SOLVENT EXTRACTION EQUILIBRIA OF GALLIUM (III) WITH ACIDIC ORGANOPHOSPHORUS COMPOUNDS FROM AQUEOUS NITRATE MEDIA

A comparative investigation on the solvent extraction equilibria of gallium(III) from aqueous nitrate media was conducted with three kinds of acidic organophosphorus compounds, di (2-ethylhexyl) phosphoric acid (D2EHPA), 2-ethylhexyl 2-ethyl-hexylphosphonic acid (EHEHPA) and di (2,4,4'-trimethylpentyl) phosphinic acid (DTMPPA), in toluene at 303 K. It was found that gallium(III) is extracted as 1:4 metal:reagent complexes with D2EHPA and EHEHPA and as a 1:3 complex with DTMPPA in the region of low loading ratio while it is extracted as 1:3 complexes with all reagents at high loading ratio. The extraction equilibrium constants with these extractants were evaluated for the former complexes as follows: K_e = 2.3xl0^-2, 8.5xl0^-3 and 1.3xl0^-4 for D2EHPA, EHEHPA and DTMPPA respectively.     

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).     

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).     

Novel Diglycolamic Acid Functionalized Iron Oxide Particles for the Mutual Separation of Eu(III) and Am(III)

Iron oxide (Fe₃O₄) particles functionalized with diglycolamic acid (Fe-DGAH) were synthesized and characterized by TG-DTA, X-Ray diffraction,¹H NMR, and scanning electron microscopy (SEM). The extraction behavior of Am(III) and Eu(III) in Fe-DGAH was studied from dilute nitric acid medium to examine the feasibility for the mutual separation of trivalent actinides and lanthanides using Fe-DGAH. For this purpose, the effect of various parameters such as the duration of equilibration and concentrations of europium, nitric acid, and diethylenetriaminepentaacetic acid (DTPA) in the aqueous phase on the distribution ratio (K_d) of Am(III) and Eu(III) was studied. The conditions needed for the efficient separation of Am(III) from Eu(III) were optimized using DTPA. The distribution ratio of ?10⁴ mL/g was obtained for both Am(III) and Eu(III) at pH 3, and it decreased with an increase in the concentration of nitric acid. However, a separation factor of Eu(III) over Am(III) of ?150 was achieved in the presence of DTPA. Rapid sorption of metal ions in the initial stages of equilibration followed by the establishment of equilibrium occurred within 2 h. The sorption data were fitted to the Langmuir adsorption model, and the apparent europium sorption capacity was determined to be ?50 mg/g. The study indicated the feasibility of using Fe-DGAH particles for magnetic separation of Eu(III) from Am(III) with high separation factors.     

Extraction Behavior of the Synergistic System 2,6‐ bis ‐(Benzoxazolyl)‐4‐ Dodecyloxylpyridine and 2‐Bromodecanoic Acid Using Am and Eu as Radioactive Tracers

Abstract

In this study, the extraction properties of a synergistic system consisting of 2,6‐bis‐(benzoxazolyl)‐4‐dodecyloxylpyridine (BODO) and 2‐bromodecanoic acid (HA) in tert‐butyl benzene (TBB) have been investigated as a function of ionic strength by varying the nitrate ion and perchlorate ion concentrations. The influence of the hydrogen ion concentration has also been investigated. Distribution ratios between 0.03–12 and 0.003–0.8 have been found for Am(III) and Eu(III), respectively, but there were no attempts to maximize these values. It has been shown that the distribution ratios decrease with increasing amounts of ClO₄ ^?, NO₃ ^?, and H⁺. The mechanisms, however, by which the decrease occurs, are different. In the case of increasing perchlorate ion concentration, the decrease in extraction is linear in a log–log plot of the distribution ratio vs. the ionic strength, while in the nitrate case the complexation between nitrate and Am or Eu increases at high nitrate ion concentrations and thereby decreases the distribution ratio in a non‐linear way. The decrease in extraction could be caused by changes in activity coefficients that can be explained with specific ion interaction theory (SIT); shielding of the metal ions, and by nitrate complexation with Am and Eu as competing mechanism at high ionic strengths. The separation factor between Am and Eu reaches a maximum at ～1 M nitrate ion concentration. Thereafter the values decrease with increasing nitrate ion concentrations.     

Extraction Behavior of Nickel(II) using some of the BTBP‐Class Ligands

Abstract

Recently the BTBP‐family of solvating ligands have been studied for their ability to separate trivalent actinides from lanthanides. Five of the BTBPs were evaluated for their ability to extract nickel(II) from aqueous nitrate media into cyclohexanone. It was shown by both solvent extraction and X‐ray diffraction experiments that the BTBPs are capable of forming both 1:1 and 1:2 complexes with nickel(II). When the BTBP concentration is low the nickel distribution ratio is governed by the formation of the nickel/BTBP complex while at higher BTBP concentrations the partitioning of the nickel complex between the two phases dictates the nickel distribution ratio.     

Thermodynamic and Spectroscopic Studies on Am(III) and Eu(III) in the Extraction System of N,N,N',N'-Tetraoctyl-3-Oxapentane-1,5-Diamide in n-Dodecane/Nitric Acid

Abstract

Thermodynamic parameters (ΔG, ΔH, and ΔS) for the extraction of trivalent f-elements, M(III) (M = Am, Eu), with N,N,N',N'-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) were determined in nitric acid/n-dodecane extraction system. The extraction of M(III) with TODGA was more exothermic than those with octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) and dihexyl-N,N-diethylcarbamoylmethyl phosphonate (DHDECMP). The difference in ΔH between the extractants was attributed to the difference in the binding mode between them, i.e. tridentate (TODGA) and bidentate (CMPO and DHDECMP). In addition, from the results of luminescence lifetime measurement, it was found that the inner-sphere of extracted Eu(III) was dehydrated completely, and occupied by TODGA and/or NO₃ ^?.     

Synthesis and Characterization of 6,6ˊ-bis(1-(2-ethylhexyl)-1H-1,2,3-triazol-4-yl)-2,2ˊ-bipyridine (EH–BTzBP) for Actinide/Lanthanide Extraction and Separation

A new N-donor extractant, 6,6ˊ-bis(1-(2-ethylhexyl)-1H-1,2,3-triazol-4-yl)-2,2ˊ-bipyridine (EH-BTzBP), was synthesized and tested for Am(III)/Ln(III) extraction and separation. EH-BTzBP in combination with 2-bromohexanoic acid (as lipophilic anion source) selectively extracts Am(III) from acidic solutions (HNO₃ ≤ 0.1M) with Am(III)/Eu(III) separation factors of about 70. Phase transfer kinetics is rapid, back-extraction of metal ions posed no issues, and there is no evidence of ligand degradation by acid hydrolysis or contact with hydrogen peroxide (which simulates some effects of radiolysis).     

Modelling of the Am(III) – Cm(III) kinetic separation effect observed during metal ion extraction by bis-(1,2,4)-triazine ligands

The kinetic separation effect was observed leading to a separation factor for Am(III) over Cm(III) as high as 7.9 by using 2,9-bis-(1,2,4-triazin-3-yl)-1,10-phenantroline (BTPhen) ligands in our recent study. In an attempt to explain the observed tendencies, several kinetic models were tested. A model based on mass transfer as the rate-controlling process was found to best describe the kinetic data and allowed to simulate the dependence of Am/Cm separation factor on time. The calculated values of the overall mass-transfer coefficients confirmed that the observed kinetic effect was caused by the different rates of Am(III) and Cm(III) extraction. This kinetic separation phenomenon and its explanation paves the way for potential new approaches to separation of metal ions with very similar properties, such as the adjacent minor actinides Am(III) and Cm(III).     

Advances in electrochemical Fe(VI) synthesis and analysis

Hexavalent iron species (Fe(VI)) have been known for over a century, and have long-time been investigated as the oxidant for water purification, as the catalysts in organic synthesis and more recently as cathodic charge storage materials. Conventional Fe(VI) syntheses include solution phase oxidation (by hyphchlorite) of Fe(III), and the synthesis of less soluble super-irons by dissolution of FeO₄ ²⁻, and precipitation with alternate cations. This paper reviews a new electrochemical Fe(VI) synthesis route including both in situ and ex situ syntheses of Fe(VI) salts. The optimized electrolysis conditions for electrochemical Fe(VI) synthesis are summarized. Direct electrochemical synthesis of Fe(VI) compounds has several advantages of shorter synthesis time, simplicity, reduced costs (no chemical oxidant is required) and providing a possible pathway towards more electro-active and thermal stable Fe(VI) compounds. Fe(VI) analytical methodologies summarized in this paper are a range of electrochemical techniques. Fe(VI) compounds have been explored as energy storage cathode materials in both aqueous and non-aqueous phase in “super-iron” battery configurations. In this paper, electrochemical synthesis of reversible Fe(VI/III) thin film towards a rechargeable super-iron cathode is also summarized.     

INTERFACIAL ADSORPTION OF 2-HYDROXY-5-NONYLBENZOPHENONE OXIME IN STATIC AND VIGOROUSLY STIRRED DISTRIBUTION SYSTEMS

ABSTRACT

The interfacial adsorption of 2-hydroxy-5-nonylbenzo-phenone oxime (LIX65N) at a n-heptane/water interphase was examined under static and vigorously stirred conditions, varying the aqueous pH from 2 to 12. In static systems, the pH and the concentration dependences of the interfacial tension were analysed on the basis of the Gibbs equation. The acid dissociation equilibrium at the interface was evaluated. In vigorously stirred systems, the interfacial adsorption was observed as a reversible, reproducible decrease of the organic phase concentration in response to stirring. A Langmuir isotherm was applicable for the adsorption of neutral LIX65N in acidic condition. The greater adsorption of the anionic form of LIX65N occurring in alkaline condition required an alternative isotherm.     

Non‐catalytic anhydride curing of hydrogenated bisphenol‐A glycidyl ether with 1,2,4‐cyclohexanetricarboxylic anhydride and light emitting diode encapsulation

Noncatalytic anhydride curing of hydrogenated bisphenol‐A glycidyl ether (YX8000) using hydrogenated trimellic anhydride (1,2,4‐cyclohexanetricarboxylic anhydride, H‐TMAn) and methylhexahydrophthalic anhydride (MeHHPA) were studied. Differential scanning calorimetry data shows no exthothermal under 190°C using MeHHPA without catalyst because of the low reactivity. On the other hand, H‐TMAn had higher reactivity and it can be cured without catalyst. The effect of anhydride concentration both on curing and on properties was studied in detail. For example, the highest T_g was found when YX8000 : H‐TMAn = 100 : 75 or YX8000 : MeHHPA = 100 : 100. The highest curing exothermal was found at similar ratio. Following, the encapsulation of light emitting diode (LED) was prepared with two anhydrides. Surface volume decrease was observed with MeHHPA by its evaporation, but H‐TMAn gave flat surface. After thermal cycle test of these LED, H‐TMAn was found to have better crack resistance than MeHHPA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 962–966, 2006     

Silica gel‐based adsorbents prepared via homogeneous and heterogeneous routes: adsorption properties and recycling as heterogeneous catalysts

Silica gel‐based adsorbents were prepared via homogeneous and heterogeneous routes using two silane coupling reagents, 3‐glycidoxypropyltrimethoxysilane and γ ‐chloropropyltrimethoxysilane. Characterization results showed that amino contents of the adsorbents prepared via the homogeneous route were higher than those of the adsorbents prepared via the heterogeneous route for both silane coupling reagents. The adsorption capabilities of the resulting four types of adsorbents for Hg(II), Cu(II), Au(III), Ni(II), Pb(II) and Ag(I) ions were compared. Good adsorption capability for Au(III) was observed for the new adsorbents and the maximum static saturated adsorption capacities for Au(III) could reach 0.67 mmol g^?1. Due to the formation of Au(0) particles in the adsorption process, which hampered the reusability of the spent adsorbents, alternative recycling of the spent adsorbents after Au(III) adsorption was sought. The spent adsorbents were treated with NaBH₄ and used as catalysts in the reduction of 4‐nitrophenol to 4‐aminophenol. After three catalytic cycles at 298 K, the k values indicated minimal decrease of catalytic activity. © 2017 Society of Chemical Industry     

Preparation and characterization of new photoactive polyamides containing 4‐(4‐dimethylaminophenyl)urazole units

4‐(4‐dimethylaminophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( DAPTD ) was prepared from 4‐dimethylaminobenzoic acid in five steps. The compound DAPTD was reacted with excess acetyl chloride in N,N‐dimethylacetamide (DMAc) solution and gave 1,2‐bisacetyl‐4‐[4‐(dimethylaminophenyl)]‐1,2,4‐triazolidine‐3,5‐dione as a model compound. Solution polycondensation reactions of monomer with succinyl chloride (SucC), suberoyl chloride (SubC), and sebacoyl chloride (SebC) were performed under conventional solution polymerization techniques in the presence of triethylamine and pyridine as a catalyst in N‐methylpyrrolidone (NMP) and led to the formation of novel aliphatic polyamides. These novel polyamides have inherent viscosities in the range of 0.09–0.21 dL/g in N,N‐dimethylformamide (DMF) at 25°C. Fluorimetric studies of the model compound as well as polymers were performed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 947–954, 2007     

Polymerization of 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( 1 ) was reacted with 1,8‐naphthalic anhydride ( 2 ) in a mixture of acetic acid and pyridine (3 : 2) under refluxing temperature and gave 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( NIPTD ) ( 3 ) in high yield and purity. The compound NIPTD was reacted with excess n‐propylisocyanate in N,N‐dimethylacetamide solution and gave 1‐(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐triazolidine‐3,5‐dione ( 4 ) and 1,2‐bis(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐ triazolidine‐3,5‐dione ( 5 ) as model compounds. Solution polycondensation reactions of monomer 3 with hexamethylene diisocyanate ( HMDI ), isophorone diisocyanate ( IPDI ), and tolylene‐2,4‐diisocyanate ( TDI ) were performed under microwave irradiation and conventional solution polymerization techniques in different solvents and in the presence of different catalysts, which led to the formation of novel aliphatic‐aromatic polyureas. The polycondensation proceeded rapidly, compared with conventional solution polycondensation, and was almost completed within 8 min. These novel polyureas have inherent viscosities in a range of 0.06–0.20 dL g^?1 in conc. H₂SO₄ or DMF at 25°C. Some structural characterization and physical properties of these novel polymers are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2861–2869, 2003     

Preparation and characterization of photocured thiol‐ene hydrogel: Adsorption of Au(III) ions from aqueous solutions

In this study, photocured a novel thiol‐ene hydrogels based on P(Penta3MP4/PEG‐DA/HEMA) were investigated for adsorption of Au(III) ions from aqueous solutions purposes. The photopolymerization kinetics of thiol‐ene‐based formulations was investigated by real‐time infrared spectroscopy. The chemical composition and surface morphology of hydrogels were also characterized. The effect of different parameters on Au(III) adsorption efficiency was examined in detail. Better adsorption behavior was achieved for Au(III) by P(Penta3MP4/PEG‐DA/HEMA) F1 hydrogels. The maximum uptake for Au(III) was at pH 0.5. Both Langmuir and Freundlich adsorption isotherm models were applied and the reusability of thiol‐ene hydrogels investigated. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Cloud Point Extraction and Separation of Scandium and Yttrium (III) with Triton X‐114 in the Presence or Absence 8‐Hydroquiloline as an Added Chelate

Abstract

In this paper, the cloud point extraction and separation of scandium and yttrium (III) via use of Triton X‐114 with and without 8‐hydroquiloline (HQ) as an added chelate agent are investigated. The effects of various parameters, such as the aqueous phase pH, HQ concentration, Triton X‐114 concentration, heating temperature, and incubation time, on the cloud point extraction of scandium and yttrium (III) are studied. The results demonstrate that, there are different extraction and separation behaviors for scandium and yttrium (III) with and without HQ as an added chelate. And in contrast to solvent extraction, cloud point extraction is an excellent method to extract and separate scandium and yttrium (III).     

Efficient Synthesis of Novel Bis(dipyrromethanes) with Versatile Linkers via Indium(III) Chloride‐Catalyzed Condensation of Pyrrole and Dialdehydes

A new efficient and mild protocol for synthesizing a series of novel bis(dipyrromethanes) with versatile arylene linkers through an indi‐ um(III) chloride‐catalyzed condensation reaction between various dialdehydes and pyrrole has been developed. This protocol is applicable to constructing a variety of bis(dipyrromethanes) with diverse functional linkers, which provides a powerful route to construct libraries of functionalized porphyrin dimers and even multiporphyrin arrays.     

Complexation Behavior of Iron(III) with Aloxime 800, D2EHPA,CYANEX 272, CYANEX 302, and CYANEX 301

Abstract

The extraction of iron(III) has been studied from chloride solutions with di(2‐ethylhexyl)phosphoric acid (D₂EHPA), bis(2,4,4‐trimethylpentyl)phosphinic acid (CYANEX 272) and its sulfur‐substituted analogs, called CYANEX 302, and CYANEX 301, and 5‐dodecylsalicylaldoxime (Aloxime 800).

Job's method was applied for the characterization of the iron(III) complexes dissolved in hexane. In the case of D₂EHPA and CYANEX 272, a 1:1 ligand‐to‐metal ratio was observed, thus inferring the coordination of additional compounds. No chloride transport occurred during extraction, therefore suggesting the formation of [Fe(OH)₂L] complexes. With CYANEX 302, a ratio of 2:1 was obtained, whereas for CYANEX 301, the results of Job's method indicated the presence of four extractant molecules around the metal ion. Less hydrolysis or the possible oxidation of the sulfur‐substituted organophosphinic acids and the corresponding reduction of Fe(III) towards Fe(II) may explain this behavior. In the case of Aloxime 800, the formation of the [FeL₃] species is suggested.

A comparative study was carried out to identify the ligand‐to‐metal ratio of the iron(III) complexes in anhydrous circumstances. These studies showed that 1:1 ligand‐metal complexes are easily formed in the case of the organophosphoric‐ and organophosphinic‐acid extractants. A higher ligand‐metal ratio may be possible, but is not always a necessary condition for iron(III) extraction. Even the coexistence of [FeCl₂L], [FeClL₂] and to a smaller extent [FeL₃] is quite presumable in anhydrous media. Finally, FT‐IR spectra as well as UV‐VIS spectra of the hexane phases make it possible to gain a better insight into the complexation characteristics of iron(III).     

Synergistic extraction of rare earths(III) from chloride medium with mixtures of 1‐phenyl‐3‐methyl‐4‐benzoyl‐pyrazalone‐5 and di‐(2‐ethylhexyl)‐2‐ethylhexylphosphonate

The synergistic effect of 1‐phenyl‐3‐methyl‐4‐benzoyl‐pyrazalone‐5 (HPMBP, HA) and di‐(2‐ethylhexyl)‐2‐ethylhexylphosphonate (DEHEHP, B) in the extraction of rare earths (RE) from chloride solutions has been investigated. Under the experimental conditions used, there was no detectable extraction when DEHEHP was used as a single extractant while the amount of RE(III) extracted by HPMBP alone was also low. But mixtures of the two extractants at a certain ratio had very high extractability for all the RE(III). For example, the synergistic enhancement coefficient was calculated to be 9.35 for Y³⁺, and taking Yb³⁺ and Y³⁺ as examples, RE³⁺ is extracted as RE(OH)A₂.B. The stoichiometry, extraction constants and thermodynamic functions such as Gibbs free energy change ΔG (?17.06 kJ mol^?1), enthalpy change ΔH (?35.08 kJ mol^?1) and entropy change ΔS (?60.47 J K^?1 mol^?1) for Y³⁺ at 298 K were determined. The separation factors (SF) for adjacent pairs of rare earths were calculated. Studies show that the binary extraction system not only enhances the extraction efficiency of RE(III) but also improves the selectivity, especially between La(III) and the other rare earth elements. Copyright © 2006 Society of Chemical Industry