A bipolar electrospray source of singly charged salt clusters of precisely controlled composition

The few clusters [B^?_nA⁺_n+1]⁺ (n = 0,1) with resolvable mobilities formed in electrosprays of large salts have been used for nanoparticle instrument testing and calibration at sizes smaller than 2 nm. Extensions of this modest size range by charge reduction with uncontrolled gas phase ions has resulted in impure singly charged clusters. Here, we combine two oppositely charged electrosprays of solutions of the same salt B^?A⁺, including: (C_nH_2n+1)₄N⁺Br^? (n = 4,7,12,16), the large phosphonium cation (C₆H₁₃)₃(C₁₆H₃₃)P⁺ paired with the anions Im^? [(CF₃SO₂)₂N^?] or FAP^? [(C₂F₅)₃PF₃^?], and the asymmetric pair [1-methyl-3-pentylimidazolium⁺FAP^?]. Both polarities are simultaneously produced by this source in comparable abundances, primarily as singly charged A⁺_nB^?_n±1, with tiny contributions from higher charge states. Some but not all of these clusters produce narrow mobility peaks typical of pure ions, even beyond n = 43. Excellent independent stable control of the positive and the negative sprays brought very close to each other is achieved by isolating them electrostatically with a symmetrically interposed metallic screen. Two nanoDMAs covering the size range up to 30 nm (Halfmini and Herrmann DMAs, with classification lengths of 2 and 10 cm) are characterized with these standards, revealing resolving powers considerably higher than previously seen with unipolar electrospray sources. The bipolar source of pure and chemically homogeneous clusters described permits studying size and charge effects in a variety of aerosol instruments in the 1–4 nm size range.

Copyright © 2017 American Association for Aerosol Research     

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.     

Effect of Coordination Modes of HL Ligand on the Molecular Architecture of Its Transition Metal Complexes (HL = 5-Methyl-2-Phenyl-4-[(2-<Emphasis Type="Italic">o</Emphasis>-Tolylamino)-Phenylmethylene]pyrazol-3(2H)-one)

Abstract  Two Ag⁺ complexes [Ag(HL)₂(PF₆)] (1) and [(AgL) _n  · n(CH₂Cl₂) · n(0.5H₂O)] (2) (HL = 5-methyl-2-phenyl-4-[(2-o-tolylamino)-phenylmethylene]pyrazol-3(2H)-one) were synthesized and structurally characterized by EA analysis, IR spectra and X-ray crystallography. The result shows that two expected coordination modes (Modes I and III in Scheme 1) of the HL ligand, can be observed in its Ag⁺ complexes, while not in other transition metal ions (Ni²⁺, Co²⁺ or Cu²⁺) complexes whether deprotonation or not for the HL ligand. Graphical Abstract  Three possible coordination modes (Modes I, II or III in Scheme 1) of the selected HL (HL = 5-methyl-2-phenyl-4-[(2-o-tolylamino)-phenylmethylene]pyrazol-3(2H)-one) ligand, can be adopted, in which Modes I and III can be observed in its two Ag⁺ complexes [Ag(HL)₂(PF₆)](1) and [(AgL) _n  · n(CH₂Cl₂) · n(0.5H₂O)] (2), while Mode II just observed in its transition metal ions (Cu²⁺, Ni²⁺, or Co²⁺) complexes, resulting from the deprotonatd form of the HL ligand and the coordination characters of transition metal ions.      

Extraction of Uranium and Thorium from Nitric Acid Solution by TODGA in Ionic Liquids

Extraction of uranium (UO₂²⁺) and thorium (Th⁴⁺) from a nitric acid solution into an imidazolium-type ionic liquids (ILs) of 1-alkyl-3-methylimidazolium hexafluorophosphate ([C_nmim][PF₆], n = 6 or 8) was carried out using N,N,N′,N′-tetraoctyl-3-oxapentanediamide (TODGA) as an extractant. It was found that the extraction efficiencies of UO₂²⁺ and Th⁴⁺ ions are higher in comparison with that done in n-dodecane. The extraction mechanism was deduced by the slope analysis and extraction experiment. Transfer of both ions is assumed to proceed predominantly through the neutral solvation mechanism from nitric acid solution into ILs. The UO₂²⁺ ion forms a 1:2 complex with TODGA in ILs at lower acidity, and a 1:1 complex in ILs and in n-dodecane at higher acidity. The Th⁴⁺ ion forms a 1:2 complex with TODGA in C₆mimPF₆ IL or a 1:1 complex in C₈mimPF₆ IL at lower acidity and a 1:1 complex in both ILs, and n-dodecane at higher acidity. Stripping studies were conducted using sodium salt of EDTA as a stripping ligand. The thermodynamics of extracting UO₂²⁺ ions and Th⁴⁺ ions from a 3 M HNO₃ solution was also studied. The results indicated that the extraction reactions are spontaneous and go through an exothermic process.     

Ionic liquid-based extraction and separation trends of bioactive compounds from plant biomass

Ionic liquids have been projected as the best solvent for extraction and separation of bioactive compounds from various origins. This review offers a collection of the published results, using ionic liquids for the extraction and purification of biomolecules. Ionic liquids have been studied as solvents, co-solvents and supported materials for separation of bioactive compounds. The ionic liquids-based extraction procedures were previously reported, such as ionic liquids-based solid-liquid extraction, liquid-liquid extraction and ionic liquids-modified materials are reviewed and compared to their performance. In this review, the main activities and future challenges are discussed, with major gaps identified using ionic liquids in extraction procedures and by advancing few steps to overcome these drawbacks.

Abbreviation: [(HSO₃)C₄MIM]⁺: 1-(4-sulfonylbutyl)-3-methylimidazolium; [(C₆H₃OCH₂)₂im]⁺: 1,3-dihexyloxymethylimidazolium; [C_nC₁MIM]⁺: 1-alkyl-2,3-dimethylimidazolium; [C_nMIM]^{+; [Cn, 2, 3, 4, 6, 8, 10, 12]}: 1-alkyl-3-methylimidazolium; [C_nC₁pyr]⁺: 1-alkyl-3-methylpyridinium; [C_nim]⁺: 1-alkylimidazolium; [C_npyr]⁺: 1-alkylpyridinium; [aC_nim]⁺: 1-allyl-3-alkylimidazolium; [C₇H₇MIM]⁺: 1-benzyl-3-methylimidazolium; [C₄(C₁C₁C₁Si)im]⁺: 1-butyl-3-trimethylsilylimidazolium; [(HOOC)C₂MIM]⁺: 1-carboxyethyl-3-methylimidazolium; [(OH)C_nMIM]⁺: 1-hydroxyalkyl-3-methylimidazolium; [(C₂H₅O)₃SiC₃MIM]⁺: 1-methyl-3-(triethoxy)silypropyl imidazolium; [(NH₂)C₃MIM]⁺: 1-propylamine-3-methylimidazolium; [C_wH_xN_yO_z]⁺: Chirally functionalized methylimidazolium; [P_{10(3OH)(3OH)(3OH)}]⁺: Decyltris(3-hydrox- ypropyl) phosphonium; [N_111(2OH)]⁺: N,N,N-trimethyl-N-(2-hydroxyethyl) ammonium (cholinium); [N_00nn]⁺: N,N-dialkylammonium; [N_0nn(2OH)]⁺: N,N-dialkyl-N-(2-hydroxyethyl) ammonium; [C₁₀C₁₀C₁gluc]⁺: N,N-didecyl-N-methyl-d-glucaminium; [N_11(2(O)1)0]⁺: N,N-dimethyl(2-methoxyethyl) ammonium; [N_{11(2OH)(C7H7)}]⁺: N-benzyl-N,N-dimethyl-N-(2-hydroxyethyl) ammonium; [P₆₆₆₁₄]⁺: Trihexyltetradecylph- osphonium; [P_i(444)1]⁺: Triisobutyl (methyl) phosphonium; P.minus: Polygonum minus; NPs: Nanoparticle; ZnO : Zinc oxide nanoparticles ; Ni NPs: Nickel nanoparticles; MO: Methyl orange; UAE: Ultrasonic-assisted extraction; LLE: Liquid-liquid extraction; ABS: Aqueous biphasic system ; [Ace]^?: Acesulfamate; [Ala]^?: alalinate; [TMPP]^?: bis(2,4,4-trimethylpentyl)phosphinate; : ; [NTf₂]^?: bis(trifluoromethylsulfonyl)imide; [[Br]^–]: [Br]omide; [Calc]: calkanoate; [Cl]^–: chloride; [Bz]^?: benzoate; [PF₆]^?: hexafluorophosphate; [HSO₄]^?: hydrogenosulfate; [OH]^?: hydroxide; I^–: iodide; [Lac]^?: lactate; [NO₃]^?: nitrate; [[Cl]O₄]^?: perchlorate; [Phe]^?: phenilalaninate; [BF₄]^?: tetrafluoroborate; [SCN]^?: thiocyanate; [C(CN)₃]^?: tricyanomethanide; [CF₃CO₂]^?: trifluoroacetate; [CF₃SO₃]^?: trifluoromethanesulfonate; [FAP]^?: tris(pentafluoroethyl)trifluorophosphate; ILs: Ionic liquids; Ag NPs: Silver nanoparticle; Cu NPs: Copper nanoparticle; MB: Methylene blue; MR: Methyl red ; MAE: Microwave-assisted extraction; SLE: solid-liquid extraction.     

Effect of phase modifiers TBP and iso-decanol on the extraction and complexation of Eu3+ with CMPO

The effect of tri-n-butyl phosphate (TBP) and iso-decanol as phase modifiers on the complexation of Eu³⁺ with octyl-phenyl N,N-diisobutyl carbamoyl methyl phosphine oxide (CMPO) was studied. On an increase of iso-decanol the extraction efficiency of Eu³⁺ decreases. The metal–ligand stoichiometry was found to be 1:3. The Eu complex of CMPO–TBP was more symmetric compared to CMPO–iso-decanol. The Eu³⁺ complex exhibited D_3h and C_3h symmetry for 30% and 5% iso-decanol, while that for TBP was C_6v. The radiative, non-radiative life time, electric and magnetic dipole transition probabilities, branching ratio, quantum efficiency etc. were evaluated. The covalency between Eu³⁺ and CMPO is as follows: CMPO–TBP < CMPO-5% iso-decanol < CMPO-30% iso-decanol.     

Extraction behaviour of dioxouranium(VI) cation by two phosphorous-based liquid cation-exchangers in room-temperature ionic liquids

Extraction of uranium with bis-(2-ethylhexyl) phosphonic acid (PC-88A) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex-272) was studied in several imidazolium-based room-temperature ionic liquids (RTILs), C_nmim·X (where n = 4, 6, 8 and X = PF₆ and Tf₂N). The extraction kinetics was slow and about 0.5–1 h equilibration time was required for most of the extraction systems, except in C₈mim·PF₆, where 2 h and 4 h were required to reach the equilibrium values for PC-88A and Cyanex-272, respectively. The extraction of UO₂²⁺ ion by the two ligands was significantly affected by the nature and the composition of the RTILs.     

2D Cationic Metal-Organic Frameworks of Ag+ with Mixed Ligands (Semi-Rigid Dipyridyl, 3-pmpmd, and Diphosphine, dppe)

Abstract  

With the complex 1 or 2 ([Ag(3-pmpmd)]_n·n(X) (X⁻ = BF₄ ⁻, 1; X = PF₆ ⁻, 2) from the semi-rigid 3-pmpmd (N,N′-bis(3-pyridylmethyl)-pyromellitic diimide) ligand and AgBF₄ or AgPF₆ as the precursor, two new coordination polymers [Ag₂(3-pmpmd)₂(dppe)(BF₄)₂]_n·4nDMF (3) and [Ag₂(3-pmpmd)₂(dppe)(PF₆)₂]_n·4nDMF (4) with the 2D cationic MOFs (metal-organic frameworks), have been obtained in the presence of the second dppe (Ph₂P(CH₂)₂PPh₂) ligand. In the 2D layer network, the 3-pmpmd ligands show the Z _T -mode and the Z _C -mode conformations, and the bridged dppe ligands have the same anti conformation. In the meantime, the functions of the two selected ligands, together with the supramolecular interactions from counter ions and solvates molecules within, should play a key role in the construction of the 2D noninterpenetrated network.     

Excitation-dependent energy transfer and color tunability in Dy3+/Eu3+ co-doped multi-component borophosphate glasses

Using the melt-quench technique, potassium zinc borophosphate (KZnBP) glasses incorporated with Dy³⁺, Eu³⁺, and Dy³⁺/Eu³⁺ ions individually and combinedly were prepared, and their photoluminescence (PL)-related features were investigated. The KZnBP glass containing an optimized content of Dy³⁺ (0.5 mol%) is co-doped with Eu³⁺ in various contents, and the energy transfer (ET) process between them was studied at λ_exci = 349, 364, 387 (Dy³⁺), and 394 nm (Eu³⁺). The Dy³⁺/Eu³⁺ co-doped system, when excited with Dy³⁺ excitations has resulted in a significant decrease in the intensity of Dy³⁺ peaks observed at 480 nm (⁴F_9/2→⁶H_15/2, blue) and 574 nm (⁴F_9/2→⁶H_13/2, yellow), with simultaneous enhancement of the intensity of Eu³⁺ peaks at 591 nm (⁵D₀→⁷F₁, orange) and 617 nm (⁵D₀→⁷F₂, red). This trend is due to the efficient energy transfer from Dy³⁺ to Eu³⁺, indicating that Eu³⁺ ions were sensitized by Dy³⁺ ions. Dexter's theory and the Inokuti–Hirayama (I–H) model revealed that the dipole–dipole interaction is accountable for the energy transfer from Dy³⁺ to Eu³⁺ through energy-transfer channels [⁴F_9/2(Dy³⁺)+⁷F_1,2(Eu³⁺)→⁶H_15/2(Dy³⁺)+⁵D₂(Eu³⁺)] and [⁴F_9/2(Dy³⁺)+⁷F₀(Eu³⁺)→⁶H_13/2(Dy³⁺)+⁵D₀(Eu³⁺)]. The color coordinates of the Dy³⁺/Eu³⁺ co-doped glasses under various excitations fall within the white light emission spectrum, indicating their potential application in warm white LEDs.     

Tandem DMA Generation of Strictly Monomobile 1–3.5 nm Particle Standards

Generation of monomobile molecular standards by electrospray (ES) followed by classification in a differential mobility analyzer (DMA) fails at diameters above ～2 nm because many clusters in different charge states z crowd in a narrow mobility range. Use of a second DMA (DMA₂) in series (tandem) with DMA₁ is very helpful because, unexpectedly, many multiply charged ions selected in DMA₁ undergo spontaneous transitions, appearing as pure species at different mobilities in DMA₂. Remarkably, for salt clusters of composition (CA) _n (C⁺ ) _z carrying z elementary charges and n neutral ion pairs, (i) ion evaporation (CA) _n (C⁺ ) _z →(CA) _{n –1}(C⁺ ) _{z– 1}+(CA)C⁺ and (ii) neutral evaporation transitions (CA) _n (C⁺ ) _z →(CA) _{n –1}(C⁺ ) _z+CA affect a substantial fraction of the clusters. Neutral evaporation (fueled by the Kelvin effect) is effective in isolating singly charged clusters, yielding mobility standards easily exceeding 2 nm. Ion evaporation (fueled by large electric fields) produces even larger well-resolved standards. Singly charged clusters of up to 2.5 nm rising in isolation result from metastable doubly charged parent ions (z = 2→1 transition). Isolated doubly charged ions of up to 3.5 nm arise from the z = 3→2 transition, but are harder to resolve from the products of higher initial charge states. We report tandem DMA measurements for electrosprayed nanodrops of two ionic liquids: EMI-Im and EMI-Methide, both based on the small cation EMI⁺ (1-Ethyl-3-methylimidazolium⁺) and two relatively large anions: Im^? = (CF₃SO₂)₂N^?; Methide^? = (CF₃SO₂)₃C^?. Some exploration on the effect of actively reducing the charge on the clusters as they pass between both analyzers is also included.

Copyright 2013 American Association for Aerosol Research     

Recovery of Furfural from Aqueous Solution by Ionic Liquid Based Liquid–Liquid Extraction

Abstract

Liquid–liquid extraction with imidazolium based ionic liquids ([C₄mim][PF₆], [C₆mim][PF₆], and [C₈mim][PF₆]) is proposed for the separation of furfural or 5-methylfurfural from aqueous solution. Factors affecting the extraction of furfural or 5-methylfurfural have been studied. It was shown that the extraction equilibria can be achieved within 30 min and the process was less affected by the factors such as volume ratio and feed concentration. The partition coefficients of furfural and 5-methylfurfural decreased with increasing temperature. [C₆mim][PF₆] was found to have the best extraction ability among the three ionic liquids studied. Presence of small amount of NaCl or Na₂SO₄ in the aqueous phase results in the considerable increase in the partition coefficients of furfural because of the competitive hydration of the salts with furfural. A thermodynamic study revealed that the extraction process was driven mainly by hydrophobic interactions. Further experimental results indicated that furfural can be separated selectively from aqueous furfural/acetic acid mixtures.     

Glycolamide-functionalized ionic liquid: Synthesis and actinide ion extraction studies

A glycolamide-functionalized ionic liquid (G-FIL) was synthesized for the first time and was evaluated for the extraction of actinide ions such as Am³⁺, Pu⁴⁺ and UO₂²⁺ and fission product element ions such as Eu³⁺, Sr²⁺ and Cs⁺. The extraction of the trivalent metal ions was found to be exceptionally high at low acid concentrations, which rapidly decreased with increasing acidity. In view of the high viscosity of the G-FIL, the studies were carried out using its diluted solution in a commercial ionic liquid, viz. 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C₄mim][Tf₂N]).     

Extraction relationship of Li+ and H+ using tributyl phosphate in the presence of Fe(III)

ABSTRACT

During the extraction of lithium from high Mg-containing salt lake brines by tributyl phosphate (TBP) in the presence of Fe(III), H⁺ is used to stabilize Fe(III). However, the distribution ratio of H⁺ (D_H) is 4–6 times higher than that of Li⁺ (D_Li), which affects the extraction of Li⁺ significantly. In this study, the competition mechanism between H⁺ and Li⁺ was investigated by spectral analysis and thermodynamic equilibrium. The extracted species are determined as HFeCl₄ · 2TBP and LiFeCl₄ · 2TBP for H⁺ and Li⁺, respectively. The apparent equilibrium constants are K_H = 799.8 and K_Li = 120.6, respectively. Both equilibrium constants and the distribution ratios for H⁺ and Li⁺ extraction show that extraction of H⁺ is stronger than Li⁺.     

Synthesis and photoluminescence enhancement of Ca3Sr3(VO4)4:Eu3+ red phosphors by co-doping with La3+

In this study, a series of red-emitting Ca₃Sr₃(VO₄)₄:Eu³⁺ phosphors co-doped with La³⁺ was prepared using the combustion method. The microstructures, morphologies, and photoluminescence properties of the phosphors were investigated. All Ca₃Sr₃(VO₄)₄:Eu³⁺, La³⁺ samples synthesized at temperatures greater than 700 ℃ exhibited the same standard rhombohedral structure of Ca₃Sr₃(VO₄)₄. Furthermore, the Ca₃Sr₃(VO₄)₄:Eu³⁺, La³⁺ phosphor was effectively excited by near-ultraviolet light of 393 nm and blue light of 464 nm. The strong excitation peak at 464 nm corresponded to the ⁷F₀→⁵D₂ electron transition of Eu³⁺. The strong emission peak observed at 619 nm corresponded to the ⁵D₀→⁷F₂ electron transition of Eu³⁺. Co-doping with La³⁺ significantly improved the emission intensity of Ca₃Sr₃(VO₄)₄:Eu³⁺ red phosphors. The optimum luminescence of the phosphor was observed at Eu³⁺ and La³⁺ concentrations of 5% and 6%, respectively. Moreover, co-doping with La³⁺ also improved the fluorescence lifetime and thermal stability of the Ca₃Sr₃(VO₄)₄:Eu³⁺ phosphor. The CIE chromaticity coordinate of Ca₃Sr₃(VO₄)₄:0.05Eu³⁺, 0.06La³⁺ was closer to the NTSC standard for red phosphors than those of other commercial phosphors; moreover, it had greater color purity than that of all the samples tested. The red emission intensity of Ca₃Sr₃(VO₄)₄:0.05Eu³⁺, 0.06La³⁺ at 619 nm was ~1.53 times that of Ca₃Sr₃(VO₄)₄:0.05Eu³⁺ and 2.63 times that of SrS:Eu²⁺. The introduction of charge compensators could further increase the emission intensity of Ca₃Sr₃(VO₄)₄:Eu³⁺, La³⁺ red phosphors. The phosphors synthesized herein are promising red-emitting phosphors for applications in white light-emitting diodes under irradiation by blue chips.     

Synthesis and characterization of Eu3+-doped C12H18Ca3O18 phosphor

A series of Eu³⁺-doped C₁₂H₁₈Ca₃O₁₈ phosphors were synthesized through a facile hydrothermal method and the properties of as-prepared phosphors were explored by X-ray diffractometer (XRD), scanning electron microscope (SEM), and photoluminescence (PL) spectrometer. The exploration results indicated that the C₁₂H₁₈Ca₃O_18:Eu³⁺ had been successfully synthesized. The morphology of C₁₂H₁₈Ca₃O_18:Eu³⁺ was a strip with the size of 100–4000 nm × 50–400 nm × 50–200 nm and the ratio of length to width of 2–80. The strongest emission peak of C₁₂H₁₈Ca₃O_18:Eu³⁺ around 620 nm was ascribed to ⁵D_o→⁷F₂ transition of Eu³⁺, and the peaks centered at 590, 653 and 694 nm respectively corresponded to ⁵D_o →⁷F₁, ⁷F₃, and ⁷F₄ transitions. C₁₂H₁₈Ca₃O_18: Eu³⁺ gave the red light emission, as indicated by color coordinate analysis. The photoluminescence intensity of the phosphors prepared under the Eu³⁺ concentration of 6% was the highest. The crystal structure of C₁₂H₁₈Ca₃O_18:Eu³⁺ was changed after europium ions occupied the lattice position of calcium ions. Europium ion could displace calcium arbitrarily. As a new kind of matrix, calcium citrate possesses the properties of both organic and inorganic compounds and the luminescent C₁₂H₁₈Ca₃O₁₈: x Eu³⁺ particles may be applied in biological fluorescent tags and luminescent materials.     

Structural-microstructural characterization and optical properties of Eu3+,Tb3+-codoped LaPO4·nH2O and LaPO4 nanorods hydrothermally synthesized with microwaves

Rhabdophane-type Eu³⁺,Tb³⁺-codoped LaPO₄·nH₂O single-crystal nanorods with the compositions La_0.99999-xEu_xTb_0.00001PO₄·nH₂O (x?=?0–0.03), La_0.99999-yTb_yEu_0.00001PO₄·n′H₂O (y?=?0–0.010), and La_0.99999-zTb_zEu_0.000007PO₄·n′′H₂O (z?=?0–0.012) were hydrothermally synthesized with microwaves. It is shown that the Eu³⁺,Tb³⁺ codoping does not affect the thermal stability of these nanorods, which is due to the formation of substitutional solid solutions with both Eu³⁺ and Tb³⁺ replacing La³⁺ in the crystal lattice. Moreover, it is also shown that monazite-type Eu³⁺,Tb³⁺-codoped LaPO₄ single-crystal nanorods can be obtained by calcining their rhabdophane-type Eu³⁺,Tb³⁺-codoped LaPO₄·(n,n′ or n′′)H₂O counterparts at moderate temperature in air, and that they are thermally stable. It is also observed that, for the same Eu³⁺,Tb³⁺-codoping content, the monazite-type Eu³⁺,Tb³⁺-codoped LaPO₄ nanorods exhibit higher photoluminescent efficiency than the rhabdophane-type Eu³⁺,Tb³⁺-codoped LaPO₄· (n,n′ or n′′)H₂O nanorods. Moreover, it is found that the highest photoluminescence emission corresponds to the monazite-type La_0.96999Eu_0.02Tb_0.00001PO₄ nanorods for the La_0.99999-xEu_xTb_0.00001PO₄ system. However, for those compositions energy transfer from Tb³⁺ to Eu³⁺ does not occur. In addition, for an efficient energy transfer to occur, a content of at least 1?mol% Tb³⁺ is needed in all the studied materials.     

Extraction of Uranyl Ion Using 2-Thenoyltrifluoro Acetone (HTTA) in Room Temperature Ionic Liquids

The extraction of UO₂²⁺ ion was studied using six different solvent systems containing 2-thenoyltrifluoroacetone (HTTA) in room temperature ionic liquids such as [C_nmim][X] (where, n = 4, 6, or 8 and X^? = PF₆^? or NTf₂^?) from low to moderate pH solutions for the first time. The extraction kinetics studies indicated rather slow attainment of equilibrium which in some cases improved if the solutions were pre-equilibrated with the aqueous phase prior to the actual experiments. The D_U values were found to increase with increasing pH and leading to a plateau like profile at higher pH values. The D values were quite high as compared to that obtained with molecular diluents. The nature of the extracted species was ascertained by slope analysis method which suggested species of the type: UO₂(TTA)⁺_IL, UO₂(TTA)_2,IL, and UO₂(TTA)₂(HTTA)_IL in different ionic liquid based solvents. Temperature variation studies on UO₂²⁺ ion extraction were also carried out and the thermodynamic parameters were calculated which indicated high endothermicity of the reactions with large positive entropy values.     

Lanthanides Extraction by 8-Quinolinol and by a Mixture of Quinolinol and Trioctylphosphine Oxide

ABSTRACT

The solvent extraction of Nd³⁺ , Sm³⁺, Eu³⁺ , Gd³⁺, Dy³⁺ , Ho³⁺ , and Er³⁺ from a M ionic strength medium (CH₃COONa), pH (CH₃COOH) by 8-quinolinol (HOx) and by a mixture of HOx and trioctylphosphine oxide (TOPO) in CCl₄, CHCl₃, C₆H₆, C₆H₅—NO₂, C₆H₅—CH₃ C₆H₅Cl and C₆H₅—Br is studied using titrimetric methods. A synergistic factor of over 10,000 is obtained. The atomic number and diluent effects are evident in the calculated formation constants and the lanthanide separation factors. A combination of the data obtained and that of Th⁴⁺ indicates that an excellent separation of thorium from the lanthanides can be obtained with this extraction system.     

Application of High-Speed Counter-Current Chromatography Preparative Separation of Flavone C-Glycosides From Lophatherum gracile

Preparative high-speed counter-current chromatography (HSCCC) was used to separate and purify bioactive constituents from the stems and leaves of Lophatherum gracile Brongn. Six flavone C-glycosides each at over 95% purity including two new compounds were obtained in one-step separation by HSCCC with an optimized two-phase solvent system composed of ethyl acetate-n-butanol-ethanol-water at volume ratio of 4:2:1.5:8.5 (v/v/v/v). The experiment yielded 19.9 mg of luteolin 6-C-β-D-galactopyranosiduronic acid (1→2)-β-D-glucopyranoside (1), 28.5 mg of luteolin 6-C-α-L-arabinopyranosyl-7-O-β-D-glucopyranoside (2), 31.5 mg of isoorientin (3), 44.8 mg of orientin (4), 25.3 mg of swertiajaponin (5) and 12.1 mg of apigenin 6-C-β-D-galactopyranosiduronic acid (1→2)-β-D-glucopyranoside (6) from 500 mg of crude extracts. The purity of these compounds was determined by high-performance liquid chromatography (HPLC). Their chemical structures were identified by electron spray ionization mass spectroscopy (ESI-MS), ¹H and ¹³C nuclear magnetic resonance spectroscopy (NMR).     

Kinetics of Solvent Extraction of Iron(III) from Sulfate Medium by Purified Cyanex 272 using a Lewis Cell

Abstract

The kinetics of the forward and backward extraction of the title process have been investigated using a Lewis cell operated at 3 Hz and flux or (F) – method of data treatment. The dependences of (F) in the forward extraction on [Fe³⁺], [H₂A₂]_(o), pH, and [HSO₄ ^?] are 1, 0.5, 1, and ?1, respectively. The value of the forward extraction rate constant (k _f ) has been estimated to be 10^?7.37 kmol^3/2 m^?7/2 s^?1. The analysis of the experimentally found flux equation gives the following simple equation: F _f =10^0.13 [FeHSO₄ ²⁺] [A^?], on considering the monomeric model of BTMPPA and the stability constants of Fe(III)‐HSO₄ ^? complexes. This indicates the following elementary reaction occurring in the aqueous film of the interface as rate determining: [FeHSO₄]²⁺+A^?→[FeHSO₄.A]⁺. The very high activation energy of 91 kJ mol^?1 supports this chemical reaction step as rate-determining. The negative value of the entropy change of activation (?94 J mol^?1 K^?1) indicates that the slow chemical reaction step occurs via the S_N2 mechanism.

The backward extraction rate can be expressed by the equation: F _b =10^?5.13 [[FeHSO₄A₂]]_(o) [H⁺] [H₂A₂]_(o) ^?0.5. An analysis of this equation leads to the following chemical reaction step as rate-determining: [FeHSO₄A₂]_(int)→[FeHSO₄A]+A_(i) ^?. However, the activation energy of 24 kJ mol^?1 suggests that the backward extraction process is intermediate controlled with greater contribution of the diffusion of one or the other species as a slow process. The equilibrium constant obtained from the rate study matches well with that obtained from the equilibrium study.