Mixtures Of Nonpolar Gases Research Articles

Competitive and Synergistic Adsorption of Mixtures of Polar and Nonpolar Gases in Carbonaceous Nanopores.

Most adsorption applications involve mixtures, yet accurate predictions of the adsorption of mixtures remain challenging, in part due to the inability to account for the interplay between adsorbate-adsorbate and adsorbate-adsorbent interactions. This study involves a comprehensive Monte Carlo simulation of the adsorption of two groups of mixtures (namely, supercritical and subcritical ones) in carbon nanopores and quantifies Henry's constants, isotherms, energetics, and density distributions in the pores. When interadsorbate interactions are negligible (e.g., in supercritical mixtures such as mixtures of nonpolar gases), adsorbates behave like ideal gases and the adsorption isotherm can be predicted with the ideal adsorbed solution theory (IAST). However, when interadsorbate interactions become significant, IAST fails. This study reveals that (1) in mixtures of polar and nonpolar gases, the stronger intermolecular interaction for the polar constituent leads to synergistic adsorption that causes the nonpolar adsorbate to desorb and (2) for mixtures of polar gases, such as ethanol and water, the adsorbate-adsorbate interactions are so dominant that the unfavorable adsorbate-adsorbent interactions are overcome, such that water adsorbs onto the hydrophobic adsorbent. The competitive and synergistic interactions highlighted here are expected to be valuable in enhancing gas separations.

Brines at high pressure and temperature: Thermodynamic, petrologic and geochemical effects

A number of observations point to the participation of brines in high-grade metamorphic processes. These include findings of alkali and alkaline-earth halides as daughter crystals in fluid inclusions, appreciable concentrations of Cl measured in amphiboles, biotite, scapolite and apatite, and direct observations on high-temperature halides present in the intergranular space in high-grade rocks. This paper reviews some thermodynamic, petrologic and geochemical effects of these brines. Thermodynamic mixing properties of concentrated water–salt fluids at high pressure (P) and temperature (T) differ greatly from those of water–non-polar gas mixtures: the former are characterized by a large negative deviation from ideal solutions, while the latter exhibit positive deviation from ideality. The contrasting behavior has three major petrologic implications. First, compared to mixtures of water and non-polar gases, brines more strongly increase the melting temperature of quartzofeldspathic rocks and more strongly decrease dehydration temperature of water-bearing minerals. This allows a wide P–T window in which subsolidus deep-crustal metasomatism may take place at relatively low H2O activity (aH2O) via migrating fluids. In addition, above 2–3kbar, brine-saturated solidi for simple granite melting show positive dP/dT at constant H2O mole fraction (XH2O), favoring ascent of fluid-saturated liquids. Finally, a large miscibility gap exists in H2O–CO2–salt ternaries at lower crustal conditions, which may concentrate salts in a separate phase and help explain the common observation of CO2-rich inclusions in high-grade minerals. We discuss three geochemical consequences of high-grade brines. We report new experimental data on melting of a model granitoid liquid (69wt% NaAlSi3O8, 31wt% SiO2) at 2kbar in the presence of aqueous NaCl solutions ranging in concentration from a salt mole fraction (XNaCl) of 0.1–0.3. The results show that Na preferentially partitions into the silicate liquid, enriching the coexisting fluid in HCl. This hydrolysis effect, known previously for granite melts equilibrated with dilute solutions, therefore also extends to more saline brines. Mineral solubilities depend strongly on salt concentration in the coexisting fluid. Below 5kbar at 700°C, quartz initially salts in with addition of NaCl to H2O, reaches a maximum, and then declines; however, it salts out at all XNaCl at higher P. At granulite-facies P–T conditions, the solubilities of other oxide and silicate minerals (corundum, wollastonite, grossular) salt in and then either reach a plateau or salt out slightly at high XNaCl. In contrast, the solubility of Ca–salt minerals increases exponentially with rising XNaCl. The solubility patterns reflect variations in complexing and H2O activity in the brine. Partitioning of REE between rock forming minerals and brines, and between felsic melts and brines, differs strongly from that between minerals, melts and water (±non-polar gas). Brines extract REE from the melts much more efficiently, and LREE are extracted more efficiently than HREE. This effect may contribute to the decreased La/Yb ratio that accompanies the overall decrease in bulk REE concentration in leucosomes relative to their parental rocks (paleosomes) that has been documented from amphibolite- and granulite-grade migmatite complexes.

Generalization and calculation of the thermal diffusion factor of binary hydrogen-containing gaseous mixtures

The results of generalization of experimental data on the thermal diffusion factor α T of hydrogen-containing gaseous mixtures within the framework of similarity theory have been given. The calculated relation which makes it possible to predict the thermal diffusion factor of hydrogen-containing mixtures of nonpolar gases with a limited body of data on the substance has been obtained. The α T values of mixtures of hydrogen with inert gases, including radon Rn, and with N2, SiH4, and GeH4 in the temperature interval 100–1500 K have been calculated.

Vapour-liquid and liquid-liquid phase equilibria of binary mixtures containing helium: comparison of experiment with predictions using equations of state

The unlike interaction parameters for binary mixtures of helium + non-polar gases are obtained by comparing experimental critical data with calculations using the Guggenheim and Heilig-Franck equations of state. These interaction parameters and equations of state are used to predict a priori both the vapour-liquid and liquid-liquid equilibria for helium + non-polar gas mixtures. The predicted phase diagrams are compared with experimental data for a wide range of pressure, temperature and composition. Good agreement between theory and experiment is obtained for the isobaric temperature-composition phase behaviour and isothermal pressure-composition phenomena can be predicted qualitatively.

Cryovolcanism on the icy satellites

Evidence of past cryovolcanism is widespread and extremely varied on the icy satellites. Some cryovolcanic landscapes, notably on Triton, are similar to many silicate volcanic terrains, including what appear to be volcanic rifts, calderas and solidified lava lakes, flow fields, breached cinder cones or stratovolcanoes, viscous lava domes, and sinuous rilles. Most other satellites have terrains that are different in the important respect that no obvious volcanoes are present. The preserved record of cryovolcanism generally is believed to have formed by eruptions of aqueous solutions and slurries. Even Triton's volcanic crust, which is covered by nitrogen-rich frost, is probably dominated by water ice. Nonpolar and weakly polar molecular liquids (mainly N2, CH4, CO, CO2, and Ar), may originate by decomposition of gas-clathrate hydrates and may have been erupted on some icy satellites, but without water these substances do not form rigid solids that are stable against sublimation or melting over geologic time. Triton's plumes, active at the time of Voyager 2's flyby, may consist of multicomponent nonpolar gas mixtures. The plumes may be volcanogenic fumaroles or geyserlike emissions powered by deep internal heating, and, thus, the plumes may be indicating an interior that is still cryomagmatically active; or Triton's plumes may be powered by solar heating of translucent ices very near the surface. The Uranian and Neptunian satellites Miranda, Ariel, and Triton have flow deposits that are hundreds to thousands of meters thick (implying highly viscous lavas); by contrast, the Jovian and Saturnian satellites generally have plains-forming deposits composed of relatively thin flows whose thicknesses have not been resolved in Voyager images (thus implying relatively low-viscosity lavas). One possible explanation for this inferred rheological distinction involves a difference in volatile composition of the Uranian and Neptunian satellites on one hand and of the Jovian and Saturnian satellites on the other hand. Perhaps the Jovian and Saturnian satellites tend to have relatively "clean" compositions with water ice as the main volatile (ammonia and water-soluble salts may also be present). The Uranian and Neptunian satellites may possess large amounts of a chemically unequilibrated comet-like volatile assemblage, including methanol, formaldehyde, and a host of other highly water- and ammonia-water-soluble constituents and gas clathrate hydrates. These two volatile mixtures would produce melts that differ enormously in viscosity The geomorphologic similarity in the products of volcanism on Earth and Triton may arise partly from a rheological similarity of the ammonia-water-methanol series of liquids and the silicate series ranging from basalt to dacite. An abundance of gas clathrate hydrates hypothesized to be contained by the satellites of Uranus and Neptune could contribute to evidence of explosive volcanism on those objects.

Application of the theory of similarity for purposes of generalizing the thermal-diffusion factor for mixtures of multiatomic nonpolar gases

The thermal-diffusion factor of 14 nonpolar-gas mixtures has been generalized on the basis of similarity theory. The theoretical values of αth obtained on the basis of this generalized relationship are compared with the experimental data.

The equation of state for a mixture of nonpolar gases at moderate densities

The virial equation of state for the (12-7, δ) pair model potential is extended to mixtures of nonpolar gases. The applicability of the equation is examined, and it is shown that calculations agree with experiment within the error of the measurements.

Mass-spectrometric investigation of the kinetics and the deactivation of C4H8+ and (C4H8)2+ ions formed by photoionization of isobutene in nonpolar gas mixtures

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMass-spectrometric investigation of the kinetics and the deactivation of C4H8+ and (C4H8)2+ ions formed by photoionization of isobutene in nonpolar gas mixturesKenzo Nagase and Jan A. HermanCite this: J. Phys. Chem. 1984, 88, 7, 1368–1373Publication Date (Print):March 1, 1984Publication History Published online1 May 2002Published inissue 1 March 1984https://doi.org/10.1021/j150651a026RIGHTS & PERMISSIONSArticle Views15Altmetric-Citations3LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (738 KB) Get e-Alerts

Correlation for the third virial coefficient usingTc,Pcand ω as parameters

AbstractAn empirical correlation for the third virial coefficient of nonpolar gases is developed. The correlation requires a knowledge of the critical temperature, critical pressure and acentric factor of the compounds for the prediction of third virial coefficients in the absence of experimental data. The use of the correlation for mixtures of nonpolar gases, including quantum gases, requires one binary parameter for each binary interaction. Predictions are in good agreement with reported experimental data and with the values obtained with existing correlations.

Generalization of experimental data regarding the thermal conductivity of gas mixtures from the structural point of view

On the basis of theoretical relationships and a generalization of experimental data, an equation is derived for calculating the thermal conductivity of binary mixtures of nonpolar gases.

Experimental data and procedures for predicting thermal conductivity of binary mixtures of nonpolar gases

The thermal conductivities of Ne, Ai, Kr, Xe, Hz, 02 Nz, and 02 are measured using a thick hot-wire metal cell at five temperatures in the range 40-175OC. The solution of the heat balance equation as developed by Oldham andvluchsinger is employed, and we estimate an accuracy of 1-2% in our recommended absolute conductivity values. In this temperature range, the thermal conductivities of the binary systems Ne-Hz, Ne-Nn, Ne-02, Hz-Dz, Nz-Dz, Hz-Nz, N2-02, Kr-Hn, Xe-Hz, Xe-Dz, and Xe-Ar are also determined as a function of composition. On the basis of these experimental data, the methods of prediction of thermal conductivity of mixtures due to Hirschfelder, Mason and Saxena, Mathur and Saxena, Lindsay and Bromley, Ulybin et al., and Burgoyne and Weinberg are examined with a view to ascertain their relative accuracies. The framework of Chapman-Enskog kinetic theory in conjunction with the experimental data on thermal conductivity is used to generate the diffusion and viscosity coefficients for Xe-Ar, Xe-Dn, Ne-Hz, Ne-Nn, and Ne-02, as representative systems. Recently Saxena and Gupta (26) have reported experimental thermal conductivity data on eight pure gases, four of their binary, two ternary and two quaternary systems as a function of composition. The measurements were taken on a metal hot-wire cell with a thick platinum wire as a hot surface, and at temperatures of 40, 65, and 93'C. Here we report the thermal conductivities of the binary systems Ne-H2, Ne-N2, Ne-On, HZ-Dn, NZ-DZ, Hn-Nz, Nz02, Kr-Hz, Xe-H2, Xe-D2, and Xe-Ar as a function of composition and of the related eight pure gases at 40°, 65, 930, 950, 135, and 175C, using the same hot-wire cell. The details of the experimental arrangement, procedure of calculation, and comparisons of the experimental conductivity values with some of the semitheoretical procedures are given in the following sections. EXPERIMENTAL

Intermolecular forces in gaseous ammonia and in ammonia – nonpolar gas mixtures

Intermolecular potential parameters for ammonia have been determined for the Stockmayer–Kihara function using experimental second virial coefficient, diffusivity and viscosity data of binary mixtures with argon, methane, nitrogen, and oxygen. The parameters U0/k = 215 °K, σ(core-to-core) = 2.70 Å and a* = 0.2 reproduce essentially all of the data nearly within experimental error and accurately reproduce pure ammonia transport properties. Upon considering both physical and chemical contributions to the second virial coefficient of ammonia, the apparent standard-state hydrogen-bond enthalpy for chemical dimerization is −3.2 kcal/mole while the vibrational entropy change is 20.2 cal/mole °K, indicating weak association.

Thermal relaxation and heat transfer in non-polar gas mixtures

The theory recently given by Saksena and Sharma in 1969 for the thermal conductivity of relaxing non-polar gases has been extended to mixtures involving non-polar polyatomic gases. Calculations have been performed on the systems O2-He, N2-He and O2-N2. The results obtained are in good agreement with the experimental values.

Calculation of viscosity and diffusion coefficients of nonpolar gas mixtures at ordinary pressures

Calculation of viscosity and diffusion coefficients of nonpolar gas mixtures at ordinary pressures

The viscosity of nonpolar gas mixtures at moderate and high pressures

AbstractA method has been developed for the calculation of the viscosity of nonpolar gas mixtures at moderate and elevated pressures from the molecular weights and critical constants of the components. By the use of available experimental data and appropriate pseudocritical constant rules, results obtained previously for the viscosity of pure gases have been extended to mixtures. Viscosity values calculated by the method developed in this study for a number of nonpolar gas mixtures were found to reproduce reported values with a high degree of accuracy.

Viscosity of polar gas mixtures: Wilke's method

The simple expression of Wilke for viscosity which has proved very successful for mixtures of nonpolar gases has been examined here for mixtures involving polar gases also. The success achieved here is comparable to that obtained for nonpolar gases. A modification of the original procedure of Wilke has been suggested and tested successfully. It will be particularly useful where pure viscosity data may be lacking.

Approximate Formulas for the Viscosity and Thermal Conductivity of Gas Mixtures

Approximate expressions for the viscosity and thermal conductivity of gas mixtures have been derived from the rigorous kinetic theory formulas. Three levels of approximation are distinguished, with the third approximation rigorous for binary mixtures. The first approximation for mixture viscosity is found to be very nearly equivalent to empirical expressions known heretofore. The first and second approximations for mixture conductivity have been compared with rigorous calculations for binary mixtures of nonpolar gas pairs; the first approximation has an average error of 2.6% while the second approximation reduces this error to 0.5%. The second approximation accounts for the thermal conductivity of binary mixtures of polar and nonpolar gases. (It is assumed that the interchange of translational energy is abnormal for the polar-polar interaction.)

Estimating Thermal Conductivities for Nonpolar Gas Mixtures

Estimating Thermal Conductivities for Nonpolar Gas Mixtures