone and in the presence of the quaternary ammonium salt Aliquat 336 in perchlorate form (QClO₄) in C₆H₆ was investigated by the slope analysis method. The composition of the extracted species was determined as Ln(PBI)₃ and Q[Ln(PBI)₄] (Q⁺ is the quaternary ammonium salt cation). The values of the equilibrium constant were calculated. Synergistic effects were found for all lanthanide metals when they were extracted with a binary mixture of HPBI and QClO₄. The influence of the synergistic agent on the extraction process has been discussed. The parameters of the extraction process were determined. The separation factors between adjacent metals were evaluated.     

Effect of Anions on the Extraction of Lanthanides (III) by N,N′‐Dimethyl‐N,N′‐Diphenyl‐3‐Oxapentanediamide

Abstract

The extraction of microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y by N,N′‐dimethyl‐N,N′‐diphenyl‐3‐oxapentanediamide (DMDPhOPDA) in 1,2‐dichloroethane from aqueous media containing ClO₄ ^?, PF₆ ^?, (CF₃SO₂)₂N^? anions or by DMDPhOPDA in 1,2‐dichloroethane in the presence of 1‐butyl‐3‐methylimidazolium bis[(trifluoremethyl)sulfonyl]imide ([C₄mim][Tf₂N]) and 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([C₄mim][PF₆]) from HNO₃ solutions has been studied. The effect of HNO₃ concentration in the aqueous phase and that of the extractant concentration in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes has been determined. The addition of HPF₆ and (CF₃SO₂)₂NH or their salts to the aqueous HNO₃ or HCl solutions leads to an enchancement of lanthanides (III) extraction by DMDPhOPDA. A considerable synergistic effect was observed in the presence of ionic liquids (IL) in the organic phase containing DMDPhOPDA. This effect is connected with the hydrophobic nature of the IL anion. The distribution of ILs between the equilibrium organic and aqueous phases can govern the extractability of lanthanides (III) in DMDPhOPDA‐IL systems.     

C,N‐Pyridylpyrazole‐Based Ligands: Synthesis and Preliminary Use in Metal Ion Extraction

Abstract

The synthesis of new N‐donor pyridylpyrazole ligands with a functionalized arm is described. The complexation capabilities of these compounds towards bivalent metal ions (Hg²⁺, Cd²⁺, Pb²⁺, Cu²⁺, and Zn²⁺) and alkali metal ions (K⁺, Na⁺, and Li⁺) were investigated using the liquid‐liquid extraction process. The percentage limits of extraction were determined by atomic absorption measurements.     

Synergistic Extraction of Lanthanides(III) by Mixtures of N‐p‐Methoxybenzoyl‐N‐phenylhydroxylamine and 1,10‐Phenanthroline

Abstract

We conducted a study on the equilibrium extraction behavior of the trivalent lanthanide ions (M³⁺), La, Pr, Eu, Ho, and Yb, from tartrate aqueous solutions into chloroform solutions containing N‐p‐methoxybenzoyl‐N‐phenylhydroxylamine (Methoxy‐BPHA, HL) and 1,10‐phenanthroline (phen). The synergistic species extracted was found to be {ML₂(phen) (HL)}⁺(1/2)Tar^2?, where Tar^2? is tartrate ion. The extraction constants were calculated. The extraction separation behavior and extractability of lanthanides are discussed in comparison with the self‐adducted chelate, ML₃(HL)₂, which was extracted in the absence of phen, and synergistic extraction by mixtures of other extractants such as 2‐thenoyltrifluoroacetone, and neutral donors.     

Ion‐selective Imprinted Superporous Monolith for Cadmium Removal from Human Plasma

Abstract

Molecular recognition based separation systems have received much attention because of their high selectivity for target molecules. Molecular imprinting has been recognized as a promising technique for the development of affinity adsorbents. Molecularly imprinted polymers (MIP) are easy to prepare, stable, inexpensive, and capable of molecular recognition. Cadmium is a carcinogenic and mutagenic element. The limit value of cadmium in blood should be no higher than 50 pg/L when exposure to cadmium is unavoidable in industry. There is no specific treatment available for acute or chronic metal poisoning. Besides supportive therapy and hemodialysis, metal poisoning is often treated with commercially available chelating agents including EDTA and dimercaprol. However, there is histopathological evidence for increased toxicity in animals when these agents are utilized. The aim of this study is to prepare superporous ion‐imprinted polymer monolith which can be used for the selective removal of Cd²⁺ ions from Cd²⁺‐overdosed human plasma. N‐methacryloly‐(L)‐cysteinemethylester (MAC) was chosen as the complexing monomer. In the first step, MAC synthesized by using methacryloyl chloride and cysteine. Cd²⁺ was complexed with MAC monomer and the Cd²⁺‐imprinted poly(HEMA‐MAC) monoliths were synthesized by bulk polymerization. After that, Cd²⁺ ions were removed by 0.1 M thiourea and 0.1 M HNO₃ solutions, respectively. Cd²⁺‐imprinted poly(HEMA‐MAC) monoliths had a specific surface area of 226.8 m²/g and the swelling ratio was determined to be 76%. According to the elemental analysis results, monoliths contain approximately 58.3 µmol/g of MAC. The maximum adsorption capacity for Cd²⁺ ions was 26.6 µmol/g of the dry weight of monolith. The adsorption capacity decreased significantly from 23.25 µmol/g to 3.08 µmol/g polymer with the increase of the flow‐rate from 1 mL/min to 4 mL/min. The Cd²⁺‐imprinted poly(HEMA‐MAC) monolith could be used many times without decreasing their adsorption capacities significantly.