Solubility of propane in N-formyl morpholine

N-formyl morpholine (NFM) is a solvent that has been used to separate acid gases from gas streams. An advantage of NFM is the high solubility of acid gases compared with the low solubility of light hydrocarbons. The solubility of the light hydrocarbons in NFM is important, as the hydrocarbons constitute a loss to the process, and result in hydrocarbon emissions to the atmosphere. However, there are only a few experimental data sets dealing with the solubility of hydrocarbons in NFM. To provide data to be used in the design of plants in the natural gas processing industry, the solubility of propane (C₃H₈) in NFM was measured at 298.15, 313.15, and 343.15 K at pressures up to 20.15 MPa. The Peng-Robinson equation of state was employed to correlate the experimental data and to obtain binary interaction parameters. The binary interaction parameters were used to obtain the parameters of the Krichevsky-Ilinskaya equation and Henry's law constants for propane were calculated. Henry's law constants for propane were compared with those of hydrogen sulphide, carbon dioxide, methane, and ethane in NFM.     

Design and construction of an equipment for the determination of solubility of gases in liquids

This article presents the design and construction of a new isochoric saturation apparatus for the determination of gas solubility in liquids based on the gas drop pressure method. The major improvement of this design is the separation between the solubility and the gas cells. With this separation, the change of pressure and temperature inside the system is minimum when the gas gets in contact with the liquid and it allows degassing the liquid in an easy way. The performance of the equipment was evaluated measuring the solubility of argon and nitrogen in pure water at 283.15, 288.15, 293.15, and 298.15 K. The gas solubility was calculated according to the Henry's law. The results obtained and the comparison with literature values show that the equipment provides an accurate and precise method for determination of gas solubility in water. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3105–3109, 2017     

Correlation and Prediction of Carbon Dioxide Solubility in n‐Paraffin Systems

This work discusses high‐pressure gas solubility. Reference state is the Henry's law and a two‐parameter corresponding states model is used for the liquid phase. Pure gas is used as the vapor phase for the high‐molecular paraffin's gas‐liquid equilibrium. The systems under study are mixtures of carbon dioxide and normal paraffin up to a chain length of 44 carbon atoms. Correlated liquid compositions are in the 1 % to 3 % average absolute relative deviation range, with a maximum error of about 7 %. Using a known system as reference, the model could be used to predict solubility. In this case average absolute relative deviations are below 6 % in most cases.     

Direct measurement of gas solubilities in polymers with a high‐pressure microbalance

Solubility and diffusion data are presented for methane and carbon dioxide gases in high‐density polyethylene. The polymer was cut from extruded piping intended for use in offshore oil and gas applications. The measurements were carried out with a high‐pressure microbalance. The properties were determined from 25 to 50°C and from 50 to 150 bar for methane and from 20 to 40 bar for carbon dioxide. In general, a good agreement was obtained with similar measurements reported in the literature. The solubility followed Henry's law (linear) dependence with pressure, except at high pressures for methane, for which negative deviations from Henry's law behavior were observed. The diffusion coefficients for each of the gases in the polymer were also measured with the balance, although the uncertainty was greater than for the solubility measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1476–1488, 2004     

Physical solubility of hydrogen sulfide in several aqueous solvents

The solubility of hydrogen sulfide in several aqueous solutions was measured over the temperature range 25°C to 60°C. The solvents investigated in this work include 0 to 50% aqueous solutions of polyethylene glycol, ethylene glycol, methyldiethanolamine and diethanolamine. The amine solutions used in this work were neutralized by the addition of hydrochloric acid in order to suppress the hydrogen sulfide reaction (H₂S → H⁺ + HS^?) so that only the physical solubility of hydrogen sulfide would be measured. The solubility data determined in this work are expressed in terms of Henry's law. The Henry's law constants found in this work were correlated well by a particularly simple empirical formula based on the molecular weight of the solvent.     

Gas Permeation through Polydimethylsiloxane Membranes: Comparison of Three Model Combinations

The modeling of a gas mixture permeating through a polymeric membrane can be achieved by the combination of a mass transfer model with a thermodynamic model. In this study, three model combinations, i.e., the combination of Fick's law with Henry's law (F‐H), that of Fick's law with the UNIQUAC equation (F‐U), and that of the Maxwell‐Stefan equation with the UNIQUAC equation (MS‐U), were solved by iteration computer procedure to predict the separation performance of both binary and ternary gas mixtures permeating through a polydimethylsiloxane membrane. The predicted results were analyzed in detail and compared with experimental results. It was found that there are remarkable differences among the considered model combinations in predicting separation performance, and these differences tend to become larger with increasing solubility. Among the three considered model combinations, MS‐U gives the prediction closest to the experimental results. Its advantage over the other two model combinations should be due to the proper estimation of the permeate solubility by the UNIQUAC equation and the reasonable consideration of mass transfer resistance by the Maxwell‐Stefan equation.     

Curvature dependence of Henry's law constant and nonideality of gas equilibrium for curved vapor–liquid interfaces

Curved interfaces between coexisting vapor and liquid phases are ubiquitous in nature, and the question of whether the Henry's law is applicable for highly curved vapor/liquid interfaces remains unsolved. Using stable surface nanobubbles that have highly curved interfaces as examples, we investigate the viability of Henry's law with molecular simulations and thermodynamic analysis. We show that the prediction of Henry's law displays an increasingly deviation from the simulation results as nanobubble curvature increases. Such a curvature dependence of Henry's law constant is ascribed to the nonideality of gas in liquid phase because of the required gas supersaturation for stabilizing nanobubbles. Based on the effect, we develop a relationship for determining Henry's law constant from the level of gas supersaturation, as well as a robust relationship between gas supersaturation and nanobubble radius.     

Fluid phase equilibria in the system hydrogen sulphide-water at high pressure. Application of an extended Henry's law

Henry's law is often used to correlate the solubility of a gas in water. Such an approach is frequently employed to calculate the solubility of hydrogen sulphide in water. However, Wright and Maass [1] clearly demonstrated that the strict Henry's law did not apply to the solubility of hydrogen sulphide in water. That is, the solubility of hydrogen sulphide is not directly proportional to its partial pressure, even at seemingly low pressures. By accounting for the non-idealities in the vapour phase, Carroll and Mather [2] showed how a simple modification of Henry's law could be used for moderate pressures (up to 1 MPa). In this paper, a further extension of Henry's law is used to model the vapour-liquid equilibrium at higher pressures and temperatures. It is also applied to liquid-liquid and vapour-liquid-liquid equilibria, areas where Henry's law is rarely used.     

Soil Clean Up by in-situ Aeration. I. Mathematical Modeling

Abstract

Mathematical models are developed suitable for use in evaluating the feasibility of in-situ vapor stripping approaches for selected chemicals and site-specific environments. These models simulate the operation of both laboratory soil stripping columns and field-scale vacuum extraction wells (vent pipes). The effect of an anisotropic Darcy's constant is examined and the compressibility of the extracting gas is taken into account. The models incorporate the assumption of local equilibrium for the volatile compounds between the condensed and vapor phases. These models may use Henry's law or more complex isotherms for this equilibrium. A method is developed for calculating Henry's constant from field analytical data, and it is noted that use of Henry's constants calculated from laboratory data on solutions of volatile solutes in pure water can lead to very serious errors. It is shown that evacuation wells should be screened only down near the impermeable layer beneath the zone of stripping (unsaturated zone) for most efficient functioning     

Phase equilibria of oil,gas and water/brine mixtures from a cubic equation of state and henry's law

This paper presents the predictions and calculations of the phase equilibria of oil, gas and water/brine mixtures where the oil and gas are modeled by a cubic equation of state and where the gas solubility in the aqueous phase is estimated from Henry's law. Henry's law constants for a variety of compounds of interest to the petroleum industry are correlated against pressure and temperature. The scaled-particle theory is used to take into account the presence of salt in the aqueous phase. An extensive match of experimental data is presented, showing the adequacy of the proposed model for Henry's law constant.     

Thermodynamic and molecular insights into the absorption of H2S,CO2, and CH4 in choline chloride plus urea mixtures

Deep eutectic solvents (DESs) are a class of promising media for gas separation. In order to examine the potential application of DESs for natural gas upgrading, the solubilities of H₂S, CO₂, and CH₄ in choline chloride (ChCl) plus urea mixtures were measured in this work. The solubility data were correlated with Henry's law equation to calculate the thermodynamic properties of gas absorption processes, such as Henry's constants and enthalpy changes. Grand-canonical Monte Carlo simulations and quantum chemistry calculations were also performed to examine the mechanism of gas absorption processes. It is found that the absorption of H₂S in ChCl + urea mixtures is governed by the hydrogen-bond interaction between Cl of ChCl and H of H₂S, whereas the absorption of CO₂ and CH₄ in ChCl+urea mixtures is governed by the free volume of solvents. Based on the different behavior of gas absorption, high H₂S/CO₂, H₂S/CH₄, and CO₂/CH₄ selectivities can be achieved by adjusting the ratio of ChCl/urea in mixtures.     

Selective permeation of carbon dioxide through synthetic polymer membranes having pyridine moiety as a fixed carrier

Sorption and permeation of CO₂ were investigated by using synthetic polymer membranes having pyridine moiety or pyridine–Cu(II) complex group as a fixed carrier. The solubility data for CO₂ were interpreted by the dual sorption model, Henry's law plus Langmuir-type adsorption. The permeation results of CO₂ through the present membranes containing pyridine moiety were analyzed in terms of the partial immobilization model, while the solubilities and permeablities of O₂ and N₂ obeyed Henry's law. Permselectivity of the present membrane for CO₂ was achieved. These results were explained by the acid-base interaction between CO₂ molecules and fixed carrier in the present membrane.     

Removal of Refractory Organics by Aeration. VIII. Air Stripping of Benzene Derivatives

Abstract

The removal of several benzene derivatives from water was carried out by bubble column aeration. The presence of NaCl enhanced removal rates, while the presence of alcohols decreased them. Mixtures of two hydrophobic solutes are removed by aeration as if each were present alone. The use of the equilibrium assumption for mass transport between phases seems to be reasonably (but not perfectly) satisfactory. Henry's law constants calculated from aeration data are in fairly good agreement with those calculated from vapor pressure and solubility data. Toluene, ethylbenzene, p-xylene, chlorobenzene, p-dichlorobenzene, styrene, benzene, and 3-pentanone were studied. As predicted, the ketone is not removed by aeration at a significant rate. Removal rates of the other compounds are reasonably rapid, with Henry's law constants in the range of roughly 0.1 to 0.3 (dimensionless).     

Impact of the Versatile Aerosol Concentration Enrichment System (VACES) on Gas Phase Species

The performance of the Versatile Aerosol Concentration Enrichment System (VACES) was assessed in terms of the enrichment factor (EF) for highly soluble vapors. Gases ranged in their behavior from a slight enrichment for ammonia (EF(NH ₃ ) = 1.9 ± 0.8) to strong depletion of nitric acid (EF(HNO₃) = 0.12 ± 0.06). H₂O₂ fell in between, with EF(H₂O₂₎ averaging 0.37 (±0.25) and ranging from 0.07 and 0.91 depending on conditions. Detailed results for H₂O₂ indicate that there are two competing processes at play: soluble gases are lost to condensed water in the VACES, particularly in the saturator water bath but also other locations, depleting outlet gas-phase concentrations and resulting in EFs well below 1. Working in the opposite direction, H₂O₂ (and other soluble gases) can also be concentrated together with particles. Presumably, the gases are absorbed into the particles as they take up water, pass through the concentration step, and are released once particles are re-dried. Depending on conditions and the gas solubility, depletion and concentration play larger or smaller roles. The relative importance of these competing processes appear to follow in order of Henry's law solubilities, with modest particle-mediated concentration (resulting in EFs >1) dominating for ammonia, the least soluble gas, and loss in the water bath and other condensed water in the VACES dominating for H₂O₂ and HNO₃, which are more soluble (i.e., have higher Henry's law coefficients).     

Measurement and prediction of diffusion coefficients of supercritical CO2 in molten polymers

The solubility and diffusivity of supercritical carbon dioxide (sc‐CO₂) in low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), polypropylene (PP), ethylene‐ethylacrylate copolymer (EEA) and polystyrene (PS) were measured at temperatures from 150°C to 200°C and pressures up to 12 MPa by using the Magnetic Suspension Balance (MSB), a gravimetric technique for gas sorption measurements. The solubility of CO₂ in each polymer was expressed by Henry's constant. The interaction parameter between CO₂ and polymer could be obtained from the solubility data, and it was used to estimate the Pressure‐Volume‐Temperature relationship and the specific free volume of polymer/CO₂ mixtures. The diffusion coefficients were also measured by the MSB for each polymer. The resulting diffusion coefficients were correlated with the estimated free volume of polymer/CO₂ mixture. Combining Fujita's and Maeda and Paul's diffusion models, a model was newly developed in order to predict diffusion coefficients for the polymers studied. Polym. Eng. Sci. 44:1915–1924, 2004. © 2004 Society of Plastics Engineers.     

Solubility of H2S in n-hexadecane at elevated pressure

The solubility of H₂S in n-hexadecane has been determined at 50, 100 and 150°C at pressures up to 7.4 MPa. The results were correlated with the Peng-Robinson (1976) equation of state and Henry's constants were derived for comparison with low pressure data in the literature.     

Thermodynamic Models for Hydrogen-Containing Systems at Infinite Dilution

For a supercritical gas such as hydrogen, thermodynamic models for Henry's constant, partial molar volume, and partial molar enthalpy are sufficient in representing the thermodynamics of hydrogen-containing systems at infinite dilution. This work presents a generalized method and correlations for Henry's constant in binary systems containing hydrogen as a function of temperature. Experimental vapor–liquid equilibrium data were used to obtain this Henry's constant correlation with (i) three specific parameters, (ii) one specific parameter, and (iii) no specific parameter. These three Henry's constant correlations for hydrogen vary in the degrees of generalization and accuracy. A generalized corresponding states correlation for partial molar enthalpy of hydrogen in hydrocarbon systems at infinite dilution was derived from the newly developed Henry's constant correlation and from a correlation for infinite-dilution partial molar volumes of hydrogen available in the literature. Overall, this work provides the most extensive method for infinite-dilution thermodynamic properties of hydrogen-containing systems.     

Solubility of Natural Gas in Diesel Fuel

The solubility of commercially available natural gas in commercially available diesel fuel at room temperature and defined pressure is investigated experimentally. The gas phase is considered to be pure methane. The use of Henry's law to model the solubility is discussed. Solubility is given in terms of the mole fraction and the volumetric mass concentration of dissolved gas and the corresponding Henry's coefficients. The solubility is compared to that of pure methane in pure hexadecane, which is similar to diesel fuel with respect to the mean carbon number.     

Modeling nanoporosity development in polymer films for low‐k applications

The bubble growth dynamics of a polymer supersaturated with CO₂ have been modeled for micron‐size films after nucleation. The model equations are based on the shell model of Arefmanesh, Advani, and Michaelides in which a nucleated bubble is surrounded by a finite concentric shell of polymer supersaturated with gas. Bubbles grow by mass transfer of dissolved gas from this shell. The model is extended to allow for diffusion of dissolved gas out of the shell in addition to diffusion into the bubble. A parametric analysis is performed to examine the effects of film thickness, temperature, diffusivity at the T_g and Henry's law constant. POLYM. ENG. SCI., 45:640–651, 2005. © 2005 Society of Plastics Engineers     

Molecular Transport of Gases,Vapors, and Salt Solutions Through Polymer Membranes

Molecular transport of small molecules through polymer films has been widely studied over the past several years [1–8]. In most of these investigations it has been shown that the penetrant solubility and diffusion follow Henry's law and Fick's law, respectively, and that solubility (S), diffusion (D), and permeability coefficients (P) are independent of penetrant concentration. Several theories of diffusion, permeation, and solution have been developed to relate the experimental data to polymer film morphology, chemical structure, and other physical properties [9–14]. From a practical view point, the phenomenon of transport is very useful in the treatment of hazardous waste in landfill areas. In chemical industries, its importance lies in the separation of organic compounds. Additionally, membrane separation techniques have been used in such industrial applications as desalination of brine, salt manufacturing from seawater, oxygen-enriched air, etc. The pervaporation technique wherein the permeate is removed from a mixture at the opposite side of the membrane as a vapor is now very popular [15].