Facile synthesis of calcium carbonate with an absolutely pure crystal form using 1-butyl-3-methylimidazolium dodecyl sulfate as the modifier

Calcium carbonate (CaCO₃) nanocrystals with controllable polymorph and morphology have been successfully synthesized with the aid of an effective control agent, a halogen-free, low-cost ionic liquid surfactant, 1-butyl-3-methylimidazolium dodecylsulfate ([C₄mim][C₁₂SO₄]) in a supersaturated aqueous solution. For the first time, facile preparation of pure lens-like vaterite, sheet-like calcite, and peanut-like aragonite was all achieved in the [C₄mim][C₁₂SO₄] aqueous solution through changing the concentration, temperature, and initial pH value and adding magnesium ions. Washed by water and ethanol, all the aggregates were free of [C₄mim][C₁₂SO₄] and can be stable at least 1 month in air. The crystal form of the aggregates changed from pure calcite to pure vaterite at room temperature only through increasing [C₄mim][C₁₂SO₄] concentration. Formation of the ordered CaCO₃ structures is mainly ascribed to the aggregation of the primary nanoparticles whose formation mechanism is related to the change of supersaturation. This study can provide a facile and environment-friendly method to fabricate CaCO₃ crystal aggregates with various morphologies and polymorphs and can be used for large-scale industrial production and biomimetic synthesis.     

Study of the behaviour of the azeotropic mixture ethanol–water with imidazolium-based ionic liquids

In this work, experimental data of isobaric vapour–liquid equilibria for the ternary system ethanol + water + 1-hexyl-3-methylimidazolium chloride ([C₆mim][Cl]) and for the corresponding binary systems containing the ionic liquid (ethanol + [C₆mim][Cl], water + [C₆mim][Cl]) were carried out at 101.300 kPa. VLE experimental data of binary and ternary systems were correlated using the NRTL equation. In a previous work [N. Calvar, B. González, E. Gómez, A. Domínguez, J. Chem. Eng. Data 51 (2006) 2178–2181], the VLE of the ternary system ethanol + water + [C₄mim][Cl] was determined and correlated, so we can study the influence of different ionic liquids in the behaviour of the azeotropic mixture ethanol–water.     

Ultrafast FRET to Study Spontaneous Micelle‐to‐Vesicle Transitions in an Aqueous Mixed Surface‐Active Ionic‐Liquid System

The spontaneous micelle‐to‐vesicle transition in an aqueous mixture of two surface‐active ionic liquids (SAILs), namely, 1‐butyl‐3‐methylimidazolium n‐octylsulfate ([C₄mim][C₈SO₄]) and 1‐dodecyl‐3‐methylimidazoium chloride ([C₁₂mim]Cl) is described. In addition to detailed structural characterization obtained by using dynamic light scattering, transmission electron microscopy (TEM), and cryogenic TEM techniques, ultrafast fluorescence resonance energy transfer (FRET) from coumarin 153 (C153) as a donor (D) to rhodamine 6G (R6G) as an acceptor (A) is also used to study micelle–vesicle transitions in the present system. Structural transitions of SAIL micelles ([C₄mim][C₈SO₄] or [C₁₂mim]Cl micelles) to mixed SAIL vesicles resulted in significantly increased D –A distances, and therefore, increased timescale of FRET. In [C₄mim][C₈SO₄] micelles, FRET between C153 and R6G occurs on an ultrafast timescale of 3.3 ps, which corresponds to a D –A distance of about 15 Å. As [C₄mim][C₈SO₄] micelles are transformed into mixed micelles upon the addition of a 0.25 molar fraction of [C₁₂mim]Cl, the timescale of FRET increases to 300 ps, which suggests an increase in the D –A distance to 31 Å. At a 0.5 molar fraction of [C₁₂mim]Cl, unilamellar vesicles are formed in which FRET occurs on multiple timescales of about 250 and 2100 ps, which correspond to D –A distances of 33 and 47 Å. Although in micelles and mixed micelles the obtained D –A distances are well correlated with their radius, in vesicles the obtained D –A distance is within the range of the bilayer thickness.     

水热条件下金红石纳米晶在离子液体[C12mim]Cl中的制备

在室温离子液体1-十二烷基-3-甲基氯化咪唑([C12mim]Cl)中,通过水热法制备了具有单晶结构的金红石纳米材料。采用X射线衍射、扫描电镜和透射电镜对样品进行了表征,结果显示所得样品为纯金红石相,形貌呈棒状。扫描电镜和透射电镜图样显示金红石纳米棒的直径约为15 nm,长度在10～100 nm之间。高分辨投射电镜图样显示金红石纳米棒为单晶结构,并沿c轴方向生长。实验结果表明离子液体[C12mim]Cl中的Cl-有利于金红石相生成,[C12mim]+起到了模板剂的作用并提高了金红石纳米棒的结晶度。     

Calorimetric Study on the Ion Pairing and Aggregation of 1-Ethyl-3-Methylimidazolium bis(trifluoromethylsulfonyl)amide ([C2mim][NTf2]) and Related Ionic Liquids in the Low-Dielectric Constant Solvent Chloroform

A calorimetric study of dissolution of the ionic liquids (ILs) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([C₂mim][NTf₂]), 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([C₆mim][NTf₂]), and 1-hexyl-3-methylimidazolium tris(trifluoromethylsulfonyl)methide ([C₆mim][CTf₃]) into chloroform (CHCl₃) is presented with particular focus on [C₂mim][NTf₂]. The interpretation of the calorimetric data for [C₂mim][NTf₂] was aided by additional NMR self-diffusion measurements and viscosity measurements that through the Stokes–Einstein equation provided information about the average size of the species present. It is evident that the main equilibrium species are ion pairs and aggregates. An estimate for the enthalpy contribution from aggregate formation for [C₂mim][NTf₂] was found to be ?2.09 kJ per mol of added IL at 288.2 K and slightly decreasing in magnitude to ?1.11 kJ·mol^?1 at 318.2 K. While all three ILs release heat upon dissolution into CHCl₃, different temperature trends are observed demonstrating the fine balance of competing contributions from breaking IL interactions, cavity formation for the solutes to reside in, and the establishment of new solute–solvent interactions.     

Ionic liquid 1-ethyl-3-methylimidazolium acetate: an attractive solvent for native chemical ligation of peptides

The ionic liquid 1-ethyl-3-methylimidazolium acetate ([C₂mim][OAc]) was successfully used as alternative solvent for native chemical ligation of peptide fragments to produce model peptide LYRAXCRANK (X = G, A, L, N, Q, K, and F). The commonly used buffer system including thiol additives such as thiophenol and benzyl mercaptan can be replaced by the nontoxic ionic liquid [C₂mim][OAc]. In addition to improving the solubility of the peptides in [C₂mim][OAc], yields and rates of the ligation reactions were found to be efficiently enhanced.     

The salting-out effect and phase separation in aqueous solutions of tri-sodium citrate and 1-butyl-3-methylimidazolium bromide

The aim of this work is to obtain further evidence about the salting-out effect produced by the addition of tri-sodium citrate to aqueous solutions of water miscible ionic liquid 1-butyl-3-methylimidazolium bromide ([C₄mim][Br]) by evaluating the effect of tri-sodium citrate on the thermodynamic properties of aqueous solutions of this ionic liquid. Experimental measurements of density and sound velocity at different temperatures ranging from (288.15 to 308.15) K, the refractive index at 308.15 K and the liquid–liquid phase diagram at different temperatures ranging from (288.15 to 338.15) K for aqueous solutions containing 1-butyl-3-methylimidazolium bromide ([C₄mim][Br]) and tri-sodium citrate (Na₃Cit) are taken. The apparent molar volume of transfer of [C₄mim][Br] from water to aqueous solutions of Na₃Cit have positive values and it increases by increasing salt molality. Although at high IL molality, the apparent molar isentropic compressibility shows similar behaviour with that of the apparent molar volume. However at low concentrations of IL, the apparent molar isentropic compressibility of transfer of [C₄mim][Br] from water to aqueous solutions of Na₃Cit have negative values. The effects of temperature and the addition of Na₃Cit and [C₄mim][Br] on the liquid–liquid phase diagram of the investigated system have been studied. It was found that an increase in temperature caused the expansion of the one-phase region. The presence of Na₃Cit triggers a salting-out effect, leading to significant upward shifts of the liquid–liquid de-mixing temperatures of the system. The effect of temperature on the phase-forming ability in the system investigated has been studied based on a salting-out coefficient obtained from fitting the binodal values to a Setschenow-type equation for each temperature. Based on cloud point values, the energetics of the clouding process have been estimated and it was found that both of entropy and enthalpy are the driving forces for biphasic formation.     

The synthesis of Fe-containing ionic liquid and its catalytic performance for the dehydration of fructose

Four Fe-containing ionic liquids (ILs) were synthesized by coupling of conventional imidazole ionic liquids [C_xmim]Cl (x = 4, 8, 12, 16) with FeCl₃ and were characterized by FT-IR, Raman, ESI–MS and TG. All of the Fe-containing ILs were applied to the conversion of fructose into 5-hydroxymethylfurfural (HMF) in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) subsequently and the result showed that [C₁₆mim]FeCl₄ exhibited excellent catalytic performance. Then the different reaction parameters with [C₁₆mim]FeCl₄ as catalyst were studied in detail. A 92.8% yield of HMF was obtained with 0.03 g [C₁₆mim]FeCl₄ and 0.1 g fructose in 1.0050 g [Bmim]Cl at 80 °C for 40 min in fructose/[Bmim]Cl solution.     

Luminescent Soft Material: Two New Europium‐Based Ionic Liquids

Two new Eu‐based ionic liquid systems, [C₄mim][DTSA] : [Eu(DTSA)₃] and 2[C₄mim] [DTSA] : [Eu(DTSA)₃] were synthesized at 120° under inert conditions from 1‐butyl‐1‐methylimidazolium ditoluenesulfonylamide ([C₄mim][DTSA]). The identity and purity of the synthesized compounds were confirmed by elemental analysis, IR, Raman, and ¹H‐NMR spectroscopy. As they solidify below 100° as glasses they qualify as ionic liquids. Fluorescence measurements show that the materials exhibit a strong red luminescence of high color purity. Therefore, they have the potential to be used for optical applications such as in emission displays.     

Separation of no-carrier-added 109Cd from natural silver target using RTIL 1-butyl-3-methylimidazolium hexafluorophosphate

The room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate [C₄mim][PF₆] has various applications in the separation of a range of metal ions replacing volatile and toxic traditional organic solvents in liquid–liquid extraction systems. In this study, the RTIL [C₄mim][PF₆] was used to separate no-carrier-added (NCA) ¹⁰⁹Cd from α-particle irradiated Ag target. A natural Ag foil was bombarded by 30 MeV α-particles to produce ¹⁰⁹Cd. After the decay of all co-produced short-lived products, NCA ¹⁰⁹Cd was separated from the bulk Ag using [C₄mim][PF₆] as extractant from HNO₃ medium. Ammoniumpyrrolidine dithiocarbamate (APDC) was used as a complexing agent. At the optimum condition, 3 M HNO₃, 0.01 M APDC in presence of [C₄mim][PF₆], ~99 % bulk Ag was extracted to the IL phase, leaving NCA ¹⁰⁹Cd in the aqueous phase. The amount of Ag became negligibly small after re-extraction in the same condition. The ionic liquid was recovered by washing it with 1 M HCl.     

Investigations on the Physicochemical and Radiolytic Degradation Properties of Tri-<Emphasis Type="Italic">n</Emphasis>-butylphosphate–Ionic Liquid in the Presence of Nitric Acid

Tri-n-butylphosphate (TBP) in an ionic liquid (IL) has been proposed as a suitable alternative for the solvent extraction of actinides from nitric acid solutions. This paper reports the detailed investigations on the physicochemical and hydrodynamic properties of the solvent system containing TBP in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C₄mim][NTf₂]) IL. The properties such as density, viscosity, phase separation time (PST), etc., were measured for irradiated and unirradiated solvent phases composed of TBP, [C₄mim][NTf₂] and 1.1 mol·L^–1 TBP in [C₄mim][NTf₂]. The results are compared with the values obtained in acid-equilibrated IL phases. ATR–FTIR spectroscopy and dynamic light scattering measurement of the IL phase were employed to characterize the interactions among the IL, TBP and nitric acid medium, and the aggregate size of the adduct formed in the IL phase.     

Tri-<Emphasis Type="Italic">n</Emphasis>-butyl phosphate–ionic liquid mixtures for Li<Superscript>+</Superscript> extraction from Mg<Superscript>2+</Superscript>-containing brines at 303–343 K

Extraction of Li⁺ ions from salt lake brine into an ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C₂mim][NTf₂]) mixed with tri-n-butyl was investigated. The extraction mechanism was been studied using UV–Vis spectroscopy From the temperature dependence data, the thermodynamic functions values (ΔG°, ΔH°, and ΔS°) were calculated. Furthermore, stripping of metals from ionic liquid phase to an aqueous phase by hydrochloric acid was accomplished.     

Effect of simple electrolytes on the thermodynamic properties of room temperature ionic liquids in aqueous solutions

Density, sound velocity and conductivity measurements are carried out on 1-heptyl-3-methylimidazolium bromide ([C₇mim][Br]) in pure water and in aqueous solutions of sodium di-hydrogen citrate, di-sodium hydrogen citrate and tri-sodium citrate over a range of temperatures at atmospheric pressure. The experimental density and sound velocity data are used to calculate the apparent molar volume and isentropic compressibility as a function of temperature and concentration. The effects of temperature and charge on the anion of sodium citrate salts on the apparent molar volume and isentropic compressibility of [C₇mim][Br] are studied. It was found that both of the apparent molar volume and isentropic compressibility of [C₇mim][Br] in aqueous sodium citrate solutions are larger than those in pure water and increase by increasing temperature. The effects of temperature and charge on the anion of sodium citrate salts on the conductivity behavior of the investigated IL solutions are also studied.     

(Vapour + liquid) equilibria,volumetric and compressibility behaviour of binary and ternary aqueous solutions of 1-hexyl-3-methylimidazolium chloride,methyl potassium malonate,and ethyl potassium malonate

(Vapour + liquid) equilibrium data (water activity, vapour pressure, osmotic coefficient, and activity coefficient) of binary aqueous solutions of 1-hexyl-3-methylimidazolium chloride ([C₆mim][Cl]), methyl potassium malonate, and ethyl potassium malonate and ternary {[C₆mim][Cl] + methyl potassium malonate} and {[C₆mim][Cl] + ethyl potassium malonate} aqueous solutions were obtained through the isopiestic method at T = 298.15 K. These results reveal that the ionic liquid behaves as surfactant-like and aggregates in aqueous solutions at molality about 0.4 mol · kg⁻¹. The constant water activity lines of all the ternary systems investigated show small negative deviations from the linear isopiestic relation (Zdanovskii–Stokes–Robinson rule) derived using the semi-ideal hydration model. The density and speed of sound measurements were carried out on solutions of methyl potassium malonate and ethyl potassium malonate in water and of [C₆mim][Cl] in aqueous solutions of 0.25 mol · kg⁻¹ methyl potassium malonate and ethyl potassium malonate at T = (288.15 to 308.15) K at atmospheric pressure. From the experimental density and speed of sound data, the values of the apparent molar volume, apparent molar isentropic compressibility and excess molar volume were evaluated and from which the infinite dilution apparent molar volume and infinite dilution apparent molar isentropic compressibility were calculated at each temperature. Although, there are no clear differences between the values of the apparent molar volume of [C₆mim][Cl] in pure water and in methyl potassium malonate or ethyl potassium malonate aqueous solutions, however, the results show a positive transfer isentropic compressibility of [C₆mim][Cl] from pure water to the methyl potassium malonate or ethyl potassium malonate aqueous solutions. The results have been interpreted in terms of the solute–water and solute–solute interactions.     

Investigation of the Role of Ionic Liquids in Tuning the p<Emphasis Type="Italic">K</Emphasis><Subscript>a</Subscript> Values of Some Anionic Indicators

The effect of imidazolium-based ionic liquids, ([C₁₂mim][Cl] and [C₈mim][Cl]), on the acid-base equilibria of two sulfonated indicators has been studied. The presence of ILs leads to decreased pK _a values because of the stronger electrostatic interaction of cationic ILs with the basic forms of the indicators with more negative charge. The longer alkyl side chain of [C₁₂mim][Cl] compared to [C₈mim][Cl] results in stronger hydrophobic interaction of this IL with the basic forms of the dyes leading to a more effective decrease in the pK _a values. Also, the transition points and transition intervals of the acid-base titration curves of the indicators were affected by the presence of ILs. It was found that the IL interaction with acid-base indicators also results in sharpening the acid-base titration curves of the indicators. From these observations, it is concluded that the presence of ILs can tune the pK _a values of indicators. All the experiments were performed spectrophotometrically and the results were obtained using curve fitting methods.     

Effect of a copolymer poly(4-styrenesufonic acid-co-maleic acid) sodium salt on aggregation behavior of surface active ionic liquid 1-tetradecyl-3-methylimidazolium bromide and structurally similar conventional surfactant tetradecyltrimethylammonium bromide in aqueous media

The complex formation of anionic copolymer poly(4-styrenesufonic acid-co-maleic acid) sodium salt (PSSA-co-MA) with surfactant tetradecyltrimethylammonium bromide (TTAB) and surface active ionic liquid (SAIL) 1-tetradecyl-3-methylimidazolium bromide ([C₁₄mim][Br]) has been studied in aqueous media by utilizing various techniques such as tensiometry, conductometry and fluorimetry. Conductometric and tensiometric curve of all the investigated systems demonstrate four break points corresponding to four transition states. All the thermodynamic and surface properties of surfactant-polyelectrolyte systems have been determined by conductance and surface tension measurements respectively. The value of cmc decreases with increasing the concentration of polyelectrolyte for studied systems. But it has been observed that, the lowering in cmc values is more in [C₁₄mim][Br]-PSSA-co-MA system than TTAB-PSSA-co-MA system, although the differences in cmc are not much significant. The lowering in cmc of [C₁₄mim][Br]-PSSA-co-MA system shows that ionic attractions between cationic head group [C₁₄mim]⁺ and anionic parts (SO₃^? and COOH), are stronger than those in TTA⁺ and anionic parts (SO₃^? and COOH). The results indicated that the [C₁₄mim][Br]-PSSA-co-MA complexes are comparatively more surface active than TTAB-PSSA-co-MA complexes. The fluorescence probe behaviour also confirms cmc value and provides aggregation number (N_agg). Finally all the findings of [C₁₄mim][Br] and TTAB have been compared.     

Effect of addition of hydrophilic ionic liquid 3-methyl-1-pentylimidazolium tetrafluoroborate ([C5mim][BF4]) on an aqueous solution of triton X-100

The effect of addition of 3-methyl-1-pentylimidazolium tetrafluoroborate ([C₅mim][BF₄]) on the micellization of a nonionic surfactant, Triton X-100 (TX-100), has been investigated. The techniques employed to study the aggregation behavior are fluoremetry, dynamic light scattering (DLS), and transmission electron microscopy (TEM) and the concentration range covered is 0–2?wt% [C₅mim][BF₄]. The probes, viz. pyrene and pyrene-1-carboxaldehyde (PyCHO), have been used for fluorescence analysis. According to the findings, the addition of pentyl-chained ionic liquid (IL) to aqueous TX-100 results in a dramatic increase in critical micelle concentration (cmc) decrease in micellar size, and aggregation number pointing toward an overall “unfavorable” aggregation process.     

A Novel Room Temperature Ionic Liquid Extraction Spectrophotometric Determination of Trace Germanium in Natural Water with Methybenzeneazosalicylfluorone

Abstract

This paper describes a highly sensitive and selective extraction spectrophotometric method for determination of trace germanium in natural water with new a chromogenic reagent methybenzeneazosalicylfluorone abbreviated as MBASF, in which a typical room temperature ionic liquid, 1‐butyl‐3‐methylimidazolium hexafluorophosphate abbreviated as [C₄mim][PF₆] was used as novel medium for liquid/liquid extraction of germanium(IV). In the presence of TritonX‐100, MBASF reacted with germanium(IV) to form a red complex rapidly, the complex was then extracted into the [C₄mim][PF₆] phase, the absorbance of the complex in ionic liquid at 496 nm was recorded and used to determine trace germanium(IV). The apparent molar absorptivity of the complex and the detection limit for the real sample were found to be 3.12×10⁶ L mol^?1 cm^?1 and 0.2 ng mL^?1, respectively. The absorbance of the complex at 496 nm increases linearly with the concentration up to 4 µg of germanium (IV) in 250 mL of aqueous solution. The interference study show the determination of germanium is free from the interference of almost all positive and negative ions found in the natural water samples. The determination of germanium in natural water was carried out by the present method and electrothermal atomic absorption spectrometry (AAS). The results were satisfactorily comparable so that the applicability of the proposed method was confirmed using the real samples. Moreover, the extraction mechanism with the ionic liquid system was also investigated. We think the extraction performance of the ionic liquid system is a combination of ion‐pairing effect between imidazolium cation and basic solute in the aqueous phase with the dissolution of polar molecule in ionic liquid phase. A wise choice of the appropriate combination of anion with imidazolium cation hydrophobicity allows playing with solute selectivity.     

SET‐LRP of acrylonitrile in ionic liquids without any ligand

Use of ionic liquids as reaction media was investigated in the design of an environmentally friendly single electron transfer‐living radical polymerization (SET‐LRP) for acrylonitrile (AN) without any ligand by using Fe(0) wire as catalyst and 2‐bromopropionitrile as initiator. 1‐Methylimidazolium acetate ([mim][AT]), 1‐methylimidazolium propionate ([mim][PT]), and 1‐methylimidazolium valerate ([mim][VT]) were applied in this study. First‐order kinetics of polymerization with respect to the monomer concentration, linear increase of the molecular weight, and narrow polydispersity with monomer conversion showed the controlled/living radical polymerization characters. The sequence of the apparent polymerization rate constant of SET‐LRP of AN was k_app ([mim][AT]) > k_app ([mim][PT]) > k_app ([mim][VT]). The living feature of the polymerization was also confirmed by chain extensions of polyacrylonitrile with methyl methacrylate. All three ionic liquids were recycled and reused and had no obvious effect on the controlled/living nature of SET‐LRP of AN. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Physical Properties of the Ternary Mixture Ethanol+Water+1-Butyl-3-Methylimidazolium Chloride at 298.15 K

In this work densities, refractive indices, speeds of sound and isentropic compressibilities of the ternary mixture ethanol+water+1-butyl-3-methylimidazolium chloride ([C₄mim][Cl]), and of the binary subsystems containing the ionic liquid, have been measured at 298.15 K and atmospheric pressure.