Toward greener separations of rare earths: Bifunctional ionic liquid extractants in biodiesel

Ionic liquids (ILs) containing quaternary phosphonium cations and phosphonic acid anions were explored as novel extractants for rare earths (RE) separation. They were considered to be bifunctional ionic liquid extractants (bif‐ILEs), since both cations and anions of ILs were involved in the extraction. Trihexyl(tetradecyl)phosphonium bis 2,4,4‐trimethylpentylphosphinate (Cyphos IL 104), as a bif‐ILE, together with propylene carbonate (PC), dimethyl carbonate (DMC), and soybean oil methyl ester (SBME, biodiesel) as diluents was employed in the extraction of RE(III) from aqueous solutions. Acidified Cyphos IL 104 (HNO₃‐Cyphos IL 104) exhibited high solubility in three diluents, and higher extraction efficiency than bis(2,4,4‐trimethylpentyl)phosphinic acid (Cyanex 272) because of the coextraction of RE(III) by quaternary phosphonium cation and phosphonic acid anion in organic phase. Additionally, this coextraction mechanism could eliminate the loss of IL. The physical properties and miscibility test results indicated that SBME was an excellent solvent for RE(III) extraction. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Deep oxidative–extractive desulfurization of fuels using benzyl‐based ionic liquid

Four benzyl‐based ionic liquids (ILs) were synthetized and used for deep desulfurization of model oil and real diesel fuel. The removal efficiencies of benzothiophene (BT) and dibenzothiophene (DBT) with [Bzmim][NTf₂] and [Bzmim][SCN] as extractants are higher than that with [Bzmp][NTf₂] and [Bzmp][SCN] as extractants. The desulfurization capability follows the Nernst's Law. A reactive extraction mathematical model for desulfurization was established. An oxidative‐extractive two‐step deep desulfurization method was developed. DBT was first oxidized by H₂O₂ with CH₃COOH as catalyst and then the unoxidized DBT and uncrystallized dibenzothiophene sulfoxide (DBTO₂) in model oil were extracted by [Bzmim][NTf₂], and finally the removal efficiency was 98.4% after one‐stage extraction. Besides, the removal efficiency of 4,6‐DMDBT was 96.4% after oxidation and one‐stage extraction processes. Moreover, the oxidative‐extractive two‐step deep desulfurization method was also effective for desulfurization of diesel fuel. The removal efficiency of sulfur reached up to 96% after oxidation and three‐stage cross‐current extraction processes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4023–4034, 2016     

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     

Studies on solvent extraction of La(III) using [A336][NO3–] and modeling by statistical analysis and neural network

Solvent extraction of La(III) from acidic nitrate medium has been studied with [A336][NO₃^–] in kerosene. The factors affecting the extraction of La(III) like equilibration time, nitrate ion, extractant and La(III) concentrations, aqueous acidity, O/A ratio variation, nature of diluent, and temperature have been investigated. McCabe-Thiele diagram has been plotted to find out the actual number of theoretical stages needed for complete extraction of lanthanum. The solvent has been successfully regenerated for further use after stripping of the metal. IR studies of [A336][NO₃^–] and La(III) loaded [A336][NO₃^–] have been carried out. Modeling of extraction data has been done using Multiple linear regression analysis and Artificial Neural Network, and the performances have been compared. Error in each case was evaluated in terms of R² and Root mean squared error (RMSE). Maximum extraction of La(III) was 82% when 0.6 M [A336][NO₃^–] was used for extraction. About 98% of the metal has been recovered using 0.2 M HNO₃ as stripping agent. Extractive separation of La(III) and Sm(III) was maximum (β = 65.2) using 0.1 M [A336][NO₃^–]. IR studies revealed formation of lanthanum complex in the extraction process. Artificial Neural Network proved to be better over Multiple linear regression in data prediction.     

Behavior of a synergistic system in the extraction of Pr(III) from chloride medium using di-2-ethylhexyl phosphoric acid and 2-ethylhexylphosphonic mono-2-ethylhexyl ester

This paper will investigate the synergistic solvent extraction of extracted Pr from a chloride medium, using a mixture of two acidic extractants, namely 2-ethylhexylphosphonic mono-2-ethylhexyl ester (P507, HA) and di-2-ethylhexyl phosphoric acid (P204, HB) in kerosene. The stoichiometry of the extracted species was characterized by a classical lg–lg plot analysis. The composition of the extracted complexes has been determined as Pr(HA₂)(HB₂)₂. Moreover, the differences of the extraction behavior from sulfuric and chloride medium were discussed in detail. The values of equilibrium constant and thermodynamic parameters such as △G, △H, and △S were also calculated. A cation-exchange mechanism was proposed and further clarified by slope analysis and IR spectra.     

Reactive extraction of itaconic acid using tri‐n‐butyl phosphate and aliquat 336 in sunflower oil as a non‐toxic diluent

Itaconic acid finds a place in various industrial applications. It can be produced by biocultivation in a clean and environment friendly route but recovery of the acid from the dilute stream of the bioreactor is an economic problem. Reactive extraction is a promising method to recover carboxylic acid but suffers from toxicity problems of the diluent and extractant employed. So there is need for a non‐toxic extractant and diluent or a combination of less toxic extractants in a non‐toxic diluent that can recover acid efficiently. Effect of different extractants: tri‐n‐butylphosphate (TBP) (an organophosporous compound) and Aliquat 336 (a quaternary amine) in sunflower oil was studied to find the best extractant–sunflower oil combination. Equilibrium complexation constant, K_E, values of 1.789 and 2.385 m³ kmol^?1, respectively, were obtained for itaconic acid extraction using TBP and Aliquat 336 in sunflower oil. The problem of toxicity in reactive extraction can be reduced by using a natural non‐toxic diluent (sunflower oil) with the extractant. Copyright © 2010 Society of Chemical Industry     

Comparison in the extraction behavior of uranium(VI) from nitric acid medium using CHON based extractants,monoamide, malonamide,and diglycolamide,dissolved in piperidinium ionic liquid

Liquid-liquid extraction of U(VI) from nitric acid medium was carried out using three different class of CHON based molecular extractants namely monoamide, malonamide, and diglycolamide present in 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide ([C₄mpip][NTf₂]) ionic liquid. The extractants investigated were di-n-hexyloctanamide (DHOA), N,N-dimethyl-N,N-di-octyl-2-(2-hexyloxylethyl)malonamide (DMDOHEMA) and N,N,N’,N’-tetra(ethylhexyl)diglycolamides (T2EHDGA). The extraction behavior of uranium(VI) in ionic liquid medium was investigated as a function of various parameters, such as the duration and temperature of equilibration, aqueous phase concentrations of feed acid, extractant, NaNO₃, and ionic liquid cation, etc. The extraction of U(VI) observed in these systems were compared with each other and the distribution ratios of U(VI) decreased in the order T2EHDGA > DMDOHEMA > DHOA. The slope analysis of the extraction data was carried out to understand the mechanistic aspects of extraction. The extraction of U(VI) observed in [C₄mpip][NTf₂] ionic liquid was also compared with pyrrolidinium ([C₄mpyr][NTf₂]) and imidazolium ([C₄mim][NTf₂]) based ionic liquids under identical experimental condition.     

Hydration counteracts the separation of lanthanides by solvent extraction

The extraction of lanthanides from aqueous nitrate solutions by quaternary ammonium nitrate ionic liquids (e.g., [A336][NO₃]) shows a negative sequence (i.e., light lanthanides are more efficiently extracted than heavy lanthanides), which conflicts with the lanthanide contraction. In this study, we explored the origin of the negative sequence by investigating the extraction of lanthanides from ethylammonium nitrate by [A336][NO₃]. The extraction shows a positive sequence, which is converted to a negative sequence with the addition of water. The transformation from positive to negative sequences reveals that the negative sequence is caused by the hydration of lanthanide ions: hydration of lanthanide ions counteracts the extraction. Therefore, the use of solvents that have weak solvation with lanthanide ions might enhance the separation of the elements by solvent extraction.     

Graphene oxide functionalized by poly(ionic liquid)s for carbon dioxide capture

Poly(ionic liquid)s have been demonstrated as high efficient CO₂ absorbents. In the current study, a kind of poly(ionic liquid)s, Poly[2‐(methacryloyloxy)‐ethyl] trimethylammonium tetrafluoroborate (P[MATMA][BF₄]) was used to functionalize graphene oxide (GO). The hybrid in which P[MATMA][BF₄] was covalently bonded on GO platelets was prepared by a simple method, that is, traditional radical polymerization. The characterizations based on transmission electron microscopy, scanning electron microscope, Fourier transform infrared spectroscopy, Raman spectroscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy demonstrated the graft of P[MATMA][BF₄] on GO. N₂ adsorption measurements indicated that P[MATMA][BF₄] also greatly increased the specific surface area of GO. Due to the higher specific surface area and the CO₂ affinity of P[MATMA][BF₄], the GO‐P[MATMA][BF₄] hybrid exhibited a much higher CO₂ adsorption capacity compared with GO, GO‐NH₂, and P[MATMA][BF₄]. Their study showed that the combinations of poly(ionic liquid)s and GO could be promising CO₂ absorbents. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44592.     

Effect of small amount of water on the dynamics properties and microstructures of ionic liquids

A series of systems of 1‐butyl‐3‐methylimidazolium acetate ([Bmim][Ac]), 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([Bmim][BF₄]), and 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][Tf₂N]) with a small amount of water were simulated. Viscosities of systems were obtained by nonequilibrium molecule dynamics simulation and the results show that the viscosities change in different ways: for [Bmim][BF₄] and [Bmim][Tf₂N], viscosities decrease rapidly in the first stage, and then decrease slowly with the increase of water content. But for [Bmim][Ac], the viscosities increase first and then decrease. The unique phenomenon of [Bmim][Ac] can be attributed to the formation of chain‐like structure of anion???water???anion???. Hydrogen bond (HB) interaction between ion pairs is weakened, but the number of HB between water and anions increases with increase of water content. Besides, the microstructures of water in ionic liquids‐water systems were compared and found that the distribution of water is more concentrated in [Bmim][Tf₂N]‐H₂O system, while it is isotropy in [Bmim][Ac]‐H₂O system. © 2016 American Institute of Chemical Engineers AIChE J, 63: 2248–2256, 2017     

有机磷(膦)酸萃取钴和镍的动力学行为比较

依据实验结果和文献数据讨论了有机磷酸类萃取剂萃取钴及镍的动力学行为.结果表明,有机磷酸酸性强,溶入水相的速度快,则萃取速度亦快,钴和镍的萃取速度差异由溶剂交换速度决定.     

Reactive extraction of propionic acid using tri‐n‐octylamine,tri‐n‐butyl phosphate and aliquat 336 in sunflower oil as diluent

BACKGROUND : Propionic acid is widely used in chemical and allied industries and can be produced by biocultivation in a clean and environmentally friendly route. Recovery of the acid from the dilute stream from the bioreactor is an economic problem. Reactive extraction is a promising method of recovering the acid but suffers from toxicity problems of the solvent employed. There is thus a need for a non‐toxic solvent or a combination of less toxic extractants in a non‐toxic diluent that can recover acid efficiently. RESULTS: The effect of different extractants (tri‐n‐butylphosphate (TBP), tri‐n‐octylamine (TOA) and Aliquat 336) and their mixed binary solutions in sunflower oil diluent was studied to find the best extractant‐sunflower oil combination. Equilibrium complexation constant, K_E, values of 4.02, 3.13 and 1.87 m³ kmol^?1 were obtained for propionic acid extraction using Aliquat 336, TOA and TBP, respectively, in sunflower oil. The effect of different modifiers (1‐decanol, methylisobutyl ketone, butyl acetate and dodecanol) on the extraction was also studied and it was found that modifiers enhance extraction, with 1‐decanol found to be the best. CONCLUSION: The problem of toxicity in reactive extraction can be reduced by using a non‐toxic diluent (sunflower oil) or a modifier in a non‐toxic solvent, with the extractant. The addition of modifiers was found to improve the extraction. Copyright © 2008 Society of Chemical Industry     

Synthesis of new crosslinked porous ammonium‐based poly(ionic liquid) and application in CO2 adsorption

A new poly(ionic liquid) of N,N‐methylenebisacrylamide (MBA)‐crosslinked‐poly(4‐vinylbenzyltriethylammonium hexafluorophosphate)(MBA‐crosslinked‐P[VBTEA][PF₆]) is prepared through the ion exchange of KPF₆ with the precursor of MBA‐crosslinked‐P[VBTEA][Cl]; the precursor is synthesized by 4‐vinylbenzyltriethylammonium chloride and MBA via inverse suspension polymerization. MBA‐crosslinked‐P[VBTEA][PF₆] is a thermally stable (decomposes at nearly 300°C) and porous (apparent porosity of 64.3% and specific surface of 39.12 m²/g) polymer particle with high purity, as indicated by Fourier transformed infrared, energy dispersive spectroscopy, thermogravimetric, scanning electron microscopy, and porous analyses. It is observed that MBA‐crosslinked‐P[VBTEA][PF₆] has good CO₂ adsorption capability of 14.04 mg/g at 0.2 MPa and 25°C, and can be recovered by desorption at vacuum and 80°C, and reused with 99% CO₂ adsorption after four cycles. POLYM. ENG. SCI., 54:59–63, 2014. © 2013 Society of Plastics Engineers     

The adjustable synergistic effects between acid–base coupling bifunctional ionic liquid extractants for rare earth separation

Two of the most widely used industrial extractants for rare earth elements (REEs), that is, di(2‐ethylhexyl)phosphoric acid (HDEHP) and 2‐ethyl(hexyl) phosphonic acid mono‐2‐ethylhexyl ester (HEH[EHP]) were developed into [DEHP]^? type acid–base coupling bifunctionalized ionic liquids (ABC‐BILs) and [EHEHP]^? type ABC‐BILs, respectively. The combinations of ABC‐BIL extractants revealed synergistic effects for REEs. Seven different combinations of ABC‐BILs and five kinds of REEs confirmed the novel synergistic extraction. Some synergy coefficients of the combined ABC‐BILs were bigger than those of mixed HDEHP and HEH[EHP] by two orders of magnitude. The first synergistic extraction produced by ionic liquid extractants in the field of solvent extraction was reported in this article. The novel synergistic extraction from combined ABC‐BILs extractants revealed highly efficient and environmentally friendly potential in both of academic research and industrial application for REEs separation. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3859–3868, 2014     

P507与N53在煤油体系中对酚类物质萃取效率的比较研究

选用P507(0-(2-乙基已基)-2-乙基已基磷酸酯)和N503(N,N二-(1-甲基庚基)乙酰胺)2种有机萃取剂对酚的质量浓度为4 500 mg/L的废水进行处理.在煤油体系中,考察了油水体积比、pH值、萃取体系相比、萃取温度、萃取时间等因素对P507和N503萃取剂效果的影响.试验结果表明,在pH值为3～3.5,...     

Extraction of Lanthanides(III), U(VI), and Th(IV) from Nitric Acid Solutions with 1,5-N,N'-Bis[(diphenylphosphoryl)acetylamino]pentanes

Novel polyfunctional neutral organophosphorus ligands, namely 1,5-N,N'-bis[(diphenylphosphoryl)acetyl(alkyl)amino]pentanes [Ph₂P(O)CH₂C(O)NR]₂(CH₂)₅ (Ia, R = C₆H₁₃; Ib, R = CH₃), were studied as extractants for Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, and U from nitric acid solutions. The effect of both HNO₃ concentration in the aqueous phase and that of the extractant in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes was determined by the slope analysis method. Compared with the related bisaminopentane [Ph2P(O)CH₂C(O)NH]₂(CH₂)₅ (Ic), the replacement of hydrogen atoms at the amide nitrogens by alkyl radicals (compounds Ia,b) leads to an increase of metal ions extraction. Bis-CMPO ligands Ia-c were found to possess higher extraction efficiency towards U(VI), Th(IV), and Ln(III) than their monophosphorylated analogue Ph₂P(O)CH₂C(O)N(C₄H₉)₂.     

Micellization behavior of ionic liquid surfactants with two hydrophobic tail chains in aqueous solution

The drop volume method was used to determine the surface tensions of two series of polymerizable ionic liquid surfactants, namely, 1‐acryloyloxypropyl‐3‐alkylimidazolium chloride [APC_nim][Cl] (n = 8, 10, 12) containing two hydrophobic tail chains and 1‐propionyloxypropyl‐3‐alkylimidazolium chloride [PPC_nim][Cl] (n = 8, 10, 12), which showed similar structures with [APC_nim][Cl] (n = 8, 10, 12) at 25°C. The surface properties of the surfactants were also compared. Furthermore, the thermodynamic behavior of [PPC_nim][Cl] (n = 10, 12, 14) micellization in aqueous solution and the enthalpy–entropy compensation phenomenon were studied. The two kinds of surfactants had high surface activity. Double bonds had almost no effect on the surface properties of [APC_nim][Cl]. The micellization of [PPC_nim][Cl] in aqueous solution was spontaneous and entropy‐driven. For the surfactant with specific structure, micellization ability initially increased and then decreased with temperature increase. The entropic contribution to Gibbs free energy change tended to decrease, whereas the enthalpic contribution increased. In addition, the enthalpy–entropy compensation phenomenon occurred during the micellization process. For all [PPC_nim][Cl], the compensation temperature was (314 ± 1) K, which remained unaffected by the surfactant molecular structure. However, when the hydrophobic carbon chain length increased, both micelle formation ability and stability increased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Studies on the Extraction of Actinides Using a Solvent Containing D2EHiBA in Room Temperature Ionic Liquids: Unusual Extraction of the Tetravalent Ions

The extraction behavior of U(VI), Pu(IV), and Np(IV) from nitric acid medium has been studied using branched chain di(2-ethylhexyl)isobutyramide (D2EHiBA) dissolved in different room temperature ionic liquids (RTILs) [C_nmim][NTf₂] (where n = 4, 6, or 8). Uranium extraction (D_U) increased gradually with aqueous phase acidity for the three RTILs used in this study suggesting solvation mechanism. There was a reversal in the extraction behavior of Pu(IV) and Np(IV) from nitric acid medium using D2EHiBA dissolved in RTILs as solvents as compared to the behavior reported in the molecular diluent, n-dodecane, which shows negligible extraction of these metal ions. The extraction of Pu(IV) increased with aqueous phase acidity in different RTILs in the order: [C₈mim][NTf₂] > [C₆mim][NTf₂] > [C₄mim][NTf₂]. The distribution ratio values of these metal ions followed the order: D_Pu(IV) ≥ D_Np(IV) > D_U(VI) using D2EHiBA as extractant suggesting that RTILs can modify the extraction behavior of extractants.     

Blue solid‐state luminescent tetraphenylethene–organophosphorus dyads with aggregation‐induced emission characteristics

Three novel tetraphenylethene–organophosphorus dyads – (6‐oxido‐6H‐dibenz[c,e][1,2]oxaphosphorin‐6‐yl)[4‐(1,2,2‐triphenylvinyl)phenyl] methanol, diphenyl {hydroxy[4‐(1,2,2‐triphenylvinyl)phenyl]methyl} phosphine oxide, and di(3,5‐dimethylphenyl){hydroxy[4‐(1,2,2‐triphenylvinyl)phenyl] methyl} phosphine oxide – were synthesised and characterised by ¹H, ¹³C, and ³¹P nuclear magnetic resonance spectroscopy, mass spectrometry, and elemental analysis. The photoluminescence properties were studied. All three dyads exhibited intense solid‐state blue emission peaking at 449–466 nm, and also displayed aggregation‐induced emission behaviours. The emission decays of these dyads in the solid state also fitted well with a triexponential model with an average lifetime of 2.65–4.42 ns. The experimental results demonstrated that the luminescent properties are highly dependent on the nature of the organophosphorus groups. The choice of phosphorus‐containing components can cause variations in the photoluminescence emission and photoluminescence decays.