N-octane System Research Articles

Behavior of the SDS/1-butanol and SDS/2-butanol mixtures at the water/n-octane interface through molecular dynamics simulations

Interfacial properties of water/SDS+1-butanol/n-octane and water/SDS+2-butanol/n-octane systems have been determined using MD simulations with the aim of studying the molecular interactions between alcohols and SDS when are located at the water/n-octane interface. Also, interfacial properties of water/1-butanol/n-octane, water/2-butanol/n-octane and water/SDS/n-octane systems were determined to validate the used force fields. The relations of SDS/alcohol equal to 16:25, 4:5, 1:1 and 6:5 were used. The g(r)s were evaluated to determine effective interaction between the SDS and alcohol molecules at the interface. The g(r)s demonstrate that –OSO3− group present an effective interaction with the hydroxyl group of the alcohols. This indicate that hydroxyl groups can be located in the gap that exist between the –OSO3− groups of the SDS molecules. Therefore, interfacial activity of the SDS/alcohol monolayer is better, favoring the stability of the protective film and the reduction of the interfacial tension. This help to the formation and stability of the microemulsion.

N-Propanol과 n-Octane 혼합물의 최소자연발화온도의 예측

화재 및 폭발 방호를 위해서 문헌에서의 최소자연발화온도 값을 사용하는 것이 일반적이다. 본 연구에서, n-Propanol+n-Octane 계의 최소자연발화온도는 ASTM E659 장치를 이용하여 발화지연시간으로부터 측정하였다. 2성분계를 구성하는 n-Propanol과 n-Octane의 측정된 최소자연발화온도는 각 각 <TEX>$435^{\circ}C$</TEX>와 <TEX>$218^{\circ}C$</TEX> 였다. 그리고 두 개의 2성분계에서 측정된 발화지연시간은 제시된 식에 의한 예측된 발화지연시간과 적은 평균절대오차에서 일치하였다. The lowest values of the AITs(Autoignition temperatures) in the literature were normally used fire and explosion protection. In this study, the AITs of n-Propanol+n-Octane system were measured from ignition delay time(time lag) by using ASTM E659 apparatus. The AITs of n-Propanol and n-Octane which constituted binary systems were <TEX>$435^{\circ}C$</TEX> and <TEX>$218^{\circ}C$</TEX>, respectively. The experimental ignition delay time of n-Propanol+n-Octane system were a good agreement with the calculated ignition delay time by the proposed equations with a few A.A.D.(average absolute deviation).

Measurement and prediction of high-pressure vapor–liquid equilibria for binary mixtures of carbon dioxide + n-octane, methanol, ethanol, and perfluorohexane

We report the measurement of high-pressure vapor–liquid equilibrium data for binary mixtures of carbon dioxide + n-octane, +methanol, and +ethanol systems at 313.14 K and carbon dioxide + perfluorohexane at 303.15–323.15 K. The experimental data were collected using a new simple apparatus for measuring high-pressure vapor–liquid equilibria and correlated using a modified SRK equation with the three-parameter conventional mixing rule proposed by Adachi and Sugie. The SAFT-VR equation of state has also been used to predict the phase behavior and found to be in good agreement with experimental data. For the carbon dioxide + methanol, carbon dioxide + ethanol and carbon dioxide + perfluorhexane systems simple Lorentz–Berthelot combining rules can be used to determine the cross interactions and predict the phase behavior. For the carbon dioxide + n-octane system cross interaction parameters fitted to experimental data are needed in order to capture the non-ideal phase behavior exhibited by this system.

Vapor–liquid equilibrium data for the nitrogen + n-octane system from (344.5 to 543.5) K and at pressures up to 50 MPa

A static-analytical apparatus with visual sapphire windows and pneumatic capillary samplers has been used to obtain new vapor–liquid equilibrium data for the N 2 + n-octane system over the temperature range from (344.5 to 543.5) K and at pressures up to 50 MPa. Equilibrium phase compositions and vapor–liquid equilibrium ratios are reported. The new results were compared with solubility data reported by other authors. The comparison showed that the solubility data reported in this work at 344.5 K are in good agreement with those determined by others at 344.3 K. The experimental data were modeled with the PR and PC-SAFT equations of state by using one-fluid mixing rules and a single temperature-independent interaction parameter. Results from the modeling effort showed that the PC-SAFT equation was superior to the PR equation in correlating the experimental data of the N 2 + n-octane system.

Volumetric properties of 1-iodoperfluorohexane+n-octane binary system at several temperatures

New densities are reported over the whole composition range for 1-iodoperfluorohexane+n-octane system at temperatures from 288.15 to 308.15 K at atmospheric pressure. These data have been used to compute the excess molar volumes, VmE. Large positive VmE values have been obtained over the entire range of composition, which increases when the temperature rises. The experimental data were used to calculate the isobaric thermal expansivity, and the quantities (∂VmE/∂T)p and (∂HmE/∂p)T. Furthermore, the results have been used to investigate the volumetric prediction ability of the equations of state Soave–Redlich–Kwong, Peng–Robinson, Patel–Teja and Soave–Redlich–Kwong with volume translation.

Measurement and correlation of liquid–liquid equilibria and partition coefficients of benzothyophene and benzothyophene 1,1-dioxide for acetonitrile + n-octane system

The reductions of sulfur content in gasoline and diesel fuel are great environmental concern to reduce the motor vehicle emissions. Oxidative desulfurization in acetonitrile biphasic system, proposed in recent years, can oxidize the unreactive sulfur compounds in the hydrodesulfurization. In this work, therefore, liquid–liquid equilibria (LLE) for acetonitrile+n-octane and+n-decane systems were measured with the tie-line measurement. The partition coefficients of benzothyophene, a major sulfur-containing compound in gasoline, and benzothyophene 1,1-dioxide, a major product of benzothyophene oxidative desulfurization reaction, for acetonitrile+n-octane system were also measured. Furthermore, the LLE was calculated with ASOG activity coefficient model to see the applicability of the model.

Pressure and temperature dependence of the excess thermodynamic properties of binary dimethyl carbonate + n-octane mixtures

In this work we report several excess thermodynamic properties for the dimethyl carbonate + n-octane system in an effort to better understand their behavior over wide temperature and pressure ranges. From previous experimental pVTx data for this system, the changes in the excess molar Gibbs energies, in the excess molar entropies, and in the excess molar enthalpies due to pressure have been determined over a wide temperature range and for pressures up to 25 MPa. A correlation of the excess volume as a function of pressure was used for each composition and temperature, together with a new, recently proposed equation for the excess molar volume as a function of temperature, pressure, and composition. Excess molar enthalpies and excess molar Gibbs energies at 298.15 K and for pressures up to 25 MPa were calculated using literature data at atmospheric pressure. Furthermore, the excess isothermal compressibility, the excess isobaric expansivity, and the excess internal pressure were calculated. The expression for the internal pressure of an ideal mixture suggested recently by Marczak has been used.Key words: excess thermodynamic properties, dimethyl carbonate, n-octane, high pressure.

Thermodynamic Properties of Aqueous Solutions of Alkanes under Supercritical Conditions

P–V–T–X relationships for the water–methane, water–n-pentane, water–n-hexane, water–n-heptane, and water–n-octane systems are derived by piezometry at a constant volume in the vicinity of the critical point of water (647.096 K) and up to 673.15 K at pressures up to 40 MPa and alkane mole fractions of 0–1.0. Conditions are determined under which real mixtures behave as an ideal gas or have a constant compressibility factor. It is demonstrated that the concentration dependence of the partial molar volumes of alkanes in the range of small concentrations is asymptotic if the isothermal isobar of the solvent is critical. The molecular parameters of the equation of state that is based on perturbed-hard-chain theory are determined and used in the calculation of thermodynamic parameters for this class of solutions.

FT-IR SPECTROSCOPY OF NITRIC ACID IN TBP/OCTANE SOLUTION1*

Infrared studies for the HNO3/0.73 M TBP n-octane system are reported. Two extracted species, TBP · HNO3 and TBP · 2HNO3, were identified in the organic phase. The concentration of the individual species was determined by the analysis of the vibrational band at ∼1650 cm−1. The band at 1648 cm−1 was assigned to the monosolvate TBP · HNO3 and the band at 1672 cm−1 to the hemisolvate TBP · 2HNO3. The infrared spectra revealed that with respect to the P═O bond, as well to each other, the HNO3 molecules in the hemisolvate are spectrally non-equivalent. The predominant structure of TBP · 2HNO3 involves the chain HNO3 dimer. Some ionic NO3 − and hydronium ions were identified in this system but only during formation of the monosolvate. The analyses performed in this system can serve for the characterization of HNO3 in related systems in the presence of metal species. *Work performed under the auspices of the office of Basic Energy Sciences, Division of Chemical Sciences, Department of Energy, under contract W-31-109-ENG-38.

Isothermal vapor-liquid equilibria for the 2-butanone + benzene + n-octane system

Abstract Yahiaoui, A., Gonzalez, J.A., Ait-Kaci, A., Jose, J. and Kehiaian, H.V., 1994. Isothermal vapor-liquid equilibria for the 2-butanone + benzene + n-octane system. Fluid Phase Equilibria, 98: 179–187. Vapor-liquid equilibrium (VLE) data were measured for the ternary 2-butanone(1) + benzene(2) + n-octane(3) system using an isoteniscope of our design over the temperature range (298.05–323.10) K. The data are examined on the basis of the DISQUAC group contribution model. In terms of DISQUAC, the mixture is characterized by three types of contact: aliphatic/ketone, aliphatic/benzene and benzene/ketone. Only for the latter, the interchange coefficients are not available in the literature, and are estimated in this work using VLE and excess enthalpy data for the binary 2-butanone + benzene system. Applying the same parameters to the ternary system under study, DISQUAC yields total pressures values which are 3% lower than the experimental results.

Thermodynamic properties of the mixtures of a dioxanonane isomer + n-octane at 298.15 K : Part II. Excess molar volumes and excess isentropic and isothermal compressibilities (measurements of density and speed of sound)

Densities, ϱ, and speeds of sound, u, of six mixtures of an isomer of the diethers 2, m- or 3, n-dioxanonane ( m = 5, 6, 7, 8; n = 6, 7) + n-octane were measured at 298.15 K. The densities provided excess molar volumes V E, and excess isothermal compressibilities, k T E, of the mixtures were estimated using heat capacities and isentropic compressibilities, k s e, obtained from measurements of density and speed of sound. The excess volumes were positive and parabolic, ranging from 0.5 to 0.7 cm 3 mol −1 and depending on both the density and dipole moment, μ, of the pure diethers. The excess isentropic compressibilities are positive and parabolic, except for the 2,8-dioxanonane + n-octane system, where the curve is flattened at large diether mole fractions and the maximum shifts to the small mole fractions. The excess isothermal compressibilities are almost parallel to the excess isentropic compressibilities but are about 20% higher. The speeds of sound, isentropic and isothermal compressibilities of the pure diethers are all very similar to each other and strongly correlated with their densities.

Alkyl nitrate formation from the nitrogen oxide (NOx)-air photooxidations of C2-C8 n-alkanes

The yields of alkyl nitrates formed in the NO/sub x/-air photooxidations of the homologous series of n-alkanes from ethane through n-octane have been determined at 299 +/- 2K and 735 torr total pressure for two different chemical systems. Alkyl peroxy radicals were generated by reaction of the n-alkanes with OH radicals (generated from the photolysis of methyl nitrite in air) or Cl atoms (from photolysis of Cl/sub 2/ in air). The alkyl nitrate yields obtained from the two systems, corrected for secondary reactions, were in agreement within the experimental errors and increased monotonically with the carbon number of the n-alkane, from less than or equal to1% for ethane to approx. 33% for n-octane, with the yields apparently approaching a limit of approx. 35% for large n-alkanes. The relative yields of the various secondary alkyl nitrate isomers in the n-pentane through n-octane systems were in good agreement with those expected from OH radical or Cl atom reaction with the corresponding secondary C-H bonds. However, the relative yields of the primary alkyl nitrates in the propane and butane systems were a factor of approx. 2 lower than expected. The data are consistent with the alkyl nitrates being formed almost entirely from themore » reaction of peroxy radicals with NO, and the ratios of the corrected alkyl nitrate yields thus reflect the fraction of RO/sub 2/ radicals which react with NO to form alkyl nitrates. These nitrate yields from the reaction of RO/sub 2/ radicals with NO are important inputs into chemical computer models of the atmospheric NO/sub x/-air photooxidations of the large n-alkanes.« less