One of the amidoamine-structured hyperbranched polymers is developed as an efficient macroinitiator to enhance the endothermic capacity of hydrocarbon fuels to meet the stringent cooling requirement of hypersonic aircrafts. Hyperbranched poly(amidoamine) (PAMAM) is treated with palmitoyl chloride to modify a lipophilic shell on the hydrophilic core, and the amphiphilic product, palmitoyl-hyperbranched poly(amidoamine) (PPAMAM), can be well-dissolved in hydrocarbon fuels. The long alkyl chains in PPAMAM break away from the core at about 200 °C, and the PAMAM core destructs around 400 °C. The high decomposition temperature of the core enables PPAMAM to be performed as a macroinitiator for hydrocarbon fuels. Thermal cracking of methylcyclohexane (MCH) from 600 to 720 °C with the addition of PPAMAM is carried out in an electrically heated tubular reactor under the pressure of 3.5 MPa. Significant improvements of the conversion, gas yield, and heat sink of MCH with PPAMAM are observed. The conversion of MCH is increased from 39.5 to 56.3 wt % at 690 °C, and the corresponding heat sink has been raised from 2.48 to 2.91 MJ/kg. Furthermore, PPAMAM with the optimum molecular weight is employed for the cracking of aviation kerosene. The heat sink is also improved significantly in comparison to that from the thermal cracking of bare kerosene, which confirms the effective application of PPAMAM in endothermic hydrocarbon fuels.

Cisplatin, as a significant chemotherapeutic drug for the treatment of cancers, was combined with rapamycin (RAPA), an autophagy inducer, or 3-methyladenine (3-MA), an autophagy inhibitor, and these cisplatin combination drugs were tested with HeLa cells to explore their specific effects on autophagy by cell viability assay, mitochondria membrane potential (MMP) determination, transmission electron microscopic (TEM) observation, dansylcadaverine (MDC) staining, and western blotting analysis. Results revealed that cisplatin combination drugs enhanced formation of autophagosomes, and morphological and biochemical markers of autophagy in HeLa cells can be clearly determined with the formation of enlarged acidic vesicles and conversion of light chain 3 (LC3) protein. Cisplatin combination drugs induce stronger effects on autophagy than either of the components does. Combination drug-induced autophagy inhibits the growth of HeLa cell in a dose-dependent manner and subsequently sensitizes the cells to apoptosis and cell death. Furthermore, interactions between cisplatin combination drugs and human serum albumin (HSA) were investigated under fluorescence, synchronous fluorescence, and circular dichroism analysis. Results suggest that cisplatin combination drugs can bind to HSA and induce conformation and microenvironmental changes of HSA via electrostatic binding affinity. These investigations can provide useful and fundamental information, which could be used in cytotoxic chemotherapy to dramatically increase efficacy in pharmaceutical and biotechnology fields.

•Aggregation-dispersion of PHPG in hydrocarbons is systematically investigated.•Solubility of PHPG in fuels is enhanced dramatically by alcohols as co-surfactants.•PHPG solubilized by alcohols can further improve the heat sink of hydrocarbons.Palmitoyl-modified hyperbranched polyglycerol (PHPG), has been developed as a kind of “macroinitiator” for improving the endothermic capability of hydrocarbon fuels. As the solubilization of the macroinitiator in hydrocarbon fuels is essential to its application in practical operations, the solubility of PHPG in a series of n-alkane is evaluated theoretically via the change of Gibbs free energy in the mixing process, and is verified experimentally by the tests on the transmittance with a UV–vis spectrophotometer. The dissolution-aggregation behavior of PHPG with different molecular weights in tridecane solutions is investigated by the dynamic laser scattering (DLS) technique. n-Alcohols are applied as co-surfactants to improve the solubility of PHPG in hydrocarbon fuels. The upper critical solution temperatures (UCST) of PHPG in tridecane with the addition of alcohols are successfully lowered, and the particle sizes detected by DLS are much lower than those without alcohols. Then, the endothermic capabilities of a series of tridecane-based fuels under supercritical conditions (3.5 MPa, and 600–720 °C) are investigated in a tube reactor which is heated by a direct current. The conversion, gas yield and heat sink of each fuel in the cracking process are obtained. It is showed that the PHPG can initiate the cracking of hydrocarbon fuels and enhance their endothermic capability significantly. With the addition of alcohols, not only the solubility of PHPG in hydrocarbon fuels is improved significantly, but also the heat sink of hydrocarbons is further raised to a higher value.Download high-res image (190KB)Download full-size image

•A fluorescent protein-based biosensor that genetically incorporates a metal ion binding site was produced.•The protein biosensor showed a selective fluorescence enhancement in the presence of Al3+ at the μΜ level.•In vivo tests were carried out to demonstrate the detection performance in practical situations.A protein-based fluorescent sensor for the efficient detection of Al3+ is reported. The sensor is genetically engineered through the residue-specific incorporation of 3, 4-dihydroxy-l-phenylalanine (Dopa) into a green fluorescent protein (GFP) (termed as GFP-Dopa) and can selectively detect Al3+ in aqueous media. Al3+ could be readily detected through the distinctive fluorescence enhancement as a result of strong chelation of Al3+ with GFP-Dopa. Among 15 different tested metal ions, only Al3+ induces a significant fluorescence enhancement of GFP-Dopa, suggesting a high selectivity and exclusive specificity of GFP-Dopa towards Al3+. Together with its high biocompatibility, this protein-based sensor could be used in various applications requiring the rapid and sensitive detection of Al3+.Download high-res image (107KB)Download full-size image

•HPG/PAA hydrogels show the sensitivity to the change of ionic strength of aqueous solution.•Immobilized enzyme was released from the hydrogel by regulating the ionic strength of aqueous solution.•Biodiesel yield of immobilized enzyme remain over 90% after five consecutive uses.•Response surface methodology was employed to optimize the synthesis parameters.Hyperbranched polyglycerol and acrylic acid were polymerized into smart hydrogel for enzyme immobilization. Lipase from Aspergillus oryzae was selected as model enzyme. Highest enzyme loading amount of 78.93 mg/g and relative enzyme activity of 67.02% were observed. The immobilized enzyme was further used for the synthesis of biodiesel, and the synthesis parameters were optimized with response surface methodology. The yield of fat acid methyl esters (FAMES) under the optimum synthesis condition was determined to be 95.98%. The immobilized enzyme showed good reusability for five consecutive operations without significant loss of FAMES yield. By means of regulating the ionic strength of aqueous solution, the immobilized enzyme was successfully released from the hydrogel. After the enzyme reload, FAMES yield of fresh immobilized enzyme still remained 90% approximately for five consecutive operations. The results demonstrated that the hyperbranched polyglycerol/polyacrylic acid hydrogels could be effectively applied to the enzyme carrier and biodiesel synthesis.

•Safe run time (SRT) is used to evaluate the heat transfer security of each fuel.•The tested fuels are laboratory modified aviation kerosene for aircraft.•The performance of Fuel 1(0.85 g/cm3) is better than that of Fuel 2(0.78 g/cm3).•Modifying high density fuel with additive is a valid way to prepare an advanced fuel.Jet fuel is used as a coolant before it is burned in the combustor of the aircraft. Insoluble particles and surface deposits can impair engine performance. Jet fuel thermal oxidation test (JFTOT) defines the standard test method for evaluation of the deposit formed through heating fuels in tubes caused by thermal oxidation (< 400 °C). At a higher temperature, fuel in the heating process decomposes leading to surface deposits by coking. In this work, we propose a method to evaluate the security of fuel flowing in the tube at high temperatures (> 500 °C). The heat transfer and cracking performances of two hydrocarbon fuels which are laboratory modified aviation kerosene (Fuel 1 (ρ = 0.85 g/cm3) and Fuel 2 (ρ = 0.78 g/cm3)) have been investigated in a heat-exchanger under supercritical conditions (T = 700–770 °C, p = 2.5–5.5 MPa, m = 0.4–1.0 g/s). The temperature and flow rate in this work are much higher than those in JFTOT. The safe run time (SRT) is used to evaluate the heat transfer security of each fuel. As the temperature increases or the flow rate decreases or the pressure increases, the SRTs of Fuel 1 and Fuel 2 decrease clearly. In general, the heat transfer security of Fuel 1 is better than that of Fuel 2. Moreover, the volumetric heat sink of Fuel 1 is larger than that of Fuel 2. So, the overall performance of Fuel 1 is more excellent when it is used as propellant and coolant for hypersonic aircraft. In consideration of the heat transfer security, heat sink and the required driving force for aircraft, the temperature of fuel at the exit of heat transfer passage should be set as 740 °C, the flow rate of fuel should be 0.6–1.0 g/s, the pressure of heat transfer passage should be 3.5 MPa. Based on these results, we find that the modification of a high density fuel is an effective way to prepare an advanced hydrocarbon fuel.

Although shape and size controllable palladium nanocrystals have attracted enormous attention, the growth behavior of Pd nanocubes is not thoroughly understood. In this work, the growth pattern of size controllable Pd nanocubes is studied systematically under a variety of reaction conditions. During the growth process of the Pd nanocubes, various structures including concave cubes, triangular bipyramids, pentagonal bipyramids (decahedrons) and pentagonal rods can be generated due to the disparate behavior of the fresh Pd atoms. Different-sized nanocubes are prepared controllably by changing the dosage of KBr, which provides capping capacities toward the {100} facets that the cubes are enclosed with. Both ascorbic acid (AA) and KBr influence the reducing rate of the Pd precursors and the growth kinetics of the nanocrystals, and furthermore control the morphologies of the products. This detailed research supplements the understanding of crystal growth, and provides insight toward the comprehension of atom movements at the nanoscale.

To break oil-in-water emulsions with an average oil droplet size of <2 μm, a series of hyperbranched polyglycerol (HPG)-based demulsifiers—methacrylated hyperbranched polyglycerol (HPG-MA)—are synthesized successfully by controlling the ratio of HPG to glycidyl methacrylate (GMA). Dosage, temperature, settling time, and salinity are taken into account to evaluate the performance of these demulsifiers, respectively. The oil removal ratio with the addition of HPG-MA demulsifier can exceed 86% within 40 min to reach the equilibrium of demulsification, in comparison with ∼90 min for previously reported demulsifiers. Because of the specific branched structure, the demulsifier can multipointly adhere to the oil/water interface, and then shorten the time of adsorption and increase the rupture rate of oil droplets. The oil–water interfacial tensions with the demulsifier in the water phase are further measured to help comprehend the demulsification mechanism. The change of oil droplet size against time, which reflects flocculation and coalescence of oil droplets, is vividly monitored during the process of demulsification. The demulsification performance indicates that the novel HPG-MA demulsifier displays great promise in the petroleum industry.

The ionic liquid (IL), 2,2-diethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([(C2)22(C1)2(C1)23gu][C2OSO3]), was synthesized and characterized. The density and viscosity data were determined for the binary mixtures of [(C2)22(C1)2(C1)23gu][C2OSO3] with water, methanol, or ethanol over the whole concentration range at different temperatures T = 293.15–323.15 K and atmospheric pressure p = 0.1 MPa. The excess molar volume, VmE, and viscosity deviation, Δη, for the binary mixtures are calculated and fitted with the Redlich–Kister type polynomial equation. The values of VmE for [(C2)22(C1)2(C1)23gu][C2OSO3] + water system are observed to be negative, and those for [(C2)22(C1)2(C1)23gu][C2OSO3] + methanol/ethanol system change from negative to positive against the mole fraction (x1) of the IL, which exhibit the minimum values around x1 = 0.2 and the maximum values near x1 = 0.8. The Δη values for all of the three binary systems are negative, and the minimum values occur near x1 = 0.6. The temperature dependence of viscosity for pure [(C2)22(C1)2(C1)23gu][C2OSO3] and its binary mixtures can be well correlated with the Vogel–Fucher–Tammann equation. These fundamental physicochemical properties of the binary mixtures make for a better comprehension of the guanidinium-based ILs and the potential applications.

•iso-Octane can accelerate the thermal decomposition of JP-10.•Inhibition–initiation is present in the cracking of JP-10/iso-octane mixture.•The density functional theory is used to explain the formation of product.To mainly investigate the initiation effect of iso-octane as an activation component on the binary model fuels of JP-10/iso-octane, the thermal decomposition of JP-10, iso-octane and their mixtures has been performed in a stainless-steel tubular reactor at the temperatures from 883 K to 963 K. The conversions of components, and the yields of gas and liquid products for each sample are determined in detail. The addition of iso-octane can promote the decomposition of JP-10, and the initiation (of JP-10)-inhibition (of iso-octane) effects can be observed during the decomposition processes of JP-10/iso-octane mixtures. One possible mechanism has been proposed to demonstrate the initiation effect of iso-octane on the decomposition of JP-10. For the possible pathways, the rate constants of the H-abstraction reactions between the alkyl radicals obtained from CC bond fission of iso-octane and the H atoms of JP-10 are calculated from the density functional theory (DFT). In combination with the quantum calculations and experimental observations, the formation of some decomposition products in the JP-10/iso-octane mixtures can be reasonably illustrated.

•Volumetric property of four amino acids in aqueous solutions of [Phpi][BF4] were measured.•The standard partial molar volume, transparent partial molar volume and hydration number were calculated.•[Phpi][BF4] interacts strongly with four kinds of amino acids.•Hydrophilic–hydrophobic and hydrophobic–hydrophobic interactions play the dominant roles in ternary systems.•The ternary systems are generated via multiple hydrogen bond interactions.The densities of aqueous solutions of glycine, l-serine, l-alanine, l-proline with the ionic liquid (IL), 1-phenylpiperazinium tetrafluoroborate ([Phpi][BF4]) at the IL concentrations of (0.025, 0.055 and 0.100) mol·kg−1 have been measured at the temperatures of (298.15, 303.15 and 308.15) K. On the basis of the experimental results, the apparent molar volume (VФ), standard partial molar volume (VФ0), transfer partial molar volume (ΔtrVΦ0) and hydration number (nH) have been calculated. The hydrophilic–hydrophilic, hydrophobic–hydrophilic and hydrophobic–hydrophobic interactions are involved in the studied systems of {[Phpi][BF4] + amino acids + H2O. These volumetric parameters can help to understand the mixing effects and other complex biological processes between amino acids and ionic liquid aqueous solution.

•Interactions of human serum albumin (HSA) with eight quaternary ammonium surfactants are investigated by various measurements.•Complexes with larger size can be detected in gemini surfactant-HSA systems than in single-chain surfactant-HSA systems.•Gemini surfactants have much strong binding ability to induce the unfolding of HSA in comparison with the single-chain surfactants.The interactions of human serum albumin (HSA) with four cationic gemini surfactants and four single-chain surfactants have been investigated from the measurements of fluorescence spectroscopy, dynamic lights scattering (DLS), zeta potential, and circular dichroism (CD). The fluorescence results show the binding strength of surfactants to HSA, along with the blue shift under the maximum emission wavelength (λmax) which is sensitive to the protein conformations. It has been found that the hydrodynamic diameters of the protein aggregates are enlarged and the electrokinetic potentials of them get positive with increasing the concentration of the surfactants. The conformational transformation of the secondary structures of surfactant–HSA aggregates has been confirmed through the quantitative analysis of the CD spectra. The isothermal titration microcalorimetry (ITC) has been employed to further analyze the binding process of single-chain surfactants to HSA. The comprehensive results obtained from various approaches have shown that both hydrophobic and electrostatic interactions are present in the cationic surfactant–HSA systems. Compared with the corresponding single-chain surfactants, the gemini ones have much stronger binding ability to induce the unfolding of HSA. These investigations on the interactions between HSA and surfactants with the altered chain architecture in different concentration regimes can facilitate the application of surfactant-protein systems in pharmaceutical, biotechnology and related fields.

•Fractal surfaces were prepared by the solid–solid phase transformation method.•C6 cells were cultured on the PPP surface which imitate the fractal environment.•Hydrophobic surfaces have significant effects on cell proliferation and morphology.To provide a biomimic environment for glial cell culture, glycerol tripalmitate (PPP) has been used as a raw material to prepare fractal surfaces with different degrees of hydrophobicity. The spontaneous formation of the hydrophobic fractal surfaces was monitored by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The surface morphologies were observed by a scanning electron microscope (SEM), and then the fractal dimension (FD) values of the surfaces were determined with the box-counting method. C6 glioma cells were cultured and compared on different hydrophobic PPP surfaces and poly-L-lysine (PLL)-coated surface. The cell numbers as a function of incubation time on different surfaces during the cell proliferation process were measured, and the cell morphologies were observed under a fluorescence microscope. Influences of hydrophobic fractal surfaces on the cell number and morphology were analyzed. The experimental results show that the cell proliferation rates decrease while the cell morphology complexities increase with the growth of the fractal dimensions of the PPP surfaces.

Two novel aqueous two-phase systems (ATPSs) involving protic piperazinium-based ionic liquids (ILs) and anionic surfactants were found in the 1-ethylpiperazinium tetrafluoroborate ([C2pi][BF4]) + sodium dodecyl sulfate (SDS) + H2O system and the 1-phenylpiperazinium tetrafluoroborate ([Phpi][BF4]) + sodium dodecyl benzenesulfonate (SDBS) + H2O system. The ATPS regions in the ternary phase diagrams were determined, and the compositions and the microstructures of the conjugated phases were analyzed by UV–vis, 1H NMR, DLS, and cryogenic TEM measurements. The results demonstrate size-enhanced micelles for both ATPSs. The strong electrostatic interactions between the cationic moiety of IL and the anionic surfactant play a very important role in the assembly of the large aggregates, and the cation−π interactions are involved in the [Phpi][BF4] + SDBS + H2O ATPS. In addition, the small cationic moiety of [C2pi][BF4] can be packed in the micelles, while the larger hydrophilic cationic moiety of [Phpi][BF4] makes it difficult to get into the micelles, leading to the different size enhancement effects. The driving force of phase separation is the formation and distribution of the large aggregates in the aqueous solutions. This work presents a novel nonaromatic ATPS formed by a piperazinium-based IL and an anionic surfactant, in which considerable size enhancement of aggregates takes place without the assistance of aromaticity in contrast to the other aromatic ATPSs.

The application of ionic liquids (ILs) for acidic gas absorption has long been an interesting and challenging issue. In this work, the ethyl sulfate ([C2OSO3]−) anion has been introduced into the structure of guanidinium-based ILs to form two novel low-cost ethyl sulfate ILs, namely 2-ethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([C22(C1)2(C1)23gu][C2OSO3]) and 2,2-diethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([(C2)22(C1)2(C1)23gu][C2OSO3]). The ethyl sulfate ILs, together with 2-ethyl-1,1,3,3-tetramethylguanidinium bis(trifluoromethylsulfonyl)imide ([C22(C1)2(C1)23gu][NTf2]) and 2,2-diethyl-1,1,3,3-tetramethylguanidinium bis(trifluoromethylsulfonyl)imide ([(C2)22(C1)2(C1)23gu][NTf2]), are employed to evaluate the SO2 absorption and desorption performance. The recyclable ethyl sulfate ILs demonstrate high absorption capacities of SO2. At a low pressure of 0.1 bar and at 20 °C, 0.71 and 1.08 mol SO2 per mole of IL can be captured by [C22(C1)2(C1)23gu][C2OSO3] and [(C2)22(C1)2(C1)23gu][C2OSO3], respectively. The absorption enthalpy for SO2 absorption with [C22(C1)2(C1)23gu][C2OSO3] and [(C2)22(C1)2(C1)23gu][C2OSO3] are −3.98 and −3.43 kcal mol–1, respectively. While those by [C22(C1)2(C1)23gu][NTf2] and [(C2)22(C1)2(C1)23gu][NTf2] turn out to be only 0.17 and 0.24 mol SO2 per mole of IL under the same conditions. It can be concluded that the guanidinium ethyl sulfate ILs show good performance for SO2 capture. Quantum chemistry calculations reveal nonbonded weak interactions between the ILs and SO2. The anionic moieties of the ILs play an important role in SO2 capture on the basis of the consistently experimental and computational results.

Two guanidinium-based ionic liquids (ILs), 2-ethyl-1,1,3,3-tetramethylguanidinium bis(trifluoromethylsulfonyl)imide ([TMGEt][NTf2]) and ethyl sulfate ([TMGEt][C2OSO3]) were synthesized and characterized. Experimental densities and viscosities for the binary mixtures of the ILs with ethanol and 1-propanol from (293.15 to 323.15) K were measured over the whole composition range and at the atmospheric pressure of 0.1 MPa. The excess molar volumes (VmE) and the viscosity deviations (Δη) for the binary systems were calculated and fitted with the Redlich–Kister equation. It is found that the density of [TMGEt][NTf2] is much higher than that of [TMGEt][C2OSO3] at the same temperature, while the viscosity of the former with the value of 74.61 mPa·s is only 1/9 of that of the latter at 293.15 K. This indicates that the difference of the anions has a significant influence on the density and viscosity of the ILs with the same guanidinium cation. The addition of ethanol or 1-propanol leads to negative values of VmE and Δη, which result from the efficient packing of the constituents in the binary mixtures and the weakening of anion–cation interactions of the ILs. The partial molar volumes, excess partial molar volumes, Gibbs energy, and excess Gibbs energy of activation for viscous flow of the binary mixtures also have been calculated. It is hoped that the results provide useful information for the fundamental physicochemical properties of the guanidinium-based ILs and their further applications.

Twelve gemini quaternary ammonium surfactants have been employed to evaluate the antibacterial activity and in vitro cytotoxicity. The antibacterial effects of the gemini surfactants are performed on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with minimum inhibitory concentrations (MIC) ranging from 2.8 to 167.7 μM. Scanning electron microscopy (SEM) analysis results show that these surfactants interact with the bacterial cell membrane, disrupt the integrity of the membrane, and consequently kill the bacteria. The data recorded on C6 glioma and HEK293 human kidney cell lines using an MTT assay exhibit low half inhibitory concentrations (IC50). The influences of the gemini surfactants on the cell morphology, the cell migration ability, and the cell cycle are observed through hematoxylin-eosin (HE) staining, cell wound healing assay, and flow cytometric analyses, respectively. Both the values of MIC and IC50 decrease against the growth of the alkyl chain length of the gemini surfactants with the same spacer group. In the case of surfactants 12-s-12, the MICs and IC50s are found to decrease slightly with the spacer chain length changing from 2 to 8 and again to increase at higher spacer length (s = 10–12). All of the gemini surfactants show great antibacterial activity and cytotoxicity, and they might exhibit potential applications in medical fields.

The densities, viscosities, and electrical conductivities of the binary systems of the ionic liquid (IL), N-(2-hydroxyethyl)piperazinium propionate ([(OH)2C2pi][C2CO2]), with three protic solvents (water, methanol, or ethanol) were measured in the IL concentration range from (0.05 to 3.00) mol·kg–1 at different temperatures T = (293.15 to 323.15) K and atmospheric pressure p = 0.1 MPa. The concentration dependences of apparent molar volume, viscosity, and electrical conductivity of the binary mixtures were correlated by the Pitzer equation, the Jones–Dole equation, and the Casteel–Amis equation, respectively. It is observed that both the density and viscosity increase with the elevated IL concentration or the decreased temperature. The electrical conductivity at a given IL concentration increases with the temperature, while the conductivity at a given temperature changes clearly against the IL concentration, and a maximum value can be observed. The measured results and the correlations present help for a better understanding and applications of the piperazinium-based IL.

Three kinds of piperazinium-based room-temperature ionic liquids (RTILs), namely, N-methylpiperazinium lactate ([C1pi][Lac]), N-ethylpiperazinium lactate ([C2pi][Lac]), and N,N′-dimethylpiperazinium dilactate ([C1C1pi][Lac]2), have been synthesized by the direct reaction of N-alkyl-substituted piperazines and lactate acid. Together with 1,1,3,3-tetramethylguanidinium lactate ([TMG][Lac]), they are employed as new extractants for removing aromatic sulfur compounds, thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT), and 4-methyldibenzothiophene (4-MDBT), from various hydrocarbon fuels. The effects of the temperature, extraction time, and amount of ionic liquid (IL) on the sulfur removal are investigated systematically. The mutual solubility measurements show that the ILs are dissolved in n-heptane with the mass fraction less than 0.01 at 30 °C. The solubility values of 93 gasoline in the ILs are observed with the following sequence: [C1C1pi][Lac]2 (0.007 in mass fraction) < [C1pi][Lac] (0.014 in mass fraction) < [TMG][Lac] (0.017 in mass fraction) < [C2pi][Lac] (0.070 in mass fraction), and the sulfur distribution coefficient follows the order: [TMG][Lac] (1.08 in mass fraction) > [C2pi][Lac] (0.98 in mass fraction) > [C1pi][Lac] (0.78 in mass fraction) > [C1C1pi][Lac]2 (0.53 in mass fraction) for 93 gasoline. Selectivity between TS and toluene is observed higher than 4 with the following sequence: [TMG][Lac] (13.19 in mass fraction) > [C1pi][Lac] (10.59 in mass fraction) > [C2pi][Lac] (7.12 in mass fraction) > [C1C1pi][Lac]2 (4.94 in mass fraction), revealing that these ILs are more preferable to extract TS than toluene from hydrocarbon fuels. The used ILs can be recycled without a significant decrease of desulfurization activity after extraction 5 times. These fundamental results hopefully provide useful information for future commercialization and practical desulfurization.

Thermal decomposition of 1,1′-bicyclohexyl, a potential surrogate component of high-density hydrocarbon fuels, was performed in a batch-type reactor to investigate its thermal stability. A first-order kinetic equation is supposed to correlate the decomposition process, and the apparent rate constants, ranging from 0.0223 h–1 at 683 K to 0.1979 h–1 at 713 K, are determined. The Arrhenius parameters are determined with the pre-exponential factor A = 6.22 × 1020 h–1 and the activation energy Ea = 293 kJ·mol–1. Compared with four typical hydrocarbon compounds, the thermal stability trend is observed in the order of n-dodecane ≈ 1,3,5-triisopropylcyclohexane > bicyclohexyl > n-propylcyclohexane > decalin. Cyclohexane and cyclohexene are found to be the primary products due to the relatively low energy of the C–C bond connecting the two cyclohexyl rings. Bicyclohexyl decomposes into cyclohexane and cyclohexene equivalently at the beginning of the reaction. A probable mechanism on the basis of quantum calculation and GC-MS analyses for the decomposition of bicyclohexyl is proposed to explain the product distribution. It is shown that the formation of decomposition products is mainly obtained through hydrogen transfer, β-scission, isomerization, or dehydrogenation.

For a comprehensive understanding of the properties of 1,3-dimethyladamantane (1,3-DMA) as a candidate of high energy-density hydrocarbon fuels, thermal stability of 1,3-DMA under different conditions is investigated. The thermal decomposition kinetics in the batch reactor between 693 and 743 K has been determined, with the rate constants ranging from 4.00 × 10–7 s–1 at 693 K to 35.19 × 10–7 s–1 at 743 K, along with the Arrhenius parameters of A = 2.39 × 107 s–1 and activation energy Ea = 183 kJ·mol–1. The rate constants for the thermal decomposition of 1,3-DMA are observed to be smaller than those of some typical model fuels, decalin, propylcyclohexane, butylcylohexane, and n-dodecane, demonstrating that the thermal stability of 1,3-DMA is satisfactory. The thermal decomposition of 1,3-DMA in the flowing reactor at temperatures from 873 to 973 K and pressures from 0.1 to 5.0 MPa is further performed. It can be observed that the conversion of 1,3-DMA and the yield of gaseous products increase clearly with the rise of temperature or pressure. The residence time is the main factor for the change of decomposition depth. Methane and hydrogen are the major gaseous products that are produced through demethylation and dehydrogenation. In the liquid residues, toluene and xylene are observed and quantified by GC-MS, HPLC, and NMR as the main aromatics produced. On the basis of component analysis, a hypothetical mechanism of thermal decomposition of 1,3-DMA is proposed to explain the product distribution. It is shown that the different products are mainly obtained through a combination of isomerization, hydrogen transfer, β-scission, and dehydrogenation. The results are expected to provide experimental information for the search of new high energy-density hydrocarbon fuels.

Interfacial tensions of the oil–water interface versus surfactant concentration for n-heptane + water system with each of six single chain quaternary ammonium surfactants, and six Gemini quaternary ammonium surfactants around their critical micelle concentrations (CMC) have been measured by using the spinning drop method. The influences of additives (NaCl, ethanol, n-propanol, and n-butanol) on the interfacial tensions have also been investigated. It is observed that all of the surfactants can significantly lower the interfacial tensions of the n-heptane + water system. The required concentrations to reach the lowest interfacial tensions for Gemini surfactants with C12 and C14 alkyl chains are less than 10 % of those values for the corresponding single chain surfactants. For the n-heptane + water + Gemini surfactant systems, the addition of NaCl can lower the required surfactant concentrations to obtain the lowest interfacial tensions; however, the addition of C2–C4 alcohols has no evident effects but leads to a slight decrease of the values of these interfacial tensions.

For a comprehensive understanding of the properties of 1,3-dimethyladamantane (1,3-DMA) as a new potential candidate of high energy-density hydrocarbon fuels, densities, viscosities, surface tensions, and refractive indices for binary mixtures of 1,3-DMA with each of four C10 alkanes, n-decane, butylcyclohexane, decalin, and exo-tetrahydrodicyclopentadiene (JP-10), are determined over the whole composition range at different temperatures ranging from (293.15 to 363.15) K and atmospheric pressure (0.1 MPa). The excess molar volume (VmE), the viscosity deviation (Δη), the surface tension deviation (Δγ), and the refractive index deviation (ΔnD) for these binary systems are calculated. All of the VmE values are negative over the whole composition range for these systems, and they show slight changes against the temperature. The Δη values for the systems except 1,3-DMA + JP-10 are negative, and the absolute values decrease obviously with rising temperature. The Δγ gives clearly negative values for the system of 1,3-DMA + n-decane and shows small values near zero for the other systems. Negligible values of ΔnD indicate that the refractive indices show nearly linear additions from those of two components for the binary mixtures. The results could provide important reference information for the development and performance of new high energy-density hydrocarbon fuels.

Measurements on densities (ρ), viscosities (η), and refractive indices (nD) from (293.15 to 333.15) K and at 0.1 MPa along with the surface tensions (γ) at 298.15 K and 0.1 MPa for binary mixtures of 1,3-dimethyladamantane (1,3-DMA), 1-ethyladamantane (1-EA), and 1,3,5-trimethyladamantane (1,3,5-TMA) with 1-heptanol or cyclohexylmethanol have been carried out over the entire composition range. The experimental data are used to calculate the excess molar volumes (VmE), viscosity deviations (Δη), molar refraction deviations (ΔΦR), and surface tension deviations (Δγ). The VmE, Δη, ΔΦR, and Δγ values have been fitted to the Redlich–Kister polynomial equation. From these excess or deviation functions, the molecular interactions and nonideality of the binary systems are discussed. The results are expected to provide fundamental data for understanding the properties of adamantane derivatives as potential components and the composition optimization of new high energy-density hydrocarbon fuels.

Investigation of conformational isomerism of ring compounds can help us get a clear comprehension of the ring structure and reveal significant structure–activity relationship. In this study, conformational isomerism of the cationic moiety of ionic liquid 1-ethyl-1,4-dimethylpiperazinium bis(trifluoromethylsulfonyl)imide ([C2C1C14pi][NTf2]) has been investigated by means of 1H nuclear magnetic resonance spectra. The energy levels for different conformations of the cationic moiety [C2C1C14pi]+ are obtained via density functional theory calculations. The predominant cis-conformer in [C2C1C14pi][NTf2] at its liquid state is observed under ambient conditions, where the ethyl group locates at the equatorial position of quaternary nitrogen atom, consistent with the calculated results. The trans-conformer minorities in the IL convert to the cis-conformers when [C2C1C14pi][NTf2] is well crystallized. Besides, the addition of polar solvents, such as ethanol, leads to a convenient and complete transformation from the trans-form to the recognizable cis-form. The phase-transition behaviors have been measured by means of differential scanning microcalorimetry (DSC), and the DSC results can be highly affected by the initial state of the IL. Density and viscosity measurements for mixtures of [C2C1C14pi][NTf2] with ethanol or 1-propanol at different temperatures T = (293.15 to 323.15) K are performed. Conformational isomerism affects the excess molar volumes of [C2C1C14pi][NTf2] + alcohol systems more significantly than the viscometric property. The behaviors, as comparison, for the mixtures of 1-n-pentyl-1,4-dimethyl-piperazinium bis(trifluoromethylsulfonyl)imide ([C5C1C14pi][NTf2]) with ethanol are observed with the same phenomena as the common binary systems. On the basis of the experimental and calculated results of the ILs, it can be concluded that conformational isomerism in the cation of [C2C1C14pi][NTf2] is quite significant, and it should be taken into account when sensitive properties are evaluated.

The micellization of six Gemini quaternary ammonium surfactants aqueous solutions has been investigated from measurements on specific conductivity as a function of surfactant concentration at different temperatures from (298.15 to 323.15) K. The micellization parameters such as the critical micellar concentration (CMC) and the degree of counterion dissociation (β), Gibbs free energy (ΔGmic), enthalpy (ΔHmic), and entropy (ΔSmic) of micellization are then obtained. It is shown that the conductometry measurements provide agreement of the CMC values at 298.15 K with the surface tension studies. With the rise of temperature, the values of CMC and β increase, while ΔGmic changes little. The linear plots of TΔSmic versus ΔHmic show the effects of enthalpy–entropy compensation. The length of alkyl chain and the spacer group of the Gemini surfactant have significant influences on micellization parameters.

•Surface-modified Pd nanoparticles were synthesized with diameters of 1–3 nm.•Nanofluids were prepared with Pd NPs and decalin/kerosene.•An electrically heated apparatus for cracking of fuel-based nanofluids was built.•Heat sink was enhanced for cracking of decalin/kerosene prepared as a nanofluid.Three different kinds of palladium nanoparticles modified by octadecanethiol, octadecylamine, and mixture of them have been prepared, which are simply marked as Pd@S, Pd@N and Pd@S&N in turn. The nanoparticles are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermo-gravimetric analysis (TGA). It follows that the average diameters of the nanoparticles are 1–3 nm. Pd@S shows noncrystalline structure, while Pd@N and Pd@S&N show face-center cubic (fcc) structure. These palladium nanoparticles can be well-dispersed in decalin, and then the nanofluids composed of decalin and palladium nanoparticles are prepared, which can be regarded as pseudohomogeneous systems. The cracking of each nanofluid containing 500 ppm Pd is performed under supercritical conditions (3.5 MPa, 600–750 °C) of decalin with a mass flow rate of 1 g/s in an electrically heated tube reactor which simulates a single passage in a practical heat exchanger. The cracking results indicate that these nanoparticles exhibit catalytic activity to a certain extent, and the activity of Pd@N nanoparticles is better than that of Pd@S or Pd@S&N. At 750 °C, the conversion of decalin is raised from 70.31 wt% of thermal cracking to 73.21 wt% with the existence of Pd@S, while that raised to 80.54 wt% with Pd@S&N and even raised to 91.85 wt% with Pd@N. The heat sink of nanofluids is effectively enhanced, and the nanofluid containing Pd@N shows the highest value, which reaches 3.50 MJ/kg and is increased by 0.29 MJ/kg in comparison with the heat sink of thermal cracking at 750 °C. The cracking of aviation kerosene containing Pd nanoparticles is then performed, the results of which confirm the feasibility of practical application of Pd nanoparticles to hydrocarbon fuels.

•Thermal stability of two n-alkanes is evaluated by monitoring the produced aromatics.•Amounts of aromatics are compared by NMR, HPLC and GC/MS analyses.•Kinetics on the n-alkanes under thermal cracking are presented.The thermal stability of n-nonane and n-undecane, as the model endothermic hydrocarbon fuels, was evaluated by determining the content change of produced aromatics during the thermal cracking process. The 1H nuclear magnetic resonance spectroscopy (1H NMR), along with the high-performance liquid chromatography (HPLC) and the gas chromatography/mass spectrometry (GC/MS) analyses, is mainly considered to follow the formation of aromatics in the liquid cracking residues of the n-alkanes. The results of the aromatic contents obtained from these three analytical methods show satisfactory agreements. The 1H NMR method also gives the olefin content and the branching index of the liquid residues. The changes of the aromatics, olefins and branching index against the temperature directly reflect the thermal stability of the n-alkanes. Based on the results from 1H NMR, HPLC and GC/MS, a scheme of the formation of aromatics from the thermal cracking of n-alkanes is discussed.

With surfactants, butanediyl-1,4-bis(dimethylcetyl ammonium bromide) (16–4–16), and N,N-dimethylhexadecylamine (C16DMA), as the stabilizers and surface-modified reagents, stable oil-based nanofluids containing hydrophobic gold nanoparticles have been prepared. The gemini surfactant 16–4–16 shows better performance than C16DMA for controlling the growth of gold particles. The gold nanoparticles modified by 16–4–16 are dispersed well in oil-based fluids. The nanofluids can be treated as pseudohomogeneous catalyst systems. The viscosities at different temperatures of the nanofluids containing the surface-modified gold nanoparticles with the gemini surfactant 16–4–16 are measured. Catalytic cracking of tricycle [5.2.1.02.6] decane (JP-10) with surface-modified gold nanoparticles as the catalyst has been investigated. The catalytic cracking exhibits clearly enhanced conversion in comparison with the thermal cracking.

Densities, viscosities, and refractive indices have been measured for the binary system of tricyclo[5.2.1.02.6]decane with cyclohexane, methylcyclohexane, ethylcyclohexane, butylcyclohexane, or 1,2,4-trimethylcyclohexane at temperatures T = (293.15 to 318.15 K) and pressure p = 0.1 MPa. The excess molar volumes (VmE), the viscosity deviations (Δη), and the refractive index deviations (ΔnD) are then calculated. The changes of VmE and Δη with the composition are fitted to the Redlich–Kister equation. The values of density, viscosity, and refractive index increase continuously with the increase of mole fraction of tricyclo[5.2.1.02.6]decane and decrease with the rise of temperature. The VmE and Δη are all negative over the whole composition range for these five binary systems. The changes of VmE and Δη are discussed from the points of view of molecular interactions in the binary systems.

•Temperature-induced phase inversion phenomena are observed.•Difference of density change rate is the direct reason for phase inversion.•Property differences are lowest around the phase-inversion temperature.•Transfers of ions make main contributions to the change of density difference.•Microstructures in the separated phases change along the temperature.Three quaternary ammonium surfactants, N-alkyl-N, N-2-dihydroxyethyl-N-methyl ammonium bromide (CnDHAB, n = 12, 14, and 16) and sodium dodecyl sulfate (SDS) have been used to form aqueous two-phase systems of cationic–anionic surfactant mixtures with cationic surfactant in excess (ATPS-C). Densities, viscosities, interfacial tensions and ion concentrations of/between the two separate phases were measured and microstructures were observed as a function of temperature to elucidate the temperature effect on ATPS-C and the phase inversion. The density of the surfactant-concentrated phase decreases against the temperature faster than that of the dilute phase, which can lead to the phase inversion at a certain temperature. The ultralow interfacial tension between the separated phases can be determined, which exhibits a minimum near the phase inversion temperature. It is followed that the property differences between the separated phases are the lowest around the phase-inversion temperature. Composition analyses manifest that the inorganic ions transferring from the concentrated phase to the dilute phase with increasing the temperature. These transformations make main contributions to the change of density difference between the separate phases. Combining the results of viscosity measurement, dynamic light scattering (DLS), and transmission electron microscopy (TEM), it is evident that network structures and large aggregates are destroyed and smaller spherical micelles or vesicles can be observed in the concentrated phase with increasing the temperature. In the dilute phase, vesicles can be observed and most of the aggregates are irregular micelles especially at lower temperatures before the phase inversion occurs.Phase inversion of C12DHAB/SDS/NaCl system (CT = 8.000 × 10−2 mol L−1, MRC12DHAB/SDS=1.963,MRC12DHAB/SDS=1.963,CNaCl = 6.000 × 10−2 mol L−1) with crystal violet as dye during the heating process. (A) 42.0 °C; (B) 45.5 °C; (C) 46.5 °C; (D) 47.5 °C; (E) 51.0 °C.

Based on the measurements of conductivity and surface tension and our previously reported results of isothermal titration calorimetry (ITC), the surface activity and micellization parameters, such as the critical micellar concentration (CMC), the degree of counterion dissociation (β), and thermodynamic functions of micellization, for six quaternary ammonium surfactants, dodecyl-(2-hydroxyethyl)-dimethylazanium bromide, tetradecyl-(2-hydroxyethyl)-dimethylazanium bromide, hexadecyl-(2-hydroxyethyl)-dimethylazanium bromide, dodecyl-di(2-hydroxyethyl)-methylazanium bromide, tetradecyl-di(2-hydroxyethyl)-methylazanium bromide, and hexadecyl-di(2-hydroxyethyl)-methylazanium bromide in aqueous solutions have been investigated. The values of CMC determined from three different methods are compared, and they show reasonable agreement. From the CMC values obtained from the conductivity measurements in this work and the previously reported values of calorimetric enthalpy of micellization, the Gibbs free energy (ΔGmic) and entropy (ΔSmic) of micellization are calculated through the mass-action model. The influences on the micellization parameters of the temperature, the length of alkane chain, and the number of hydroxyethyl substituents on the surfactant headgroup are discussed.

Density, viscosity, flash point and refractive index for binary mixtures of cis-decalin or trans-decalin with nonane, decane, and undecane have been determined at pressure p = 0.1 MPa and different temperatures ranging from (293.15 to 323.15) K. The calculated excess molar volumes give negative values over the whole composition range for these binary systems. With the increase of mole fraction of decalin, the values of viscosity and refractive index increase continuously. The viscosity deviation and refractive index deviation are calculated, showing negative from the corresponding linear additive values. A small additional amount of the component with lower flash point leads to marked changes of flash point values of these binary mixtures.

A total of 10 new N-alkyl piperazinium-based ionic liquids (ILs) have been prepared, and they are used as extractants for removing aromatics from three kinds of hydrocarbon fuels. A total of 3 ILs, N-methyl piperazinium lactate (MPL), N-ethyl piperazinium lactate (EPL), and N-ethyl piperazinium propionate (EPP), in the liquid state at room temperature are used directly for extraction, while the other 7 ILs in the solid state at room temperature are used with methanol as the co-solvent. Effects on the extraction efficiency of the temperature and the amounts of IL and co-solvent are investigated. The results indicate that the amounts of IL and co-solvent play very important roles in the extraction process and the efficiency is greatly influenced by the cation and anion structures in the N-alkyl piperazinium-based ILs. In comparison to 1,1,3,3-tetramethylguanidinium lactate (TMGL), the extraction capability order is EPP > EPL > MPL > TMGL. The ILs with aromatic anions are found to have better extraction capability than the others. Furthermore, recycling of ILs reflects that these ILs can be recovered simply by vacuum distillation without a significant decrease in the activity of dearomatization.

Triglyceride surfaces were prepared by solidification from the melting of binary mixtures of trimyristin (MMM) and tripalmitin (PPP) with different mole fraction (xPPP) to further investigate the formation mechanism of such super water-repellent surfaces. The hydrophobicity change of the MMM/PPP surfaces was monitored by the measurements on time-dependent contact angle. It has been found that all the mixture samples can form super water-repellent surfaces spontaneously under appropriate heat treatment conditions. However, the time (t150) needed to exhibit super water-repellency for an MMM/PPP surface, incubated at a specific temperature, decreases slightly along with xPPP at the range from 0 to 0.2, while the t150 value increases steadily at the xPPP range from 0.2 to 1.0. The plot of t150 versus xPPP has the similar trend to the solid-liquid phase diagram with a eutectic point of the binary system determined by differential scanning calorimetry (DSC). The fractal dimensions (FDs) describing roughness of these surfaces were calculated by the box-counting method from the scanning electron microscopy (SEM) images of different water-repellent surfaces and their cross sections. Kinetic constants of the formation of super water-repellent surfaces are further obtained and quantitatively compared by the correlation on the basis of the time-dependent contact angles.Graphical abstract(a) Time-dependent contact angles and some photographs of water droplets on MMM/PPP mixture surfaces with the composition of xPPP = 0.4 incubated at different temperatures. (b) SEM images and cross-sectional trace curves of MMM/PPP mixture surfaces (xPPP = 0.6) incubated at 40 °C for 150 min with the contact angle of 153.5°.Highlights► Binary mixtures of trimyristin and tripalmitin (MMM/PPP) are used in this work. ► All binary mixtures can form super water-repellent surfaces spontaneously. ► Phase diagram of the binary mixtures is determined by DSC. ► Kinetic constants for the formation of super water-repellent surfaces are obtained.

Densities, viscosities, and refractive indices are investigated for binary mixtures of 1,2,3,4-tetrahydronaphthalene with several n-alkanes, namely, octane, nonane, and decane, at different temperatures (293.15 K, 298.15 K, 303.15 K, and 313.15 K) and atmospheric pressure. The values of density (ρ) of the compounds were used to compute excess molar volume (VmE) of the solution. The refractive indices of these binary systems were also determined over the whole concentration range at 293.15 K and 303.15 K.

A novel ionic liquid N-ethyl piperazinium propionate, [NEPP], was prepared, and the densities and viscosities for the binary mixtures of [NEPP] with methanol, ethanol, n-propanol, and n-butanol were measured over the whole concentration range at (298.15, 303.15, 308.15, and 313.15) K and 0.1 MPa. The data of the excess molar volume, VmE, were calculated and fitted with the Redlich–Kister type polynomial equation. The values of VmE of the investigated systems are all negative, indicating that the ion–dipole interactions play important roles between the molecules of the ionic liquid and the alcohols.

Measurement on bubble-point vapor pressure, density and viscosity at several temperatures for binary mixtures tricycle [5.2.1.02.6] decane (JP-10), a high density fuel, and methylcyclohexane (MCH) were carried out. The correlation between vapor pressures and equilibrium temperatures of each mixture was performed and the Antoine equation parameters were given correspondingly. The experimental VLE data were correlated with the Wilson model. From the density and viscosity data, excess volume, VmE, and viscosity deviation, Δη, for the binary mixtures were calculated and fitted with the Redlich–Kister equation. The viscosities correlated with several semi-empirical equations were also performed. The excess molar volumes and the viscosity deviations are negative over the entire composition range.Highlights► The bubble-point vapor pressure, density and viscosity at several temperatures for binary mixtures of tricycle [5.2.1.02.6] decane (JP-10) and methylcyclohexane (MCH) are measured in this paper. ► Excess volume, VmE, and viscosity deviation, Δη, are negative over the entire composition range. The results were fitted with the Redlich–Kister equation. ► The viscosities were correlated with four semi-empirical equations and the Grunberg–Nissan expression gives best correlation results.

Self-assembled silver nanoparticles with an average diameter of 5 nm have been successfully fabricated by reduction of Ag+ with ascorbic acid in the mixture of water, alkylamine, and oleic acid. Thermogravimetry (TG), differential scanning calorimetry (DSC), and contact angle measurements indicate that oleic acid molecules are well capped on the silver nanoparticles. The effects of temperature and reaction-medium pH on the morphology and composition of the silver nanoparticles are discussed. A decrease in pH leads to a tendency to produce silver nanorods and nanospheres. The temperature can affect the thickness of the organic layer on the surfaces of the silver nanoparticles. The stabilities of the silver nanoparticles in the nanofluids were monitored at different temperatures. Thermal conductivity enhancements were determined in kerosene-based nanofluids with the prepared silver nanoparticles. The surface-capped silver nanoparticles exhibited excellent dispersity in kerosene and conventional organic solvent such as n-hexane and chloroform. The highly dispersible silver nanoparticles are therefore suitable for the preparation of oil-based nanofluids.

Thermal cracking reactions of a kerosene-based aviation fuel were carried out in a constant-volume reactor, and the kinetics were investigated at different temperatures from 663 to 703 K. The gaseous and liquid products collected from the efflux cooled to room temperature at atmospheric pressure were determined by gas chromatography and gas chromatography−mass spectrometry. The major hydrocarbon components in the gaseous phase were methane, ethane, ethene, propane, and propene; methane had the highest content among them. In the liquid effluence, the contents of components with carbon atom number higher than C11 decreased while those with lower carbon atom number clearly increased with the temperature or reaction time increasing. The gas yield ratios increased with the reaction temperature or time increasing. The thermal cracking kinetic process was correlated well by the pseudo first-order kinetic equation. The correlation followed that the rate constants were in the range 0.163 × 10−2 h−1 at 663 K to 2.809 × 10−2 h−1 at 703 K. The Arrhenius parameters were then derived with the values of the apparent activation energy Ea of 280 ± 6.5 kJ mol−1 and the logarithm of the pre-exponential factor, log A = 19.3 ± 0.5. The values were in reasonable agreements with those for the first-order decomposition of the chain alkanes such as n-dodecane.

Coking of three model compounds of hydrocarbon fuel—n-heptane, cyclohexane, and tricyclo[5.2.1.02.6]decane (JP-10)—during their thermal cracking processes under supercritical condition (873.15 K, 4.1 MPa) has been investigated. The product distributions of the thermal cracking are analyzed by gas chromatography−mass spectrometry (GC-MS). The morphology and microstructures of the cokes are characterized by the techniques of scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The results show that chemical structures play important roles in the thermal stability and coking property of the fuels. The thermal cracking conversion of n-heptane is highest, and the coke yield of JP-10 is highest under the same conditions. It is interestingly observed that the morphologies of the cokes produced from the thermal cracking of three fuels are quite different, which from n-heptane, cyclohexane, and JP-10 are in the forms of carbon nanofilaments, carbon nanotubes, and irregular carbon particles, respectively.

Vapor pressures for mixtures of a hydrocarbon fuel with ethylene glycol dimethyl ether (EGDME) and diethylene glycol dimethyl ether (DEGDME) were measured by comparative ebulliometry with inclined ebulliometers. Experimental data of vapor pressures and equilibrium temperatures for each mixture were correlated by the Antoine equation. The pseudo-binary vapor−liquid equilibrium (VLE) data were calculated with a non-random two liquid (NRTL) model. Prediction of the vapor pressures for the hydrocarbon fuel from the American Petroleum Institute (API) equations gave relatively satisfactory results. Furthermore, thermal conductivities for the pseudo-binary systems were measured at 273.15 and 298.15 K by means of a relative transient calorimeter. The data were compared to those calculated from the Jamieson equation. These results could provide important information on the development of oxygenate-blended fuels.

The density, viscosity, and vapor pressure for binary mixtures of tricyclo [5.2.1.02.6] decane (JP-10), a high-energy density hydrocarbon fuel, with diethyl carbonate are presented. Excess volume, VmE, and viscosity deviation, Δη, for the binary mixtures have been calculated. Positive values of VmE, negative values of Δη, and positive deviations from Raoult’s law for the vapor pressures are observed. The deviation results are discussed in terms of the changes of molecular interactions in the mixtures, and they are fitted with the Redlich−Kister equation. The viscosities have also been correlated with several semiempirical equations. These physical property data and calculations provide valuable information on the development and application of new high-energy density hydrocarbon fuels.

Thermal cracking of a high density hydrocarbon fuel, JP-10 (exo-tetrahydrodicyclopentadiene), was studied on a batch reactor under different pressures. The effluent was cooled and collected at room temperature and atmospheric pressure. The gaseous and liquid components were quantitatively determined by gas chromatography and gas chromatography−mass spectrometry, respectively. The conversion of JP-10 has relatively low value at atmospheric pressure and increases under pressure. With an increase of the pressure, the relative content of ethene or propene decreases and that of methane, ethane, or propane increases simultaneously. In the liquid products, cyclopentane, cyclopentene, 1,3-cyclopentadiene, and cis-bicyclo[3.3.0]oct-2-ene are found to be major components. Substituted cyclopentene, benzene, toluene, and naphthalene are also observed under high pressures and temperatures. A probable mechanism of the thermal cracking of JP-10 is proposed to explain the product distribution. The process of isomerization might be dominating for liquid product formation during the thermal cracking under elevated pressure.

Enthalpies of solution and transfer of glycine, l-alanine, l-valine, l-serine and l-threonine from water to aqueous surfactant (sodium dodecyl sulfate or dodecyltrimethylammonium bromide) solutions have been determined at 298.15 K by isothermal calorimetry. Dehydration and ion–ion interactions are important at low concentrations of the surfactant. Hydrophobic–hydrophobic interactions become primary when the amino acid molecules insert into the hydrophobic tail groups of the micelles. These phenomena can be explained with the hydration co-sphere overlap model.

Enthalpies of solution of five amino acids, glycine, l-alanine, l-valine, l-serine, and l-threonine in aqueous solutions of three quarternary ammonium surfactants, [CnH2n+1(CH3)2NCH2CH2OH]Br (n = 12, 14, 16), have been measured at 298.15 K with a microcalorimeter. Enthalpies of transfer of amino acids from water to aqueous surfactant solutions have been derived. It has been observed that, at relatively low concentrations of the surfactant solutions, amino acids are still in the water phase and mainly interact with the hydrophilic head groups of the surfactant molecules. With an increase of the concentration of the surfactant solutions, the microenvironment of amino acids changes, and the molecules might insert into the micelles and interact with the hydrophobic tail groups of the surfactant molecules. The results are discussed in terms of a delicate balance of hydrophobic and hydrophilic interactions and differences in the molecular structure of amino acids.

Viscosity (η) and density (ρ) values are reported for binary mixtures of N-methylpiperazine (NMP) with methanol, ethanol, n-propanol, iso-propanol, n-butanol and iso-butanol over the entire range of mole fraction at 293.15, 298.15, and 303.15 K and atmospheric pressure. The viscosity deviation (Δη), excess molar volume (VE), and excess Gibbs energy of activation (G*E) have been calculated. These results were fitted with Redlich–Kister type polynomial equation. All the investigated systems exhibit very large positive values of Δη and G*E, and negative values of VE over the whole composition range. The obvious deviations attribute to the strong cross association between the alkanol and NMP molecules through the hydrogen bond of OH⋯⋯N. The temperature has significant effect on Δη and relatively slight effect on VE and G*E. From the experimental data, the thermodynamic functions of activation have been estimated for each binary mixture. The viscosity data have been correlated with several semi-empirical equations. Two-parameter equation of McAllister can give satisfactory results.