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1.
Densities (ρ) and viscosities (η) of different strengths of magnesium sulphate (MgSO4) in varying proportions of formamide (FA) + ethylene glycol as mixed solvents were measured at room temperature. The experimental
values of ρ and η were used to calculate the values of the apparent molar volume, (φ1,), partial molar volume, (φ1,ℴ) at infinite dilution,A- andB-coefficients of the Jones-Dole equation and free energies of activation of viscous flow, (Δμ
1
0*
) and (Δμ
2
0*
), per mole of solvent and solute respectively. The behaviour of these parameters suggests strong ion-solvent interactions
in these systems and also that MgSO4 acts as structure-maker in FA + ethylene glycol mixed solvents. 相似文献
2.
Recent advances in studies of ionic liquids (IL) and ionic liquid–solvent mixtures are reviewed. Selected experimental, simulation, and theoretical results for electrochemical, thermodynamical, and structural properties of IL and IL-solvent mixtures are described. Special attention is paid to phenomena that are not predicted by the classical theories of the electrical double layer or disagree strongly with these theories. We focus on structural properties, especially on distribution of ions near electrodes, on electrical double layer capacitance, on effects of confinement, including decay length of a dissjoining pressure between confinig plates, and on demixing phase transition. In particular, effects of the demixing phase transition on electrochemical properties of ionic liquid–solvent mixtures for different degrees of confinement are presented. 相似文献
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Jessica Padilla‐Pantoja Jose Luis Garcia‐Munoz Bernat Bozzo Zdenek Jirak Javier Herrero‐Martin 《ChemInform》2015,46(6):no-no
Two successive magnetic transitions of Pr0.50Sr0.50CoO3 contrast with the single ferromagnetic transition in other Ln0.50Sr0.50CoO3 compounds. 相似文献
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Polyallenes prepared with the aid of organoaluminum-VOCl3 catalysts appear to exist in three distinct phases: two crystalline phases (I and II) and an amorphous phase. Phase I shows two strong X-ray diffraction peaks at d = 5.62 Å and d = 4.04 Å; phase II has three strong peaks at d = 6.28 Å, d = 5.03 Å, and d = 4.21 Å. The band of the amorphous phase has its maximum at about d = 5.6 Å. 相似文献
6.
Kinematic viscosities were measured for 2-butanone + 2-butanol binary liquid mixtures with a capillary Ubbelohde routine viscometer in the temperature range from 273.15 to 353.15 K at atmospheric pressure, and covering the whole miscibility field (0xi1). Experimental data have been correlated by means of different empirical or semiempirical relationships, such as =(T), =(xi), and =(T, xi). Viscosity deviations, , from ideal behavior are negative at all experimental conditions, confirming that structure breaking effects prevail in the liquids. Furthermore, the thermodynamics of viscous flow and excess Gibbs energy of activation of viscous flow, G*E, have been calculated. As an alternative and complementary approach to such investigations, the fluidity () of this binary system has been analyzed by the modified—Batschinski theory. The results are discussed in terms of the specific molecular interactions between the mixture components. 相似文献
7.
The specific rate constants for the alkaline hydrolysis of formamide were determined in a series of acetone-water mixtures ranging from 0.0% to 70% by weight of the organic solvent and at different temperature, 25°–50°. The rate was found to be larger in water. Addition of acetone appears to cause a change in the solvent structure as concluded from the variation of log k with either 1/D or log[H2O]. The reactivity of the reactants and the activated state seems to be affected differently by a change in the solvent structure. The magnitude of such effect should be considered separately on both the reactants and the activated state in order to account for the increase of the rate as the dielectric constant of the medium is increased. 相似文献
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Taisir T. Khidr 《Journal of Dispersion Science and Technology》2013,34(2):184-192
Nine additives were prepared by esterification of dibasic acid (succinic, adipic, sebacic acid) and polyethylene glycol (Mol.wt.=600, 1000, 4000). These additives were characterized by infrared spectral analysis, average molecular weight and polydispersity index. Their influence on the depression of pour point for two type of paraffin gas oils (G1 and G2) were investigated, blends of paraffin gas oils G1 and G2 by different ratio, when their untreated and treated by additives were evaluated as pour point depressant in comparison with the original paraffin gas oils G1 and G2. The effect of additive type and gas oil composition on wax crystal modification were studied using the photo micrographic analysis. Diethoxylate (eo=182) sebacate with blend gas oil No. 3 has achieved the best performance as pour point depressant. The photo micrographic analysis showed that, the wax morphology was greatly modified to fine dispersed crystals of compact size. A correlation between the pour point depression and the extent of wax modification was detected. 相似文献
11.
Xiaoying Liu Wenlin Ruan Wei Wang Xianming Zhang Yunqi Liu Jingcheng Liu 《Molecules (Basel, Switzerland)》2021,26(13)
Oil and gas wastewater refers to the waste stream produced in special production activities such as drilling and fracturing. This kind of wastewater has the following characteristics: high salinity, high chromaticity, toxic and harmful substances, poor biodegradability, and a difficulty to treat. Interestingly, nanomaterials show great potential in water treatment technology because of their small size, large surface area, and high surface energy. When nanotechnology is combined with membrane treatment materials, nanofiber membranes with a controllable pore size and high porosity can be prepared, which provides more possibilities for oil–water separation. In this review, the important applications of nanomaterials in wastewater treatment, including membrane separation technology and photocatalysis technology, are summarized. Membrane separation technology is mainly manifested in ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). It also focuses on the application of semiconductor photocatalysis technology induced by TiO2 in the degradation of oil and gas wastewater. Finally, the development trends of nanomaterials in oil and gas wastewater treatment are prospected. 相似文献
12.
Aleksandra Zieliska Krzysztof Wjcicki Dorota Klensporf-Pawlik Marta Marzec Massimo Lucarini Alessandra Durazzo Joel Fonseca Antonello Santini Izabela Nowak Eliana B. Souto 《Molecules (Basel, Switzerland)》2022,27(18)
Over the last decades, we have witnessed an increasing interest in food-related products containing vegetable oils. These oils can be obtained either by extraction or by mechanical pressing of different parts of plants (e.g., seeds, fruit, and drupels). Producers of nutraceuticals have ceaselessly searched for unique and effective natural ingredients. The enormous success of argan oil has been followed by discoveries of other interesting vegetable oils (e.g., pomegranate oil) containing several bioactives. This work describes the pomegranate fruit extract and seed oil as a rich source of conjugated linolenic acid as a metabolite of punicic acid (PA), deriving from the omega-5 family (ω-5). Through the chemical characterization of PA, its nutritional and therapeutic properties are highlighted together with the physiological properties that encourage its use in human nutrition. We analyzed the composition of all fatty acids with beneficial properties occurring in pomegranate seed oil using gas chromatography (GC) with flame-ionization detection (FID) analysis combined with Fourier transform infrared spectroscopy (FTIR). Pomegranate seed oil mainly consists of 9,11,13-octadic-trienoic acid (18:3), corresponding to 73 wt % of the total fatty acids. Nine components were identified by GC in PSO, varying between 0.58 and 73.19 wt %. Using midinfrared (MIR) spectroscopy, we compared the composition of pomegranate seed oil with that of meadowfoam seed oil (MSO), which is also becoming increasingly popular in the food industry due to its high content of long chain fatty acids (C20-22), providing increased oil stability. From the results of FTIR and MIR spectroscopy, we found that punicic acid is unique in PSO (73.19 wt %) but not in MSO. 相似文献
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采用聚酰亚胺和磺化聚芳醚砜共混改性的中空纤维膜,研究了在不同操作条件下对压缩空气的脱湿性能,并以此作为吹扫气源,研究了在气流吹扫操作方式下蒸汽渗透法乙醇气相脱水过程,实验结果表明,膜的脱水性能与膜材料的亲水性有关,控制共混比例可以得到综合性能优良的气体脱湿膜。在压缩空气脱湿过程中,提高操作压力和气流回扫比对降低产品气的露点是有利的,在0.35MPa的操作压力下,可得到露点低于-25℃的产品空气。在乙醇气相脱水过程中,采用干燥的吹扫气流并增加吹扫气流的速率对提高水/醇分离系数是十分必要的,当采用合适的操作条件时,改性聚酰亚胺中空纤维膜的水/醇分离系数可达150~200。 相似文献
15.
Joakim Balogh Ulf Olsson Jan Skov Pedersen 《Journal of Dispersion Science and Technology》2013,34(4):497-510
We compare two ternary microemulsions, stabilized by the nonionic surfactant pentaethylene‐glycol‐dodecyl‐ether (C12E5), containing decane or hexadecane. The comparison involves phase behavior and properties of O/W droplet microemulsions investigated with SAXS, static and dynamic light scattering, and NMR. Striking differences are observed. The systems are analyzed in terms of curvature elastic properties of surfactant film. Apart from an increase of the spontaneous curvature, there also appears to be a small but significant increase in the saddle splay constant as the oil chain length is increased. 相似文献
16.
Keio Toi Tomoyasu Ito Isao Ikemoto Tetsuo Kasai 《Journal of Polymer Science.Polymer Physics》1992,30(5):497-503
Sorption rate curves of CO2, N2, and He gases below 1 atm were measured for polyimide films prepared from benzophenone tetracarboxylic dianhydride (BTDA) with 3,5-diaminotoluene trifluoride (DATF), 2,4-diaminotoluene (DAT), m-phenylenediamine (MPD), and diaminobenzoic acid (DABA). The molecular structures of these four polyimides differ only in the substituent groups of the diamine structure. These polyimides exhibit dualmode type sorption isotherms for carbon dioxide that are concave to the pressure axis, typical of glassy polymer/gas system. The apparent diffusion coefficients below 1 atm pressure of carbon dioxide for this series of compounds decrease in the order: BTDA-DATF > BTDA-DAT > BTDA-MPD > BTDA-DABA. A linear relation between the logarithm of the apparent diffusion coefficient and the reciprocal of free volume, calculated by the method of Bondi using density data, is found for these polyimides. However, this tendency is not observed for the other two gases. The activation energies of the apparent diffusion coefficients at 20 cmHg pressure of carbon dioxide increase with increasing cohesive energy density of the polyimides. The energy per mole of free volume elements in a liquidlike structure in each cohesive energy density may be equated to the activation energy and used to calculate the free volume. The values from the activation energy are almost the same as those from Bondi's method. 相似文献
17.
The permeabilities and solubilities of five gases are reported for bisphenol-A polycarbonate (PC), tetramethyl polycarbonate (TMPC), and tetramethyl hexafluoro polycarbonate (TMHFPC) at temperatures up to 200°C. The temperature dependence of permselectivity is discussed in terms of solubility and diffusivity selectivity changes with temperature for CO2/CH4 and He/N2 gas separations. The activation energies for permeation and diffusion and the heats of sorption are also reported for each gas in the three polycarbonates. Analysis of these values provides a better fundamental understanding of the effect of polymer-penetrant interactions and polymer backbone structure on the temperature dependence of the transport and sorption properties of gases in membrane separation processes. Important factors affecting the solubility and diffusivity selectivity losses or gains with increased temperature are also identified through correlation of these data with physical properties of the gases and polymers. These conclusions provide a framework for choosing the most promising membrane materials for particular gas separations at elevated temperatures. © 1994 John Wiley & Sons, Inc. 相似文献
18.
用核磁共振氢谱测量了不同温度(293.15和308.15 K)及压力高达25 MPa下二氧化碳-甲醇混合气相(超临界)及液相区(亚临界)中甲醇(羟基及甲基)的纵向弛豫时间T1,exp。本工作的目的是考察近临界区二氧化碳-甲醇混合物的压力、温度及组成对甲醇弛豫速率的影响,揭示混合物不同相区(气相及液相区)中自旋-晶格弛豫(SLR)过程的机理。此外,还对比研究了等温条件下超临界和亚临界混合气相及液相区中甲醇的SLR速率1/T1,exp随混合物密度的变化规律。研究发现,在本工作所涉及的温度及压力区间,对于纯甲醇或液相区其SLR过程是以偶极-偶极(DD)作用机理为主导,而在气相区SLR过程则是以自旋-转动(SR)作用机理占优势,也即,超临界和亚临界二氧化碳-甲醇混合物的SLR过程在不同相区有不同的作用机理控制。由于甲醇的SLR弛豫速率1/T1,exp是由甲醇分子间及分子内的DD作用和SR作用三部分共同决定的,所以研究超临界和亚临界二氧化碳-甲醇混合物的SLR弛豫速率随压力、浓度及温度的变化规律有助于提供更多该混合物不同相态区分子间相互作用的动态学信息。 相似文献
19.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
20.
Evelyn Reyes-Cueva Juan Francisco Nicolalde Javier Martínez-Gmez 《Molecules (Basel, Switzerland)》2021,26(1)
Environmental problems have been associated with energy consumption and waste management. A solution is the development of renewable materials such as organic phase change materials. Characterization of new materials allows knowing their applications and simulations provide an idea of how they can developed. Consequently, this research is focused on the thermal and chemical characterization of five different avocado seed oils depending on the maturity stage of the seed: 100% unripe, 25% mature-75% unripe, 50% mature-50% unripe, 75% mature-25% unripe, and 100% mature. The characterization was performed by differential scanning calorimetry, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The best oil for natural environments corresponded to 100% matured seed with an enthalpy of fusion of 52.93 , and a degradation temperature between 241–545 °C. In addition, the FTIR analysis shows that unripe seed oil seems to contain more lipids than a mature one. Furthermore, a simulation with an isothermal box was conducted with the characterized oil with an initial temperature of −14 °C for the isothermal box, −27 °C for the PCM box, and an ambient temperature of 25 °C. The results show that without the PCM the temperature can reach −8 °C and with it is −12 °C after 7 h, proving its application as a cold thermal energy system. 相似文献