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Hydraulic fracturing is an effective technology for hydrocarbon extraction from unconventional shale and tight gas reservoirs. A potential risk of hydraulic fracturing is the upward migration of stray gas from the deep subsurface to shallow aquifers. The stray gas can dissolve in groundwater leading to chemical and biological reactions, which could negatively affect groundwater quality and contribute to atmospheric emissions. The knowledge of light hydrocarbon solubility in the aqueous environment is essential for the numerical modelling of flow and transport in the subsurface. Herein, we compiled a database containing 2129 experimental data of methane, ethane, and propane solubility in pure water and various electrolyte solutions over wide ranges of operating temperature and pressure. Two machine learning algorithms, namely regression tree (RT) and boosted regression tree (BRT) tuned with a Bayesian optimization algorithm (BO) were employed to determine the solubility of gases. The predictions were compared with the experimental data as well as four well-established thermodynamic models. Our analysis shows that the BRT-BO is sufficiently accurate, and the predicted values agree well with those obtained from the thermodynamic models. The coefficient of determination (R2) between experimental and predicted values is 0.99 and the mean squared error (MSE) is 9.97 × 10−8. The leverage statistical approach further confirmed the validity of the model developed. [ABSTRACT FROM AUTHOR]

The objective of this study is to assess the storage of acid gas, containing CO2 and H2S, in a depleted naturally fractured reservoir (NFR) using single matrix block (SMB) approach. The acid gas dissolution in oil is considered by Peng‐Robinson equation of state and compositional simulation. The PHREEQC package is used to determine acid gas solubility in formation brine. Three types of acid gases with different compositions are used for this study and their swelling behavior and miscibility in relation to the reservoir oil are analyzed. An SMB model, with a matrix block surrounded by fractures, is constructed, and validated for simulation of a real experiment. The simulation is conducted for synthetic and real reservoir fluids when the oil is in its residual saturation. A sensitivity analysis is performed to study the effects of key parameters, such as acid gas composition, reservoir pressure, permeability, porosity and matrix height on the storage capacity and oil recovery factor. The matrix has a volume of 27 m3 and about half of acid gas storage is achieved in the first 5 years while the simulations are run for 30 years. The results show that up to 90% of remained oil is recoverable, and more than 0.67 kmol of acid gas per cubic meter of matrix is stored whether matrix contains a real oil or a synthetic one. Higher storage is achieved for higher matrix porosities and heights and large H2S proportion in acid gas. In all cases about 10% of acid gas is trapped in water and the remaining 90% is dissolved in oil. The mineral trapping was more active in CO2‐rich acid gases. While about 10 kg of the matrix rock was dissolved in the acidic brine when the acid gas contained H2S, the amount of the dissolved minerals in acidic brine resulted from the injection of CO2‐rich acid gas was more than 16 kg. Finally, this study gives a comparative analysis of the storage performance of acid gas mixture and pure CO2. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Natural gas is easily soluble in oil-based muds (OBM), leading to complex flow behavior in wellbores, especially in horizontal wells. In this study, a new transient flow model considering wellbore-formation coupling and gas solubility on flow behavior is developed to simulate gas kicks during horizontal drilling with OBM. Furthermore, the effect of gas solubility on parameters such as bottom-hole pressure (BHP), gas void fraction and mixture velocity in the flow behavior is analyzed. Finally, several critical factors affecting flow behavior are investigated and compared to gas kicks in water-based muds (WBM) where the effect of solubility is neglected. The results show that the invading gas exists as dissolved gas in the OBM and as free gas in the WBM. Before the gas escapes from the OBM, the pit gain is zero and there is barely any change in the BHP, annulus return flow rate and mixture velocity, which means that detecting gas kicks through these warning signs can be challenging until they get very close to the surface and develop rapidly. However, in WBM drilling, these parameters change quickly with the increasing gas kick time. Additionally, for both cases, the longer the horizontal length and the greater reservoir permeability, the greater the decrease in BHP, and the shorter the time for gas to migrate from the bottom-hole to the wellhead. A larger flow rate contributes to a greater initial BHP and a lesser BHP reduction. This research is of value in characterizing gas kick behavior and identifying novel ways for early gas kick detection during horizontal drilling with OBM.

An innovative approach to controlling aircraft pitch is shown in this research. This approach is accomplished by adopting a proportionalintegral- derivative with filter (PID-F) mechanism. A novel metaheuristic approach that we propose is called the sinh cosh optimizer (SCHO), and it is intended to further optimize the settings of the PID-F controller that is used in the aircraft pitch control (APC) configuration. An in-depth comparison and contrast of the recommended method is carried out, and statistical and time domain assessments are utilized in order to ascertain the success of the method. When it comes to managing the APC system, the SCHO-based PID-F controller delivers superior performance compared to other modern and efficient PID controllers (salp swarm based PID, Harris hawks optimization based PID, grasshopper algorithm based PID, atom search optimization based PID, sine cosine algorithm based PID, and Henry gas solubility optimization based PID) that have been published in the literature. When compared to alternative approaches of regulating the APC system, the findings demonstrate that the way that was presented is among the most successful as better statistical (minimum of 0.0033, maximum of 0.0034, average of 0.0034 and standard deviation of 5.1151E-05) and transient response (overshoot of 0%, rise time of 0.0141 s, settling time of 0.0230 s, peak time of 0.0333 s and steady-state error of 0 %) values have been achieved. [ABSTRACT FROM AUTHOR]

The study of hydrate phase equilibrium is crucial for ensuring the safety of natural gas pipeline transportation and the process of hydrate recovery. While scientists typically focus on the chemical potential of hydrates, the role of gas solubility in hydrate phase equilibrium remains unclear, and this study fills this gap. This work investigated the solubility of gas at the equilibrium point of the hydrate phase through model calculations. Additionally, a new model of hydrate phase equilibrium is established based on the relationship between solubility. Firstly, a solubility model based on gas-liquid equilibrium theory showed higher prediction accuracy in comparison to the PR equation and Duan model and was then used to calculate gas solubility under hydrate phase equilibrium conditions. Afterwards, a novel model was developed to predict hydrate equilibrium state based on the relationship between gas solubility and hydrate phase equilibrium temperature, and it was further compared with the Chen-Guo model and CSMGem in terms of prediction accuracy under pure water and brine settings. The results showed: (a) The calculation deviation of the solubility model was 0.7-8.7% in pure water settings and 2.6-11.7% in brine settings; (b) A strong linear correlation between the phase equilibrium temperature of hydrates and gas solubility was also found; (c) This proposed model achieved over 10 times the accuracy of the Chen-Guo model and the CSMGem in predicting the phase equilibrium state of N2 and CO2 hydrates, and 3-10 times higher accuracy than that of the Chen-Guo model and CSMGem in brine. This work suggests that the gas solubility equilibrium theory can provide a more accurate prediction of hydrate states. [ABSTRACT FROM AUTHOR]

This study explored diethanolammonium chloride ([DEA]Cl) as a potential ionic liquid from low‐cost and commercial ones for gas separation. There are three kinds of functional sites in [DEA]Cl: acidic NH2+, hydrogen‐bond OH, and nucleophilic Cl−. The separation of NH3/N2/H2, SO2/CO2/N2, and H2S/CO2/CH4 was considered, because the three mixtures are extensively involved in many industrial processes. The experimental results demonstrated that [DEA]Cl exhibited excellent ability to separate the mixture of NH3/N2/H2. The [DEA]Cl also exhibited the proper capacity to separate SO2/CO2/N2, but the capacity of [DEA]Cl for the separation of H2S/CO2/CH4 was inferior. The theoretical calculations revealed that NH2+ and OH worked synergistically to contribute to the ability of [DEA]Cl for excellent separation of NH3 from NH3/N2/H2, with Cl− contributing to the proper separation of SO2 from SO2/CO2/N2. This study provides experimental and theoretical basis for the industrial application of [DEA]Cl in the area of gas separation. [ABSTRACT FROM AUTHOR]

The study of hydrate phase equilibrium is crucial for ensuring the safety of natural gas pipeline transportation and the process of hydrate recovery. While scientists typically focus on the chemical potential of hydrates, the role of gas solubility in hydrate phase equilibrium remains unclear, and this study fills this gap. This work investigated the solubility of gas at the equilibrium point of the hydrate phase through model calculations. Additionally, a new model of hydrate phase equilibrium is established based on the relationship between solubility. Firstly, a solubility model based on gas-liquid equilibrium theory showed higher prediction accuracy in comparison to the PR equation and Duan model and was then used to calculate gas solubility under hydrate phase equilibrium conditions. Afterwards, a novel model was developed to predict hydrate equilibrium state based on the relationship between gas solubility and hydrate phase equilibrium temperature, and it was further compared with the Chen–Guo model and CSMGem in terms of prediction accuracy under pure water and brine settings. The results showed: (a) The calculation deviation of the solubility model was 0.7–8.7% in pure water settings and 2.6–11.7% in brine settings; (b) A strong linear correlation between the phase equilibrium temperature of hydrates and gas solubility was also found; (c) This proposed model achieved over 10 times the accuracy of the Chen–Guo model and the CSMGem in predicting the phase equilibrium state of N2 and CO2 hydrates, and 3–10 times higher accuracy than that of the Chen–Guo model and CSMGem in brine. This work suggests that the gas solubility equilibrium theory can provide a more accurate prediction of hydrate states.

The noble gas argon has demonstrated biological activity that may prove useful as a medical intervention. Pharmacokinetics, the disposition of the drug molecule in the body through time, is fundamental necessary knowledge to drug discovery, development and even post-marketing. The fundamental measurement in pharmacokinetic studies is blood concentration of the molecule (and its metabolites) of interest. While a physiologically based model of argon pharmacokinetics has appeared in the literature, no experimental data have been published. Thus, argon pharmaceutical development requires measurement of argon solubility in blood. This paper reports on the development of a technique based on mass spectrometry for measuring argon solubility in liquids, including blood, to be further employed in pharmacokinetics testing of argon. Based on a prototype, results are reported from sensitivity experiments using ambient air, water and rabbit blood. The key takeaway is that the system was sensitive to argon during all of the testing. We believe the technique and prototype of the quadrupole mass spectrometer gas analyzer will be capable of inferring argon pharmacokinetics through the analysis of blood samples. [ABSTRACT FROM AUTHOR]

We present a novel molecular-based approach for the determination of the osmotic second virial coefficients of gaseous solutes in dilute binary solutions, according to a recently proposed molecular thermodynamic formalism of gas solubility [A. A. Chialvo, J. Chem. Phys. 148, 174502 (2018) and Fluid Phase Equilib. 472, 94 (2018)]. We discuss relevant solvation fundamentals and derive new expressions including (i) the relations among infinite-dilution solvation quantities leading to a novel self-consistent route to the calculation of the osmotic second virial coefficients, (ii) the new microstructural interpretation of the resulting osmotic second virial coefficients based on Kirkwood-Buff integrals, the unambiguous discrimination between short- and long-range contributions, and their limiting behavior as the solvent approaches its critical conditions, (iii) new rigorous expressions for the calculation of the osmotic second virial coefficients using standard reference thermodynamic data, and (iv) their underlying interdependence based on the constrained state variable invoked in the density expansion. We then invoke the proposed formalism to shed some light on the inaccuracies behind current calculations of osmotic second virial coefficients from molecular theory and simulation as well as macroscopic correlations. To advance the microscopic understanding and illustrate the functional relationship between the osmotic second virial coefficients, Henry's law constant, and the solute-solvent intermolecular asymmetry as a source of solution non-ideality, we use data for the microstructural and thermodynamic behavior of infinitely dilute Lennard-Jones systems obtained self-consistently via integral equations calculations. The newly derived relationships leading to the proposed formalism offer novel routes for the accurate determination of osmotic second virial coefficients of any type of solutes in dilute solutions regardless of the type and nature of the intermolecular interactions. However, for illustration purposes in the current work, we dealt with aqueous solutions of simple gases to exploit the abundance of standard thermodynamic data for the orthobaric Henry's law constant and solute distribution coefficients, as well as the availability of results from molecular-based calculations and macroscopic correlations. [ABSTRACT FROM AUTHOR]

A high-pressure experimental setup was used to obtain experimental data on the Hydrate Equilibrium (melting) Temperature (HET) of aqueous phases undersaturated with CO2, at different CO2 saturation levels and with different aqueous phase compositions (sodium chloride and sodium chloride/calcium chloride). This paper details the experimental equipment, methods, test fluids, and results. To study the phase equilibria of CO2-brine systems and further validate the results, hydrate dissociation conditions of CO2 in different concentrations of NaCl aqueous solutions were measured in the low-temperature region and over a wide range of pressure. Experimental results were compared against predictions of the simplified Cubic Plus Association Equation of State (sCPA-EoS) coupled with the van der Waals and Platteeuw solid solution theory. [ABSTRACT FROM AUTHOR]

• High precision of e-CPA in predicting noble gas solubility in solutions. • Salting-out effect investigation of electrolytes on noble gas solubility in water. • Enhancing the model accuracy based on noble gas dissolution behavior. • Effective modeling tool for achieving sustainable water resource management. Dissolved noble gases in water hold significant potential as tracers and precursors in various hydrogeological and geological applications, particularly in understanding surface water-groundwater interactions. These applications necessitate precise solubility predictions. Employing the fugacity-fugacity approach, our study models the solubilities of Neon, Argon, Krypton, Xenon, and Radon in both pure water and electrolyte solutions. Leveraging the Cubic-Plus-Association Equation of State, we achieve remarkable accuracy, with average deviations below 2.5 % for vapor pressure, liquid, and vapor-phase densities. Additionally, in water–gas binary systems, deviations in gas solubilities within pure water remain under 5.0 %. Extending our analysis to water–gas-salt ternary systems, our model demonstrates deviations smaller than 5.6 %. Alongside discussing the gas dissolution mechanism, this work emphasizes the adaptability of the model, informed by robust experimental and modeling data. The interpretations derived from modeling hydrogeological conditions are poised to enhance our understanding of hydrological processes, thereby assisting planners and water managers in achieving sustainable development and management of water resources. [ABSTRACT FROM AUTHOR]

We present an explicit molecular-based interpretation of the thermodynamic phase equilibrium underlying gas solubility in liquids, through rigorous links between the microstructure of the dilute systems and the relevant macroscopic quantities that characterize their solution thermodynamics. We apply the formal analysis to unravel and highlight the molecular-level nature of the approximations behind the widely used Krichevsky-Kasarnovsky [J. Am. Chem. Soc. 57, 2168 (1935)] and Krichevsky-Ilinskaya [Acta Physicochim. 20, 327 (1945)] equations for the modeling of gas solubility. Then, we implement a general molecular-based approach to gas solubility and illustrate it by studying Lennard-Jones binary systems whose microstructure and thermodynamic properties were consistently generated via integral equation calculations. Furthermore, guided by the molecular-based analysis, we propose a novel macroscopic modeling approach to gas solubility, emphasize some usually overlook modeling subtleties, and identify novel interdependences among relevant solubility quantities that can be used as either handy modeling constraints or tools for consistency tests. [ABSTRACT FROM AUTHOR]

Methods for predicting Henry's law constants Hij are important as experimental data are scarce. We introduce a new machine learning approach for such predictions: matrix completion methods (MCMs) and demonstrate its applicability using a data base that contains experimental Hij values for 101 solutes i and 247 solvents j at 298 K. Data on Hij are only available for 2661 systems i + j. These Hij are stored in a 101 × 247 matrix; the task of the MCM is to predict the missing entries. First, an entirely data‐driven MCM is presented. Its predictive performance, evaluated using leave‐one‐out analysis, is similar to that of the Predictive Soave‐Redlich‐Kwong equation‐of‐state (PSRK‐EoS), which, however, cannot be applied to all studied systems. Furthermore, a hybrid of MCM and PSRK‐EoS is developed in a Bayesian framework, which yields an unprecedented performance for the prediction of Hij of the studied data set. [ABSTRACT FROM AUTHOR]

In this study, the solubility of carbon dioxide gas in a series of 1-alkyl-4-methyl pyridinium and 1-alkyl-3-methylimidazolium-based ionic liquids with various anions, viz. thiocyanate ([SCN]−), chloride ([Cl]−) and bromide ([Br]−) was investigated using a quartz crystal microbalance at 298.15 K and pressures up to 0.4 MPa. CO2 solubility in the ionic liquids correlates well with the non-random two-liquid (NRTL) model. The results indicate that the cation alkyl chain length and the type of anion have the main effects on the solubility of carbon dioxide in ionic liquids. CO2 solubility in both 1-alkyl-4-methyl pyridinium and 1-alkyl-3-methylimidazolium-based ionic liquids increased with increasing alkyl chain length of the cation. Also, CO2 solubility was strongly dependent on the selection of the anion. CO2 solubility in both 1-alkyl-4-methyl pyridinium and 1-alkyl-3-methylimidazolium-based ionic liquids increased as follows: [SCN]− > [Cl]− > [Br]−. The solubility of CO2 in some of ionic liquids (ILs) was measured. CO2 solubility in ILs with different alkyl chain lengths in the cation increased with increasing alkyl chain length. Also, CO2 solubility increased with increasing anion basicity. [ABSTRACT FROM AUTHOR]

• Development of a novel EoS framework to model NOx solubility across a wide range. • High accuracy in predicting the solubility of NOx in various electrolyte solutions. • Understanding salting-out effects of electrolyte on NOx solubility. • Dissolution mechanism to accurately interpret phase behavior and model outcomes. Accurate prediction of the solubility of nitrogen oxides (NOx) in aqueous solutions is vital for effective NOx sequestration in flue gas treatment processes. In this study, we employed the electrolyte cubic plus associated Equation of State (EoS) framework to model the solubility of nitrous oxide and nitric oxide in aqueous solutions. The model parameters for pure substances were determined by regressing saturated vapor pressures and saturated gas and liquid densities. Additionally, temperature-dependent binary interaction parameters between water and gases (N 2 O and NO) were derived by fitting experimental solubility data in pure water. Similarly, interaction parameters between ions and N 2 O were determined by fitting experimental N 2 O solubility data in aqueous electrolyte solutions. The modeling results demonstrate that the proposed model can accurately predict the solubility of N 2 O and NO in aqueous solutions across a wide range of temperature, pressure, and salt concentrations, with average relative deviations in gas solubility of less than 4.5%. Furthermore, the salting-out effect and the adaptability of the model are comprehensively analyzed and discussed. [ABSTRACT FROM AUTHOR]

We probe the solute-induced perturbation of the mixed-solvent environment around simple gaseous solutes, identify the universal molecular-based signature for the underlying preferential solvation phenomenon, characterize the cosolvent effect on gas solubility as a manifestation of their preferential solvation in mixed-solvent environments, derive the explicit macroscopic-to-microscopic rigorous connections between the thermodynamic non-idealities and precisely defined fundamental structure making/breaking functions S α β. We illustrate the approach by analysing the solvation behavior of a series of non-polar gaseous solutes including noble gases and light hydrocarbons in polar mixed-solvent environments at ambient conditions. We link rigorously the thermodynamic response of a solute to the change of cosolvent environment to either a linear combination of fundamental structure making/breaking functions S α β or the universal preferential solvation function P S. Finally, we highlight their underlying connections with other thermodynamic preferential interaction parameters , and caution about the potential modeling risks when invoking the Kirkwood-Buff inversion protocol for the interpretation of preferential solvation. [ABSTRACT FROM AUTHOR]

• Novel method to determine vapor–liquid equilibrium of low volatility liquid or liquid mixtures and a compressed gas. • Mass Balance method based upon the measured density, system volume, and total mass of each component in the system. • Results compare favorably with "gold standard" precision microbalance method. • Compatible with a number of simultaneous thermophysical property measurements, e.g viscosity, speed of sound, spectroscopy, etc. Vapor-liquid equilibria measurements involving liquids with low volatility, such as many types of lubricants, ionic liquids, and various solvents are essential for process research and development in a wide variety of fields. State–of–the–art methods to measure these phase equilibria, e.g. thermogravimetric analysis or equilibrium cells, generally cannot be combined with instruments measuring thermophysical properties, e.g. density, transport properties, spectroscopic properties, etc. A novel approach was developed to measure simultaneously vapor–liquid equilibrium and thermophysical properties involving a single gas dissolved in one or more low-volatility liquids. The method is based upon a mass balance measuring liquid phase density, total masses in the system, and volumes. The governing equations of the novel approach are derived, and a detailed uncertainty analysis is presented. As an example, the solubility, density, and viscosity are measured with the new apparatus for a system of a non-volatile ionic liquid solvent saturated with the compressed hydrofluorocarbon gas, pentafluoroethane (R-125), at 25 °C and 75 °C and pressures to ∼ 3.1 MPa. The solubility data are validated by comparison to previously published literature data using a high precision gravimetric microbalance. The combination of vapor–liquid equilibria and thermophysical properties in a single experiment can significantly accelerate scientific and engineering studies. [ABSTRACT FROM AUTHOR]

We like to highlight the extension of COSMO-based models (COSMO RS-FV and COSMO SAC-FV) to the prediction of gas solubility in polymers, including polymerized ionic liquids (PILs) for the first time. To verify the applicability of COSMO-based models, the predicted values for gas solubility in both common polymers (CH4/N2 + PEG) and PILs (CO2 + P[MATMA][BF4]/P[VATMA][BF4]) were evaluated based on previous experimental data. It was confirmed that the COSMO-RS (Klamt) model performs better than the COSMO-SAC model for common polymers, whereas the COSMO-RS (ADF-Lei 2018) exhibits the best predictions for PILs. The moderately accurate predictions of COSMO-based models demonstrate the high potential for predicting gas solubility in polymers.

In this study, a thermodynamic model has been used to determine the solubility of carbon dioxide in an aqueous solution which is the combination of methyldiethanolamine (MDEA) and aminoethylethanolamine (AEEA). The physical equilibriums have been considered between the liquid and vapor phases and chemical equilibrium in the liquid phase. The SAFT-HR equation of state has been used to specify the fugacity coefficients of the components in the vapor phase. The liquid phase is considered as an electrolyte solution besides; the extended UNIQUAC has been applied to figure out the activity coefficients. The bubble point calculation has been used in this research. This method includes two main loops. Calculations related to chemical equilibrium are performed in the interior loop and the ones associated with phase equilibrium are done in the exterior loop. The solubility of carbon dioxide has been predicted by the optimized parameters of the model in the temperature range of 308.2–368.2 K. It has been calculated that the absolute average relative deviations of the model are 16.65, 19.33, 28.91 and 19.99 in the calculation of partial pressure of carbon dioxide in various loadings at the temperatures of 308.2, 328.2, 343.2 and 368.2 K. [ABSTRACT FROM AUTHOR]

In this study, the solubility of CO2 in DEA in the presence and absence of choline chloride was reported at different temperatures of 276.15, 298.15, 313.15, and 333.15 K, and pressure range of 4-15 bar. The solubility of CO2 was evaluated using the pressure decay method in a batch isochoric stirred absorption cell. Also, the design of experiments performed with Qualitek-4 software using the Taguchi method. Henry’s law constants at three different temperatures were calculated from the correlation of solubility data. Results showed that increasing the initial pressure and DEA concentration and also decreasing the temperature, increases the solubility of CO2. Optimum operating conditions to maximize the amount of CO2 absorption including the temperature of 276.15 K (minimum level), the initial pressure of 15 bar (maximum level), the concentration of DEA of 40 wt.% (maximum level), and the concentration of choline chloride of 5 wt.% (middle level). Also, Qualitek-4 software predicted the amount of solubility at the optimum conditions which was 7.5% different from the measured value.

Background: In order to counteract the economic and environmental issues presented by Ionic Liquids (ILs) for carbon capture in post-combustion processes, Deep eutectic solvents (DESs) are being researched as potential absorbents. These are an emerging class of ILs that have a strong contribution from hydrogen bonding and have shown promising trends in CO2 absorption in recent times. Methods: In this study, three hydrogen bond acceptors (HBA), along with 2-hydroxypropanoic acid (Lactic Acid (LA)) as the hydrogen bond donor (HBD), have been identified and analyzed as CO2 absorbents. Considering their structural properties, thermodynamic behavior, and experimental conditions as input parameters, a backpropagation neural network (BPNN) has been implemented to analyze and predict the extent of CO2 solubility within each of the DES mixtures. Significant Findings: BPNN successfully predicted trends in the solubility as a function of the alkyl chain length, temperature, and pressure. It was observed that the solubility of CO2 increased with increasing alkyl chain length and pressure but decreased with increasing values of temperature. DES is found to be more economical than other ionic liquid solvents used for CO2 absorption.

A high-pressure experimental setup was used to obtain experimental data on the Hydrate Equilibrium (melting) Temperature (HET) of aqueous phases undersaturated with CO2, at different CO2 saturation levels and with different aqueous phase compositions (sodium chloride and sodium chloride/calcium chloride). This paper details the experimental equipment, methods, test fluids, and results. To study the phase equilibria of CO2-brine systems and further validate the results, hydrate dissociation conditions of CO2 in different concentrations of NaCl aqueous solutions were measured in the low-temperature region and over a wide range of pressure. Experimental results were compared against predictions of the simplified Cubic Plus Association Equation of State (sCPA-EoS) coupled with the van der Waals and Platteeuw solid solution theory.

• Solubilities of CO 2 , CO, N 2 O, SO 2 , CH 4 and H 2 S gases in ionic liquids are correlated. • Machine learning models of MLP-ANN, Hybrid‐ANFIS, PSO‐ANFIS and CSA-LSSVM are implemented. • 3060 data points for 40 types of ILs were gathered. • Machine learning models can be used to estimate pollutant gas capture by ILs. • CSA-LSSVM model demonstrates the highest accuracy. Capture of air pollutant gases using novel and green solvents is obtaining widespread attention. Accurate estimation of this process is complex. We have estimated the absorption of CO 2 , CH 4 , H 2 S, N 2 O, SO 2 and CO gases in ionic liquids (ILs). We have applied Multilayer Perceptron-Artificial Neural Networks (MLP-ANN), Hybrid-Adaptive Neuro Fuzzy Inference System (Hybrid-ANFIS), Particle Swarm Optimization-Adaptive Neuro Fuzzy Inference System (PSO-ANFIS) and Coupled Simulated Annealing-Least Squares Support Vector Machine (CSA-LSSVM). We have gathered 3060 data of 72 IL-Gas mixtures for 40 types of ILs. The inputs of these models are: Temperature (T), pressure (P), IL molecular weight (Mw IL), IL critical temperature (T c , IL), IL critical pressure (P c , IL), IL acentric factor (ω IL), gas molecular weight (Mw gas), gas critical temperature (T c , gas), gas critical pressure (P c , gas), gas kinetic diameter (d) and the acentric factor (ω gas). The CSA-LSSVM model produces best estimation with an Average Absolute Relative Deviation (AARD) of 8.7%. The results suggest the solubilities of the gases in ILs are correlated with structural factors of ILs. Estimation of the equilibrium behaviors in ionic liquids is of importance in simulation and design of solvent-based pollutant gas capture processes. [Display omitted] [ABSTRACT FROM AUTHOR]

Dissolved oxygen is well known as an inhibitor in radical polymerization of vinyl monomer. Though the monomer solution is often saturated with argon or nitrogen to remove oxygen before polymer synthesis, there are few experimental data for the gas solubility. Thus, gas solubilities in solutions are reported for four binary systems. The solubilities of argon in styrene and nitrogen, oxygen or argon in methyl methacrylate (MMA) were measured at pressures up to 3.8 MPa, at 293, 303, 313 K. Gas solubilities at a given isotherm had linear pressure dependences, whereas Henry's constants decreased with increasing temperature. Argon solubilities in MMA were about 1.35 times larger than those in styrene. Nitrogen and oxygen solubilities in MMA were about 1.53 and 1.35 times larger than those for styrene. Experimental data could be correlated with the Peng–Robinson equation of state to within AARDs of 0.85% for argon in styrene and 1.31%, 1.53% and 0.81% for argon, nitrogen and oxygen solubilities in MMA, respectively. The data and the correlation allow analysis not only for Henry constants but also for gas concentration in monomer solution at given temperature and pressure. [ABSTRACT FROM AUTHOR]

Accurate calculation of light hydrocarbon solubilities in aqueous electrolyte solutions is critical for petroleum and geochemical applications. However, very few electrolyte Equations of State (e-EoS) have been used for calculation of light hydrocarbon solubilities. Thermodynamic calculation of gas (methane and ethane) solubilities in aqueous solutions of chloride salts are presented. This work introduces a new parameter estimation approach (which can predict well the liquid densities of aqueous solutions) for the electrolyte Cubic Plus Association EoS (e-CPA). The cation/anion–water interaction parameters are obtained from the regression of experimental mean ionic activity coefficients and liquid densities. The results show that the e-CPA with the new parameter estimation approach gives good agreements with the corresponding experimental data. The cation/anion–gas interaction parameters are obtained from the regression of experimental gas solubilities. The results show that the e-CPA with the new parameter estimation approach correlates the gas solubilities reasonably well. The gas dissolution mechanisms and salting effects are extensively analyzed and discussed for a deeper understanding of gas dissolution in aqueous electrolyte solutions. [ABSTRACT FROM AUTHOR]

This study assesses the feasibility of the Henry gas solubility optimization (HGSO), a recent novel metaheuristic algorithm, to achieve optimal parameters for a power system stabilizer (PSS) employed in a power system. To do so, the design problem was defined as an optimization problem and an integral of time-multiplied absolute error objective function was adopted. This objective function was minimized to tune the PSS parameters and improve the dynamic performance of the power system. The performance was evaluated using a single-machine infinite-bus system, and the obtained results were compared with atom search optimization and conventional based designed systems. The proposed HGSO approach for tuning PSS parameters has been shown to suppress electromechanical oscillations and provide a better statistical performance and convergence ratio. [ABSTRACT FROM AUTHOR]

In the offshore oil industry, Multipurpose Support Vessels with extensive diving capability are used for inspection, maintenance and repair of subsea pipelines. The diving industry has developed systemic safety checks and strict regulatory control after a number of fatal accidents in early years. However, accidents do continue to occur and, when involving divers in the water, are often fatal. Hydrogen sulphide (H2S), called 'sour gas' in an oil field, is produced by the action of anaerobic bacteria on sulphate containing organic matter. A highly toxic gas, it remains a constant danger for offshore oil industry workers who must remain vigilant. Crude oil and gas produced in these oilfields is called 'sour crude' and pipelines carry this crude with varying content of dissolved H2S to shore for processing. Divers are routinely called to attend to leaking pipelines and come in contact with this crude. Their hot water suits and umbilical lines are often covered with crude containing dissolved H2S. There is always a possibility that these may enter and contaminate the bell environment. Such a case leading to fatality is reported here. [ABSTRACT FROM AUTHOR]

We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines were narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Qbranch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule. [ABSTRACT FROM AUTHOR]

The catalytic activity of metal nanoparticles (NPs) supported on porous supports can be controlled by various factors, such as NPs size, shape, or dispersivity, as well as their interaction with the support or the properties of the support material itself. However, these intrinsic properties are not solely responsible for the catalytic behavior of the overall reaction system, as the local environment and surface coverage of the catalyst with reactants, products, intermediates and other invloved species often play a crucial role in catalytic processes as well. Their contribution can be particularly critical in liquid‐phase reactions with gaseous reactants that often suffer from low solubiltiy. One example is D‐glucose oxidation with molecular oxygen over gold nanoparticles supported on porous carbons. The possibility to promote oxygen delivery in such aqueous phase oxidation reactions via the immobilization of heterogenous catalysts onto the interface of perfluorocarbon emulsion droplets is reported here. Gold‐on‐carbon catalyst particles can stabilize perfluorocarbon droplets in the aqueous phase and the local concentration of the oxidant in the surroundings of the gold nanoparticles accelerates the rate‐limiting step of the reaction. Consequently, the reaction rate of a system with the optimal volume fraction of fluorocarbon is higher than a reference emulsion system without fluorocarbon, and the effect is observed even without additional oxygen supply. [ABSTRACT FROM AUTHOR]

In this study, we have examined the modeling of gas solubility in twenty room temperature ionic liquids based on the van der Waals and generic Redlich–Kwong equations of state and have also compared the obtained deviations with each other. The selected gases are carbon dioxide (R744) and 1,1,1,2-tetrafluoroethane (R134a). Experimental data represent a high correlation with the present equations of state. It is concluded that the absolute average deviation is less than 1% for each system, which illustrates the high accuracy and efficiency of the mentioned equations of state. Henry's law constant and some thermodynamic properties such as enthalpy and entropy in infinite dilution are calculated. [ABSTRACT FROM AUTHOR]

This study mathematically models the solubility of hydrogen sulfide in ten ionic liquids including 1-(2-hydroxyethyl)-3-imidazolium [Hoemim]+ with three different anions, 1-ethyl-3-methylimidazolium [emim]+ with two different anions, 1-hexyl-3-methylimidazolium [hmim]+ with two different anions, and 1-butyl-3-methylimidazolium [bmim]+ with three different anions. The modeling was performed by van der Waals (vdW) equation of state as a φ-φ approach in which the modified van der Waals–Berthelot mixing rule is used. The critical properties of ionic liquids have been estimated by a group of supplementary methods suggested by Valderrama and Robles, known as the modified Lyderson–Joback–Reid method. It is concluded that since the absolute average relative deviation is less than 1%, the developed model has a high accuracy. [ABSTRACT FROM AUTHOR]

Polymeric materials are widely used in hydrogen energy system such as FCEV and hydrogen refueling stations under high-pressure condition. The permeation property (coefficients of permeation, diffusion and solubility) of polymers under high-pressure hydrogen condition should be discussed as parameters to develop those devices. Also the property should be determined to understand influence of the compression by the pressure on polymer materials. A device which can measure gas permeation property of polymer materials accurately in equilibrium state under high-pressure environment is developed, and the reliability of the measurements is ensured. High-pressure hydrogen gas permeability characteristics up to 100 MPa are measured for high-density polyethylene. An advantage of the method is discussed comparing with the non-equilibrium state method, focusing on the hydrostatic pressure effect. Deterioration of hydrogen permeability is observed along with the decrease of diffusion coefficient, which is supposedly affected by hydrostatic compression effect with the increase of environment pressure. Image 1 • High pressure hydrogen gas permeation test device was developed. • Evaluation of polymer permeation in equilibrium state up to 100 MPa is possible. • Advantage of the method was compared with the non-equilibrium state method. • Hydrogen permeability deteriorates with the increase of gas pressure. • Hydrostatic compression effect can affect diffusion deterioration under higher pressure. [ABSTRACT FROM AUTHOR]

In this study the solubility of Hydrogen Sulfide (H2S) in four ionic liquids: 1-Ethyl-3-methylimidazoliom Hexafluorophosphate [Emim][PF6], 1-Ethyl-3-ethylimidazolium Tetrafluoroborate [Emim][BF4], 1-Ethyl-3-methylimidazolium Trifluromethanesulfonate [Emim][OTf] and 1-Ethyl-3-methylimidazolium Bistrifluoromethylsulfonilimide [Emim][NTf2] at temperature 343.15 K and relevant pressure has been simulated and the accuracy of obtained data compared to experimental ones. By comparing the radial distribution function of the [Emim]+-based ionic liquids with above-mentioned anions, it is found that the existence of H2S impacts the interactions between anion and cation and also the most appropriate anion among those, is [NTf2] which can properly solve H2S in its own. [ABSTRACT FROM AUTHOR]

The DNA motif discovery (MD) problem is the main challenge of genome biology, and its importance is directly proportional to increasing sequencing technologies. MD plays a vital role in the identification of transcription factor binding sites that help in learning the mechanisms for regulation of gene expression. Metaheuristic algorithms are promising techniques for eliciting motif from DNA genomic sequences, but often fail to demonstrate robust performance by overcoming the inherent challenges in complex gene sequences, making search environment extremely non-convex for optimization methods. This paper proposes a novel modified Henry gas solubility optimization (MHGSO) algorithm for motif discovery which elicits a functional motif in DNA genomic sequences. In our approach, a new stage that captures the main characteristics of the motifs in DNA sequences is proposed, and MHGSO imitates the motifs characteristics for accurate detection of target motif. The performance of the MHGSO algorithm is validated using both synthetic and real datasets. Results confirm the stability and superiority of the proposed algorithm compared to state-of-the-art algorithms including MEME, DREME, XXmotif, PMbPSO, and MACS. Based on several evaluation matrices, MHGSO outperforms the competitor techniques in terms of nucleotide-level correlation coefficient, recall, precision, F-score, Cohen's Kappa, and statistical validation measures. [ABSTRACT FROM AUTHOR]

In this study, we investigate the secondary sorption in an air-entrained Portland cement mortar that is purged with different gases— CO 2 , CH 4 , or N 2 . By altering the gas phase present in the void space, we are able to evaluate how gas solubility influences the secondary sorption. The rate of water sorption in the presence of different gases in the entrained voids was captured using successive 30 min X-ray micro-computed tomography scans for 24 h after water-specimen contact. The results show the higher the solubility of the gas, the faster the mortar reaches saturation. The air voids in the CO 2 -purged specimen begin to absorb water within 30 min and reach a critical degree of saturation within hours, while the air voids of N 2 and CH 4 -purged specimens show a significantly slower water absorption over 24 h. The high solubility of CO 2 was found to alter the X-ray mass attenuation value of the water as the water becomes CO 2 saturated. These tests reveal the gas type present in the void space significantly influences secondary sorption of Portland cement mortars. The findings of this study have implications on predicting mass transport in cement-based materials used in below ground carbon sequestration structures. [ABSTRACT FROM AUTHOR]

We present a new strategy to estimate the temperature‐dependent vapor–liquid equilibria and solvation free energies of dilute neutral molecules based on only their estimated solvation energy and enthalpy at 298 K. These two pieces of information coupled with matching conditions between the functional forms developed by Japas and Levelt Sengers for near critical conditions and by Harvey for low and moderate temperature conditions allow the fitting of a piecewise function that predicts the temperature‐dependent solvation energy for dilute solutes up to the critical temperature of the solvent. If the Abraham and Mintz parameters for the solvent and solute are available or can be estimated from group contributions, this method requires no experimental data and can still provide accurate estimates with an error of about 1.6 kJ/mol. This strategy, which requires minimal computational resources, is shown to compare well with other methods of temperature‐dependent solvation free energy prediction. [ABSTRACT FROM AUTHOR]

We describe a field study where tracer gas was injected into a subsurface cavity created by a small chemical explosion beneath the water table. The main objective of the study is to compare the migration of sulfur hexafluoride (SF6) and xenon (Xe) through an explosion‐generated fracture network and to study the influence of ground water on gas transport. A mixture of tracer gases (50% of SF6 and 50% of Xe) was injected on 31 October 2018 and gas sampling continued until 8 November 2018. We observe similar trends in SF6 and Xe concentrations at four ground surface sampling sites. The changes in the SF6/Xe ratios with time show that more SF6 than Xe is observed during the barometric pressure lows when the absolute measured concentrations are highest. Conversely, the ratio SF6/Xe is less than 1 during the high‐pressure intervals when absolute measured concentrations are low. The results of the experiment suggest that during barometric pressure lows the tracer is migrating to the surface primarily by advective gas phase transport, whereas during barometric pressure highs, advection is suppressed and near‐surface evaporation of interstitial pore fluid with tracer dissolved in it becomes more important. Thus, the results of the experiment show that the gas concentrations at the surface are controlled by the combined effects of the gas dissolution into pore water and the barometric pressure fluctuations. Plain Language Summary: We injected a mixture of two tracer gases (Xe and SF6) into an underground explosion‐generated cavity and monitored their concentrations at the surface. The arrival times at the surface were similar for both gases. The observed ratios of SF6 and Xe concentrations typically varied by about a factor of 2 over a million‐fold range of measured concentrations and correlate with the absolute gas concentrations. Our results indicate that the breakthrough times and the concentrations of the tracer gases are affected by fluctuations of the barometric pressure. Key Points: We conducted a unique field‐scale experiment to compare the migration of two tracer gases, SF6 and Xe, through fracture networks, generated by chemical explosionsThe observed arrival times were similar for both gases; SF6 concentrations usually tracked Xe concentrations within a factor of 2 over concentration variations of 6 orders of magnitudeThe observed surface concentrations are affected by the fluctuations in the atmospheric pressure and by gas solubilities in pore water [ABSTRACT FROM AUTHOR]

A review of the theoretical data accumulated for the last decade on the diffusion kinetics of the stage of homogeneous nucleation of liquid droplets and gas bubbles in multicomponent systems has been presented. In addition to the previously known results, the review contains new relations and discussions that represent the further development of own studies. Thermodynamic expressions that relate the composition of critical droplets and bubbles occurring at unstable equilibrium with metastable multicomponent systems to the sizes of new-phase particles and degrees of supersaturation in the systems have been discussed. The dynamics of the growth of individual multicomponent supercritical droplets and bubbles at the stage of nucleation has been described at arbitrary values of vapor supersaturation for droplets and gas solubility in solutions for bubbles. The kinetics of the nucleation stage has been considered for ensembles of droplets and bubbles within the framework of the mean-field description of supersaturations and the excluded-volume approach. A relation has been shown between the excluded-volume approach to the description of the nucleation stage and the Kolmogorov crystallization theory. [ABSTRACT FROM AUTHOR]

Monodisperse lipid-coated microbubbles are a promising avenue to unlock the full potential of ultrasound contrast agents for medical diagnosis and therapy. However, their formation by microfluidic flow-focusing is non-trivial. The lipid monolayer shell around the freshly formed bubbles is initially loosely packed, resulting in gas exchange between bubbles through Ostwald ripening, eventually leading to the formation of large, potentially thrombogenic, foam bubbles. Here, we show that by formulating a gas mixture of a low- and a high-aqueous solubility gas, a microbubble suspension can be formed that is not only monodisperse and highly stable, but it can also be synthesized without foam bubble formation at clinically relevant concentrations. The optimal gas volume fraction and resulting gas composition of the stable bubbles are modeled and were found to be in excellent agreement with the experimental data. This physics approach to an interfacial chemistry problem therefore opens a route to bedside production of stable, safe, and readily injectable monodisperse bubbles for medical applications. [ABSTRACT FROM AUTHOR]

Reservoir fluid properties such as oil formation volume factor and solution gas oil ratio are of primary importance in reservoir engineering computations such as material balance calculation, while viscosity of crude oil and density required for controlling the oil’s flow through porous media and pipes and play an essential role in production engineering and in well problem analysis. This study evaluates all available published oil formation volume factor and gas oil ratio empirical correlations against a set of Yemeni PVT data. The study presents new tuned empirical correlations for Yemeni crude oils for oil formation volume factor and solution gas oil ratio at bubble point pressure based on huge Yemeni data sets. Excel program techniques such as solver function are also used for predicting oil formation volume factor and solution gas oil ratio at bubble point pressure. To compare the performance and accuracy of the new reservoir fluid properties correlations, statistical error analysis is performed. The statistical analysis results indicate that, the new tuned oil formation volume factor and solution gas oil ratio correlations outperforms the most common empirical correlations with least average absolute error, least standard deviation and highest correlation coefficient. [ABSTRACT FROM AUTHOR]

Poly (4-methyl-2-pentyne) (PMPentyne) and poly (4-methyl-1-pentene) (PMPentene) as membrane gas-separating media were studied with a combination of experimental and theoretical approaches. Experimental approaches included the permeability measurements for C1–C4 alkanes in linear heating mode (for PMPentyne) and under isothermal conditions (for PMPentene), and diffusivity evaluation by a differential method for PMPentene. Theoretical approaches included the 'hard-spheres' theory for calculation of gas solubility in PMPentyne and gas transport theory for two-phase systems for the estimation of the amorphous and crystalline phases contribution in PMPentene. Correlation analysis was used for any type of gas transfer parameter calculation where experimental data were lacking. These combinations of methods allowed obtaining the whole set of parameters for any gas–polymer pairing and explained the butane-selective properties revealed in PMPentyne (C1 < C2 < C3 < C4) and methane-selective properties of PMPentene (C1 > C2 > C3 > C4). [ABSTRACT FROM AUTHOR]

A popular and desirable function of superhydrophobic coatings is their remarkable ability to retain an entrapped layer of air, called a plastron, when submerged underwater. The drawback is that the air layer is short‐lived due to solvation into the surrounding liquid. While manipulating the solubility of gases using temperature is a possible approach, it generally requires inefficiently heating large volumes of water. Following the demonstrated ability to maintain air bubbles on superhydrophobic surfaces for drag reduction, this article introduces a novel method of extracting gas from water to replenish and stabilize the plastron on superhydrophobic surfaces for sustained antifouling abilities. This method involves locally heating the liquid surrounding a superhydrophobic coating, reducing gas solubility, and causing the gas to nucleate at the liquid–air interface. The approach requires a relatively low energy input, due to the small volume of locally heated water. With a constant supply of equilibrated water and minimal energy input, the plastron can survive indefinitely without the need for a mechanical delivery of air. The thermoregenerating superhydrophobic samples were shown to exhibit excellent antifouling behavior and inhibited diatom attachment over a period of 5 days. [ABSTRACT FROM AUTHOR]

Mixed matrix membranes (MMMs) are seen as promising candidates to overcome the fundamental limit of polymeric membranes, known as the so-called Robeson upper bound, which defines the best compromise between permeability and selectivity of neat polymeric membranes. To overcome this limit, the permeability of the filler particles in the MMM must be carefully matched with that of the polymer matrix. The present work shows that it is not sufficient to match only the permeability of the polymer and the dispersed phase, but that one should consider also the individual contributions of the diffusivity and the solubility of the gas in both components. Here we compare the gas transport performance of two different MMMs, containing the metal–organic framework CuNi-MOF in the rubbery Pebax®1657 and in the glassy poly(ether-ether-ketone) with cardo moiety, PEEK-WC. The chemical and structural properties of MMMs were investigated by means of FT-IR spectroscopy, scanning electron microscopy and EDX analysis. The influence of MOF on the mechanical and thermal properties of both polymers was investigated by tensile tests and differential scanning calorimetry, respectively. The MOF loading in Pebax®1657 increased the ideal H2/N2 selectivity from 6 to 8 thanks to an increased H2 permeability. In general, the MOF had little effect on the Pebax®165 membranes because an increase in gas solubility was neutralized by an equivalent decrease in effective diffusivity. Instead, the addition of MOF to PEEK-WC increases the ideal CO2/CH4 selectivity from 30 to ~48 thanks to an increased CO2 permeability (from 6 to 48 Barrer). The increase in CO2 permeability and CO2/CH4 selectivity is maintained under mixed gas conditions. [ABSTRACT FROM AUTHOR]

It is significant for the environment that molecular oxygen replaces conventional heavy metal-containing or toxic oxidants to participate in oxidation reactions. However, the involved gas–oil–solid multiphase catalytic reactions usually show low reaction efficiency due to the low solubility of gas in oil. Herein, an organic–inorganic hybrid with certain interfacial activity was synthesized by using an alkoxysilane covalent modified POM. Such a hybrid POM has surface activity and can be adsorbed at the gas–liquid interface, and allows direct contact between the gas, oil and catalyst at the interface. The performance of the foam system is superior to that of the conventional multiphase catalytic reaction at room temperature. In addition, no solvent was required for the reaction. The catalyst can be recovered by centrifugation after the reaction. [ABSTRACT FROM AUTHOR]

The micronano bubble water system (MNBW) generated by a micronano bubble generator (MNBG) has the superior oxidation properties and can improve gas solubility. In the study, a new wet recycling process based on MNBW is proposed to simultaneously remove nitric oxide (NO) and sulfur dioxide (SO2). The important experimental parameters such as initial water pH, initial water temperature, NO and SO2 concentrations, and the presence of oxygen (O2) were investigated to explore the feasibility of desulfurization and denitration with MNBW. The experimental results showed that decreasing initial water pH or increasing initial water temperature and NO and SO2 concentrations were not conducive to the removal of NO or SO2. O2 could promote the removal of NO, but it had no effect on SO2 removal. In addition, SO2 removal efficiency always remained high and did not change obviously during the experimental period. However, NO removal efficiency gradually decreased in the first 50 min and then became stable. [ABSTRACT FROM AUTHOR]

• Short-cut method for assessing solvents for gas cleaning by reactive absorption. • Simple and well-behaved empirical model for gas solubility with physical background. • Methods and models easy to implement in MS Excel. A new short-cut method (NoVa) for assessing solvents for gas cleaning by reactive absorption is presented. It considers the absorption / desorption cycle using the assumption of infinite number of stages in both columns. For a given feed and removal rate, the method yields an estimate for the specific regeneration energy q as a function of the solvent circulation rate L / G. The sole solvent-dependent input consists of two correlations describing the gas solubility at absorber and desorber conditions and estimates of caloric properties. Furthermore, a simple equation (SolSOFT) for correlating the gas solubility as a function of the gas loading of the solvent is presented. A theoretical analysis of the process reveals general properties of the dependency of q on L / G. The NoVa method is described and tested using amine-based solvents for post combustion carbon capture as examples. [ABSTRACT FROM AUTHOR]

Thermophilic mixed culture fermentation (TMCF) has advantages such as high substrate degradation rate (e.g. 0.5 d−1 of 60 °C vs 0.2 d−1 of 35 °C), hydrogen and methane yields (e.g. 3–4 mol-H2/mol-glucose at 70 °C vs 1–2 mol-H2/mol-glucose at 35 °C) and low gas solubility (e.g. H2 decrease 10% and CH4 decrease 30%) for the treatment of hot wastewater. However, the low biomass concentration, complexity of metabolites and high-running cost still limit its application to some extent. Here, the typical metabolic reactions in this process are briefly summarized. Then, the recent advances in alkali TMCF, anaerobic membrane bioreactor, individual metabolite production, thermophilic microbial fuel cells and thermophilic syngas fermentation are reviewed. The following separation processes of biogas upgrading, gas stripping and electrodialysis are also reviewed to separate and purify the metabolites in TMCF. Lastly, to meet the demands of better overall performance and lower-running cost, the prospects in the fields of direct interspecies electron transfer, medium chain fatty acids production and energy cost reduction are highlighted, but new strategies in TMCF still need to be developed in the future. [ABSTRACT FROM AUTHOR]