Characterization of room-temperature ionic liquids by the Abraham model with cation-specific and anion-specific equation coefficients

Gas-to-RTIL (room-temperature ionic liquid) partition coefficients have been compiled for 592 different solute-RTIL combinations. These partition coefficients were converted into water-to-RTIL partition coefficients using the corresponding gas-to-water partition coefficients. Both sets of partition coefficients were analyzed using the Abraham solvation parameter model with cation-specific and anion-specific equation coefficients. The derived equations correlated the experimental gas-to-RTIL and water-to-RTIL partition coefficient data to within 0.10 and 0.14 log units, respectively. The 8 sets of calculated cation-specific equation coefficients and 4 sets of calculated anion-specific equation coefficients can be combined to yield expressions capable of predicting the partition coefficients of solutes in 32 different RTILs.     

Linear free energy relationship (LFER) correlations for the solubilising characterisation of room temperature ionic liquids containing triethylsulphonium and 1-butyl-1-methylpyrrolidinium cations

Gas-to-room temperature ionic liquid (RTIL) partition coefficients have been compiled from the published literature for solutes dissolved in triethylsulphonium bis(trifluoromethylsulphonyl)imide, {[E₃S]⁺[(Tf)₂N]^?}, and in 1-butyl-1-methylpyrrolidinium trifluoromethanesulphonate, {[BMPyr]⁺[Trif]^?}. These partition coefficients were converted into water-to-RTIL partition coefficients using the corresponding gas-to-water partition coefficients. Both sets of partition coefficients were analysed using the Abraham model with cation-specific and anion-specific equation coefficients. Equation coefficients are reported for the triethylsulphonium and 1-butyl-1-methylpyrrolidinium cations. The calculated cation coefficients can be combined with our previously determined eight sets of anion-specific equation coefficients to yield expressions capable of predicting the partition coefficients of solutes in 16 different RTILs.     

Linear free energy relationship correlations for the solubilising characterisation of room temperature ionic liquids containing 1-hexyloxymethyl-3-methylimidazolium and 1,3-dihexyloxymethylimidazolium cations

Gas-to-room temperature ionic liquid (RTIL) partition coefficients have been compiled from the published literature for solutes dissolved in 1-hexyloxymethyl-3-methylimidazolium bis(trifluoromethylsulphonyl)imide, {[HxomMIm]⁺[(Tf)₂N]^?}, and in 1,3-dihexyloxymethylimidazolium bis(trifluoromethylsulphonyl)imide, {[(Hxom)₂Im]⁺[(Tf)₂N]^?}. These partition coefficients are converted into water-to-RTIL partition coefficients using the corresponding gas-to-water partition coefficients. Both sets of partition coefficients are analysed using the Abraham model with cation-specific and anion-specific equation coefficients. The equation coefficients are reported for the 1-hexyloxymethyl-3-methylimidazolium and 1,3-dihexyloxymethylimidazolium cations. The calculated cation coefficients can be combined with our previously determined nine sets of anion-specific equation coefficients to yield expressions capable of predicting the partition coefficients of solutes in 18 different RTILs.     

Form of multicomponent Fickian diffusion coefficients matrix

The form of multicomponent Fickian diffusion coefficients matrix in thermodynamically stable mixtures is established based on the form of phenomenological coefficients and thermodynamic factors. While phenomenological coefficients form a symmetric positive definite matrix, the determinant of thermodynamic factors matrix is positive. As a result, the Fickian diffusion coefficients matrix has a positive determinant, but its elements — including diagonal elements — can be negative. Comprehensive survey of reported diffusion coefficients data for ternary and quaternary mixtures, confirms that invariably the determinant of the Fickian diffusion coefficients matrix is positive.     

萘二磺酸钠盐的等压渗透系数和活度系数

芳基磺酸及其盐是化学工业、染料、清洁剂和离子交换树脂等许多方面使用得非常广泛的化学材料之一。在有机化合物分子上引进磺酸基团可大大改善化合物在溶剂中的可溶性等性质.磺酸基在化学和物理现象上所引起的作用已有许多工作者进行过研究。文献[1.2.3]报导了一些苯磺酸及其盐水溶液渗透系数和活度系数的测量结果.为了比     

298.15K下果糖水溶液中卤化钠单个离子活度系数

利用离子选择性电极和甘汞电极分别测定了NaX+果糖+水体系中的单个离子活度系数和离子平均活度系数.结果表明:基于Debye-Hückel扩展方程和Pitzer方程求得的单个离子活度系数彼此一致;由单个离子加合求得的与直接测定的平均离子活度系数也很一致;随果糖含量的增大,单个离子活度系数减小;在相同混合溶剂(果糖+水)和相等电解质浓度条件下,对于不同的NaX,Na+的活度系数大小顺序为NaFNaClNaBr.基于离子间的相互作用对结果进行了讨论.     

Activity Coefficients of Individual Ions from Titration Data

It is shown that the activity coefficients of the anions resulting from the dissociation of a weak polyprotic acid can be obtained from titration data. Activity coefficients are determined in terms of the activity coefficient of the undissociated acid. The extracted activity coefficients are also dependent on the pH scale adopted in the titration process and are considered as operational coefficients. The computational procedure uses an exact equation representing the titration curve and a nonlinear least-squares fitting procedure. As an illustration, the activity coefficients of the anions of succinic acid are determined. The method also allows study of the variation of the activity coefficients with the ionic strength in a straightforward manner.     

Comment on “Factorizing of a concentration function for the mean activity coefficients of aqueous strong electrolytes into individual functions for the ionic species” by A. Ferse and H.O. Müller

A. Ferse and H.O. Müller have recently presented a mathematical method aimed at subdividing the activity coefficients of electrolytes into functions of individual ionic species; these functions are suggested to be the ionic activity coefficients. By examining the method, it is possible to verify that the peculiar mathematical structure of the functions in question really guarantees a unique result, unlike the usual subdivisions of electrolyte activity coefficients, which admit infinite possibilities for the ionic activity coefficients. But the subsequent step of the reasoning, i.e., that these functions have to be the activity coefficients of the ionic species, is an illation. And indeed, another kind of subdivision in individual functions can be exemplified, whose mathematical structure also guarantees results that are unique and perfectly compatible with all theoretical properties of the ionic activity coefficients. It is concluded that it is impossible to rely on mathematical method to pull the activity coefficients of ions out of the mean activity coefficients of the electrolytes. And hence, the individual functions for the ionic species determined by Ferse and Müller do not represent the ionic activity coefficients and do not have any particular utility.     

等压法装置和焦磷酸钾活度的测定

测量活度的方法很多,等蒸气压法是其中的主要方法之一,我们根据等压法原理设计和安装了一套较简单的实验装置,测量了焦磷酸钾在不同浓度水溶液中的平均活度系数和渗透系数,结果与文献[1]相符,证明实验装置合乎要求。     

Excess virial coefficients with application in data analysis

This paper presents the general expression for excess virial coefficients of binary mixtures in the form of Bartlett's law. Imposing this expression in data reduction to determine mixture virial coefficients provides thermodynamically consistent evaluations of cross virial coefficients. Standard data reduction procedures do not provide values of the mixture and cross virial coefficients that are both consistent and accurate. We illustrate this new technique by analyzing Burnett data and direct density measurements. In addition, we present the general expression for cross virial coefficients under model solution behavior.     

Effect of temperature on the behavior of osmotic and activity coefficients of amides in aqueous solutions

The osmotic coefficients of acetamide, propionamide and butyramide in water were measured at 293.15, 298.15 and 308.15 K using the isopiestic method. The activity coefficients were calculated for the aliphatic amides and the pairwise free energy coefficients for solute-solute interactions were determined according to the McMillan-Mayer theory. The osmotic and activity coefficients of amides are discussed in terms of solute-solute interactions.     

Diffusion of polarizable colloids in electromagnetic fields

Diffusion of polarizable colloids in electromagnetic fields is considered. Extensive and intensive thermodynamic formulations of magnetic and electric polarization energy is used to establish driving forces that generate diffusion of colloids. Effects of concentration, activity coefficient, and interfacial and polarization energies are formulated in terms of corresponding concentration dependent diffusion coefficients. Magnetic and electric diffusion coefficients are defined and it is shown that the former can be made comparable and even larger than ordinary diffusion coefficients of polarizable colloids. Magnetic diffusion coefficients are derived for mono- and polydisperse colloid mixtures relative to the fluid and then are transformed to the dispersion frame of reference. It is shown that ordinary and magnetic diffusion coefficients of polydisperse colloids can be resolved into four and three basic coefficients, respectively.     

Measurement of attenuation coefficients of some dilute solutions at 662 keV

Linear attenuation coefficients of solutions of some compounds in aqueous medium have been measured at 662 keV. From the precisely measured densities of these solutions, mass attenuation coefficients were then obtained. The composition dependence of these mass attenuation coefficients has been successfully used to determine mass attenuation coefficients of the respective solutes which agree very well with the values obtained through XCOM calculations.     

Measurements of molecular and thermal diffusion coefficients in ternary mixtures

Thermal diffusion coefficients in three ternary mixtures are measured in a thermogravitational column. One of the mixtures consists of one normal alkane and two aromatics (dodecane-isobutylbenzene-tetrahydronaphthalene), and the other two consist of two normal alkanes and one aromatic (octane-decane-1-methylnaphthalene). This is the first report of measured thermal diffusion coefficients (for all species) of a ternary nonelectrolyte mixture in literature. The results in ternary mixtures of octane-decane-1-methylnaphthalene show a sign change of the thermal diffusion coefficient for decane as the composition changes, despite the fact that the two normal alkanes are similar. In addition to thermal diffusion coefficients, molecular diffusion coefficients are also measured for three binaries and one of the ternary mixtures. The open-end capillary-tube method was used in the measurement of molecular diffusion coefficients. The molecular and thermal diffusion coefficients allow the estimation of thermal diffusion factors in binary and ternary mixtures. However, in the ternaries one also has to calculate phenomenological coefficients from the molecular diffusion coefficients. A comparison of the binary and ternary thermal diffusion factors for the mixtures comprised of octane-decane-1-methylnaphthalene reveals a remarkable difference in the thermal diffusion behavior in binary and ternary mixtures.     

A method to estimate the Leslie coefficients of liquid crystals based on MBBA data

A new effective approach for estimating the Leslie coefficients of liquid crystals based on MBBA data is presented. Literature values of the temperature-dependent Leslie viscosity coefficients of MBBA are used to fit with the analytical functions of Leslie coefficients based on the Imura and Okano theory, and a set of constants in these functions are determined. The same functions are then applied to two high birefringence liquid crystal mixtures, E7 and UCF-2, to extract their Leslie coefficients based on their order parameters. Using the extracted Leslie coefficients, the simulation results agree very well with the experimental data.     

Combined Diffusion Coefficients in CO<Subscript>2</Subscript> Thermal Plasmas Contaminated with Cu,Fe or Al

Our work aims at the computation of combined diffusion coefficients in CO₂–metal (Cu, Fe, Al) mixtures at a temperature interval of 2000–30,000 K at 0.1 MPa and aims at the investigation of the impact of the concentration and nature of metal vapor (Cu, Fe, Al) on diffusion phenomena. The combined diffusion coefficients have four components, more specifically, combined ordinary diffusion coefficient, combined electric field diffusion coefficient, combined temperature diffusion coefficient and combined pressure diffusion coefficient due to the gradients of the species densities, applied electrical field temperature and pressure. The results indicate that, for Cu and Fe, the combined diffusion coefficients are quite identical under the condition of same metal concentrations (1 and 10% mass concentration). Compared with Cu and Fe under the same metal concentrations (1 and 10%), Al results in a larger enhancement of combined electric field and ordinary diffusion coefficients while smaller enhancement of combined temperature diffusion coefficients. All the combined diffusion coefficients exhibit an upward trend with metal concentrations except for combined electric field, temperature and pressure diffusion coefficients. These three mentioned coefficients are attenuated by the metal vapor above the certain concentration such as, in the case of combined temperature diffusion coefficients, 70% Cu, 70% Fe and 50% Al for CO₂–Cu, CO₂–Fe and CO₂–Al mixtures respectively. Namely, compared with Cu and Fe, less quantity of Al is required to achieve the maximum of combined diffusion coefficients. Maximum peaks for the combined coefficients are shifted to the higher temperature with increasing metal concentrations.     

Coupling coefficients of glass/epoxy laminates under off-axis tensile conditions: Experimental verification

A comprehensive experimental study on the coupling coefficients of unidirectional (UD) and woven fabric glass/epoxy laminates under off-axis tensile loading was conducted in comparison with the theoretical prediction. The capability of the off-axis test to evaluate the elastic constants in the loading direction was reported. Four coupling coefficients were obtained from tests and discussed in comparison with the theoretical prediction. A further comparison of coupling compliance coefficients in compliance matrix was made in order to generalize the influence of off-axis angle on the compliance coefficients. The theoretical prediction agreed well with the experimental data. It is shown that non-monotonic and symmetry phenomena can be observed in the curves of the coupling and compliance coefficients. The results of this experimental study provide a data base of the coupling coefficients of glass/epoxy laminates for engineering application.     

Interrelation between Self-Diffusion,Viscosity, and Optical Properties of Organic Liquids

The possibility of general correlation analysis of the self-diffusion coefficients and dynamic viscosity coefficients of low-molecular-weight liquid organic nonelectrolytes was studied. An attempt was made to obtain common dependences suitable for calculating the self-diffusion and viscosity coefficients.     

Determination of polydimethylsiloxane-air partition coefficients using headspace sorptive extraction

Polydimethylsiloxane-air partition coefficients (K(PDMS-A)) were determined using direct headspace analysis and headspace sorptive extraction (HSSE) with polydimethylsiloxane-coated (PDMS) stir bars. The partition coefficients were investigated for three compounds, p-dichlorobenzene (PDCB), naphthalene and camphor, all of which sublimate at room temperature and find use as moth repellents. In order to determine the K(PDMS-A) values of these compounds, the air concentration and the concentration present on PDMS, both at equilibrium, were measured. The results indicate that PDMS-air partition coefficients are proportional to octanol-air partition coefficients. Thus, the latter could be used to estimate the extraction efficiency of PDMS for these compounds in air. Alternatively, octanol-air partition coefficients for organic compounds could be estimated from the PDMS-air partition coefficient values. As expected, the PDMS-air (or octanol-air) partition coefficient increased with decreasing temperature. Importantly, the partition coefficients determined at saturated vapor pressures were lower than the values determined at lower analyte concentrations, with the differences being greater for compounds with larger partition coefficients. Consequently, caution should be exercised when applying K(PDMS-A) values determined at high analyte concentrations to measurements at lower concentrations, especially when the partition coefficients are large.     

Molecular and thermal diffusion coefficients of alkane-alkane and alkane-aromatic binary mixtures: effect of shape and size of molecules

New molecular and thermal diffusion coefficients of binary mixtures of normal decane-normal alkanes and methylnaphthalene-normal alkanes are measured at atmospheric pressure and T = 25 degrees C. The normal alkanes used in this work include nC5-nC20. Thermal diffusion coefficients were measured in a thermogravitational column. Molecular diffusion coefficients were measured using an open-ended capillary tube technique. Results show a significant effect of molecular shape and size on thermal and molecular diffusion coefficients. Molecular diffusion coefficients show a monotonic behavior in both aromatic-normal alkane and normal decane-normal alkane mixtures. Thermal diffusion coefficients reveal a nonmonotonic trend with molecular size in the normal decane-normal alkane mixtures. This is the first report of the nonmonotonic behavior in the literature. The data presented in this paper provide an accurate self-molecular diffusion coefficient for nC10 from binary data.