Ionic liquid salt bridge with low solubility of water and stable liquid junction potential based on a mixture of a potential-determining salt and a highly hydrophobic ionic liquid

A new type of ionic liquid salt bridge (ILSB) based on a mixture of pentyltripropylammonium bis(pentafluoroethanesulfonyl)amide, [N(3335)(+)][C(2)C(2)N(-)], and heptadecafluorodecyltrioctylphosphonium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, [TOPH(+)][TFPB(-)], shows a stable phase-boundary potential (Δ(IL)(W)φ) between the ILSB and an aqueous solution of MCl (M = H(+), Li(+), Na(+), and K(+)) over the concentration range from 0.05 mM to 0.5 M with an averaged excursion in 1 h of ±0.3 mV. The reproducibility of Δ(IL)(W)φ is ±0.6 mV on average (95% confidence interval) in KCl solutions in this concentration range. The mixing of the two different types of salts not only increases the stability of the phase-boundary potential but provides us with more freedom in selecting potential-determining salts to design and customize ILSBs for different purposes.     

Synthesis of PbS nanocubes using an ionic liquid as the solvent

Lead sulfide (PbS) is a major ore mineral of lead and an important semiconductor. The small band gap and large exciton Bohr radius make PbS an interesting system for studying the effect of size confinement. The precise control of their size and size distribution is an important goal of modern materials chemistry. In this work, lead sulfide (PbS) nanocubes have been successfully synthesized in an ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF₆) (ILs). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed the cubic morphology of the synthesized nanocrystals with the length about 100 nm. X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) showed the nanocubes were cubic PbS with a lattice constant of 5.93 Å.     

A non-ideal model for predicting the effect of dissolved salt on the flash point of solvent mixtures

Flash point is one of the major quantities used to characterize the fire and explosion hazard of liquids. Herein, a liquid with dissolved salt is presented in a salt-distillation process for separating close-boiling or azeotropic systems. The addition of salts to a liquid may reduce fire and explosion hazard. In this study, we have modified a previously proposed model for predicting the flash point of miscible mixtures to extend its application to solvent/salt mixtures. This modified model was verified by comparison with the experimental data for organic solvent/salt and aqueous-organic solvent/salt mixtures to confirm its efficacy in terms of prediction of the flash points of these mixtures. The experimental results confirm marked increases in liquid flash point increment with addition of inorganic salts relative to supplementation with equivalent quantities of water. Based on this evidence, it appears reasonable to suggest potential application for the model in assessment of the fire and explosion hazard for solvent/salt mixtures and, further, that addition of inorganic salts may prove useful for hazard reduction in flammable liquids.     

溴代聚苯醚膜对有机液/水混合体系的渗透汽化分离

对聚２,６－二甲苯撑氧（ＰＰＯ）进行了溴代反应,制备的溴代ＰＰＯ（简称ＢＰＰＯ）均质膜,以氨水进行化学交联后,表征了其对氯代烃如二氯甲烷、氯仿、氯苯及乙酸乙酯等的水溶液的渗透汽化（ＰＶ）特性;研究了ＢＰＰＯ膜交联性质与其ＰＶ特性间的关系,并进行了理论解释 。     

聚4—甲基戊烯—1对有机液／水混合体系的渗透汽化分离

以结晶性聚合物聚4－甲基戊烯－1（PMP）为膜材质,制备了PMP均质膜,研究了其分子结构与其对二氯甲烷、三氯甲烷和1,2－二氯乙烯等氯代烃有机液／水混合体系的渗透汽化（PV）特性间的关系,并进行了理论解释。     

Determination of the activity of hydrogen ions in dilute sulfuric acids by use of an ionic liquid salt bridge sandwiched by two hydrogen electrodes

The activities of hydrogen ions in 20-200 μmol dm(-3) H(2)SO(4) solution were estimated by use of an ionic liquid salt bridge (ILSB), made of tributyl(2-methoxyethyl)phosphonium bis(pentafluoroethanesulfonyl)amide (TBMOEPC(2)C(2)N), sandwiched by two hydrogen electrodes. The experimental pH values (pH = -log a(H), where a(H) is the activity of hydrogen ions) were in good agreement, within 0.01 pH unit, with those calculated using the Pitzer model. The difference between the experimental and theoretical pH values at 50 μmol dm(-3) H(2)SO(4) solution was much smaller than that obtained by use of a glass electrode in combination with a reference electrode with a concentrated KCl salt bridge. The source of the small deviation can be explained by the residual diffusion potential due to the dissolution of TBMOEPC(2)C(2)N in the H(2)SO(4) solution (W) and the resultant increase in the ionic strength of W. The use of a reference electrode equipped with an ILSB opens the way to accurately estimate the pH in dilute aqueous solutions, for which we have not had effective means.     

Damped response of an axially excited rotating liquid bridge in zero-gravity

Summary The response of a solidly rotating finite liquid bridge due to axial excitation exhibits for frictionless liquid at the resonances singularities. For the experimenter in a spacelabmission the actual resonance amplitude is of quite some importance. For this reason damping, that has to be measured in ground tests, has been introduced into the results of the response.Notation a radius of the liquid bridge - h length of the liquid bridge - I ₀,I ₁ modified Besselfunctions - J ₀,J ₁ Besselfunctions - r, ,z polar coordinates - t time - excitation amplitude - elliptic case - hyperbolic case - abbreviation - damping factor of liquid - (z, t) free surface displacement - =² – ² surface tension - surface tension - liquid density - ₀ rotational speed of liquid bridge - forcing frequency of axial excitation - natural frequency of liquid bridge With 2 Figures     

Ionic liquid modified mesoporous silica (SAB-15) as an effective polysulfide reservoir for high-performance lithium sulfur batteries

To restrict the polysulfide migration effectively, the fabrication of sulfur host material with strong polysulfide adsorption is necessary. Herein, we grafted the cation on SBA-15 surface to achieve the high-efficiency polysulfide reservoir through electrostatic force and the derived Im-SBA-15/CNT hybrid could exhibit a promising application potential as a host material for sulfur cathode owing to the strong polysulfide adsorption of Im-SBA-15 and the successful electron conduction of CNT. As a result, the Im-SBA-15/CNT/S composite delivers a superior electrochemical performance. Even after 350 cycles, Im-SBA-15/CNT/S cathode also could show a capacity of 682.3 mAh/g_sulfur with no obvious capacity fading. This work demonstrates a promising polysulfide suppression strategy for high-performance sulfur cathode.     

Characterization of pH in liquid mixtures of methanol/H2O/CO2

The presence of H2O and CO2 in enhanced-fluidity liquids changes the pH in these mixtures due to the formation of carbonic acid. The acid-base equilibria in enhanced-fluidity liquids will also be affected by the reduction in the dielectric constant with the addition of CO2. The pH of enhanced-fluidity liquid mixtures at room temperature was determined from the UV/visible absorption spectra of several pH indicators. pH values of methanol/H2O/CO2 mixtures with CO2 proportions as high as 19.2 mol% are reported. The effect of adding buffer to methanol/H2O/CO2 mixtures on pH was also studied. It was also shown that pressure variation did not significantly influence the pH of enhanced-fluidity liquids.     

熔融盐法合成锂离子电池正极材料LiNiO2的研究

在空气气氛中,采用熔融盐法制备出了锂离子电池正极材料LiNiO2.差热-热重曲线分析表明:629℃就已经反应完全.XRD分析表明:700℃反应26h制得的LiNiO2具有最完整的层状结构.电性能测试表明所得正极材料放电比容量较好.     

Advantages and limitations of reference electrodes with an ionic liquid junction and three-dimensionally ordered macroporous carbon as solid contact

Liquid-junction-free reference electrodes that contact the sample through an ionic-liquid-doped, hydrophobic polymer membrane have attracted attention because they offer an alternative to reference electrodes with conventional salt bridges. In this work, liquid-junction-free reference electrodes were developed using plasticized poly(vinyl chloride) membranes doped with the ionic liquid (IL) 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide. Three-dimensionally ordered macroporous (3DOM) carbon substrates infused with this ionic liquid phase were used as solid contacts for these reference membranes. As in prior work with ionophore-based 3DOM carbon-contact ion-selective electrodes, the long-term stability of the liquid-junction-free reference electrodes was excellent, with potential drifts as low as 42 μV/h over 26 days. Successful measurements of pH in milk were performed and, to the best of our knowledge, are the first example of the use of liquid-junction-free reference electrodes in complex real-life samples. A thorough analysis of their performance at low pH revealed protonation of the ionic liquid anion (L(-)) and formation of LHL(-) type of associates in the reference electrode membrane, effects not observed in prior work. Also, when reference membranes were mounted into conventional electrode bodies with inner filling solutions that contained no ionic liquid ions, zero-current ion fluxes across the sample/membrane interface occurred, as previously only seen for ionophore-doped ion-selective membranes. Understanding these effects will be crucial to the design of liquid-junction-free reference electrodes suitable for other applications.     

Methods of determining the thermal-diffusion constant in liquid mixtures

The article discusses methods for determining Soret coefficients in highly diluted solutions and liquid isotope mixtures.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 38, No. 6, pp. 1066–1076, June, 1980.     

Viscosity of liquid lithium by an oscillating-cup viscometer in the temperature range 464–923 K

The liquid lithium has been proposed as a blanket substance of a D-T fusion reactor. Among the previously published viscosity data of liquid lithium by different authors, a sizable discrepancy is observed. In the present study, the viscosity of liquid lithium was measured by an oscillating-cup viscometer in the temperature range from 464 to 923 K. It was concluded that the disagreement among the previous studies was owing to the difference of the theory used for calculating the viscosity and also to the influence of the corrosion of the container wall. It was shown that recalculation of values in previous studies with the aid of Kestin-Newell equation, the equation used in the present study, would show reasonable agreement with the present results. The accuracy of the present measurements was estimated as ±3%.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Chiral ionic liquid that functions as both solvent and chiral selector for the determination of enantiomeric compositions of pharmaceutical products

We have successfully synthesized both enantiomers of a novel chiral ionic liquid, (R)- and (S)-[(3-chloro-2-hydroxypropyl) trimethylammonium][bis((trifluoromethyl)sulfonyl)amide] ((R)- and (S)-[CHTA]+[Tf2N]-) in optically pure form by a simple ion exchange reaction from corresponding chloride salts that are commercially available. In addition to the ease of preparation, this chiral IL has relatively high thermal stability (up to 300 degrees C), is liquid at room temperature (glass transition temperature of -58.4 degrees C), and exhibits strong enantiomeric recognition. The high solubility power and strong enantiomeric recognition ability make it possible to use this chiral IL to solubilize an analyte and to induce diastereomeric interactions for the determination of enantiomeric purity. In fact, we have successfully developed a novel method based on the near-infrared technique with this chiral IL serving both as solvent and as a chiral selector for the determination of enantiomeric purity. Enantiomeric compositions of a variety of pharmaceutical products and amino acids with different shape, size, and functional groups can be sensitively (milligram concentration) and accurately (enantiomeric excess as low as 0.6%) determined by use of this method.     

Ammonium dodecyl sulfate as an alternative to sodium dodecyl sulfate for protein sample preparation with improved performance in MALDI mass spectrometry

Sodium dodecyl sulfate (SDS) is a strong surfactant that is widely used in protein sample preparation. While protein and peptide samples containing up to approximately 1% SDS can be analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) using a two-layer matrix/sample deposition method, the presence of SDS in a protein sample generally degrades mass resolution and mass measurement accuracy. This degradation in performance is found to be related to the formation of sodium-protein adducts in the MALDI process. If the instrument resolving power is insufficient to separate these adduct peaks from the protonated molecular ion peak, peak broadening is observed in the protein molecular ion region, and as a result, the peak centroid shifts to a higher mass. In this work, we present a method using ammonium dodecyl sulfate as a viable alternative to SDS for protein sample preparation with much improved MALDI MS performance. Three non-sodium-based dodecyl sulfate surfactants, ammonium dodecyl sulfate (ADS), hydrogen dodecyl sulfate, and tris(hydroxymethyl)aminomethane dodecyl sulfate were investigated. Of the three surfactants tested, it is found that ADS gives the best performance in MALDI. For proteins with moderate molecular masses (i.e., up to approximately 25 kDa), the presence of ADS in a protein sample does not result in significant degradation in mass resolution and accuracy, and the protonated molecular ion peak is the dominant peak in the MALDI spectrum. The ammonium adduct ions dominate the MALDI spectra when the protein mass exceeds approximately 25 kDa; however, ADS still gives better results than SDS. The behavior of ADS in gel electrophoresis was also investigated. It is shown that cell extracts dissolved in ADS can be separated by normal SDS-polyacrylamide gel electrophoresis by simply mixing them with the SDS sample buffer. The application of ADS as the surfactant for protein solubilization with improved performance in MALDI analysis is demonstrated in the study of a detergent insoluble fraction from a Raji/CD9 B-cell lymphocyte lysate.     

Dispersion of the dielectric permittivity in mixtures of nematic liquid crystals

The spectrum of relaxation time for the low-frequency dispersion has been found to become wider in mixtures of nematic liquid crystals, which can be interpreted as a superposition of two Debye relaxation mechanisms.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 37, No. 1, pp. 104–109, July, 1979.     

有机液/有机液渗透汽化分离膜的研究进展

根据不同的有机液／有机液混合物体系，对已有的渗透汽化膜材质进行了系统综述，并对各种膜的分离性能答了全面的阐述。     

Approximate evaluation of the thermal diffusion constant in liquid isotopic mixtures

An attempt is made to derive a semiempirical dependence for the thermal diffusion constant in liquid isotopic mixtures on the basis of data available in the literature.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 15, No. 6, pp. 1014–1018, December, 1968.