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Triethylene glycol (TEG) is widely used in the gas dehydration process. While absorbing water from the gas, some hydrocarbons may also be absorbed. Knowledge of hydrocarbon solubility in TEG is nec...

Energy shortage and environmental pollution are among the most serious challenges facing mankind. The utilization of efficient and green solvents has great urgency, if true action is to be taken to alleviate these issues. The Deep Eutectic Solvents (DESs) were recently introduced as sustainable solvents with special characteristics. These novel solvents have very low vapor pressures and can be “designed” for desired properties through the engineered selection of appropriate hydrogen-bond donors and acceptors. Research is necessary to investigate the feasibility of applying DESs in various industrial applications, including absorption refrigeration systems. Since the coefficient of performance (COP) and the exergetic coefficient of performance (ECOP) of an absorption refrigeration system depend highly on the properties of the absorbent and refrigerant, selecting a proper DES with particular attention to its physical properties, can dramatically affect its efficiency. In this study, three DESs were investigated as potential absorbents, consisting of Reline (1 Choline chloride + 2 urea), Ethaline (1 Choline chloride + 2 ethylene glycol) and Glyceline (1 Choline chloride + 2 glycerol), with ammonia as the refrigerant. A modified SRK-NRTL model was used to estimate the physical and thermodynamic properties of the DESs and their mixtures with ammonia. The COPs and ECOPs of the absorption refrigeration cycles were calculated within wide ranges of absorber and regenerator temperatures. The results were compared to literature systems, including ammonia/water and ammonia/ionic liquids cycles. The performances based on energy and exergy analyses showed that ammonia/DES working fluids have the potential to be used in such cycles.

Cyclohexanone is largely generated in the direct or indirect conversion of lignin-derived bio-oils. Hence, the upgrading of cyclohexanone, i.e. deoxygenation in the presence of hydrogen is of great interest. In this regard, two nickel-molybdenum catalysts on alumina support were investigated in the temperatures up to 400 °C and pressures up to 15 bar. High activity, selectivity, and yield were achieved by utilizing these catalysts at the studied condition. The main products of the upgrading of cyclohexanone were C6, C7, and C12 cyclic, aromatic, and bicyclic including cyclohexane, cyclohexene, benzene, and cyclohexylbenzene. The results of the present study imply that these catalysts are beneficial in producing hydrocarbon-rich products from cyclohexanone and lignin-derived bio-oils. Based on the achievements of the present study, the nickel-molybdenum catalyst composed of 1.14 wt% nickel and 14.27 wt% molybdenum showed about 87%, 100%, and 116% conversion of cyclohexanone, total hydrocarbon selectivity, and total hydrocarbon yield, respectively. The optimum condition for obtaining such results was at 400 °C and 8 bar.

Among the different thermophysical properties of significant importance in the study of transport phenomena, viscosity has long defied attempts at presenting a unified model applicable to both pure compounds and binary mixtures within extended temperature and composition ranges. Similar to the role that ln(Psat.)–T−1 profiles play in linearizing vapor pressure data, here it is contended for the first time that it is highly beneficial to study viscosity in the space, as opposed to the commonly used logarithmic space. Within this framework, the groundbreaking Lewis–Squires model is modified and extended to mixtures by studying 184 binary systems with 89 distinct ILs and 17 polar and nonpolar solutes. The dataset covers a total of 1104 isotherms with 10 909 data points, having quite an extensive range of viscosities, from 0.447 to 113 733 (mPa s). Breaking a highly regarded convention upheld for decades, the proposed model does not stipulate the availability of pure state viscosity and/or volumetric data over the whole temperature range, which acts as a bottleneck for the current literature models that have all been cast in the same mold inspired by thermodynamic mixing rules. In practice, without utilizing any volumetric properties, a single pure solvent viscosity datum at any reference temperature is the only requirement in the interpolative mode, which is complemented by the binary viscosity data at the reference isotherm of choice in the extrapolative mode of the proposed model that is concurrently applicable to both pure components and binary mixtures. An AARD of 2.82% was obtained in estimating the binary viscosity data using the new algorithm, while deviations of 13.58%, 6.79%, 6.17%, and 3.41% were obtained for the Grunberg and Nissan, Fang and He, Jouyban–Acree, and Eyring-MTSM models, respectively. Moreover, for extrapolation of the binary data measured at room temperature, a capability exclusive to the proposed model, an overall AARD of 5.66% was obtained for the mixtures of interest. With significant inherent flexibility, the new methodology could also be employed to represent the uncommon composition dependence of certain IL systems exhibiting multiple local extrema, with AARDs close to half of those of the current models.

In this work, the selective separation of toluene from mixtures of toluene + heptane or toluene + hexane was investigated using the newly emerging family of solvents, namely, deep eutectic solvents...

The spent bleaching clay (SBC) from the edible oil refining industries contains different types of contaminants, including fatty acids and trace amounts of heavy metals and hazardous materials. Therefore, the conventional procedure of landfilling of SBC is not safe for the environment. Because of this, researchers have been trying to find alternative routes, such as novel processes to regenerate the clay and reuse it. The large amounts of oil remaining in SBC justifies the investigation of in-situ transesterification of the oil to biodiesel. In this study, clays that have been de-oiled by in-situ transesterification at various operating conditions are investigated for their final regenerated bleaching capacity. The different in-situ operating parameters considered are: the choice between two different alkali catalysts, catalyst/SBC ratio, ethanol/SBC ratio, temperature, and reaction time. With 60 different experiments and using the method of experimental design, the optimum operating parameters were determined and presented for achieving maximum bleaching capacity of the regenerated clay. The suggested conditions were then confirmed experimentally. Results showed that the maximum bleaching capacity at these optimum conditions was 17.03%.

Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. In this study, the viscosity behavior of two mixtures of Ethaline (1 ChCl:2 ethylene glycol) with either methanol or ethanol were investigated over the temperature range of 283.15–333.15 K at atmospheric pressure. The measured viscosities of neat Ethaline, methanol, and ethanol showed reliable agreement with the corresponding reported literature values. The mixture viscosities were modeled by an Arrhenius-like model to determine the behavior of viscosity with respect to temperature. The data were also modeled by the four well-known mixture viscosity models of Grunberg–Nissan, Jouyban–Acree, McAllister, and Preferential Solvation. All of the model results were reliable, with the Jouyban–Acree and Preferential Solvation models showing the most accurate agreement with the experimental measurements. The Jones–Dole viscosity model was also investigated for the measured viscosities, and by analyzing the results of this model, strong interactions among Ethaline and the alcohol molecules were proposed for both systems. As a final analysis, viscosity deviations of the investigated systems were calculated to study the deviations of the viscosity behaviors with respect to ideal behavior. Both systems showed negative viscosity deviations at all of the investigated temperatures, with the negative values tending towards zero, and hence more ideal behavior, with increasing temperatures. Moreover, in order to correlate the calculated viscosity deviations, the Redlich–Kister model was successfully used for both systems and at each investigated temperature. publishersversion published

The spent bleaching clays (SBC) of vegetable oil refining plants have residual vegetable oil contents ranging from 17 to 40 wt%. The common worldwide practice of landfilling such spent clays imposes inevitable environmental hazards. The extraction of oil from a spent clay will not only alleviate this problem, but can also provide an oil source for processes, such as transesterification for the production of alcohol-esters. In-situ transesterification of the residual oil within SBC is an even more attractive idea, as it can eliminate the extraction step from the process. In this study, in-situ transesterification on the spent bleaching clay of a local vegetable oil plant was investigated experimentally. Furthermore, optimum operating conditions were determined for a number of parameters influencing the conversions, including reaction temperature, ethanol-to-SBC ratio, alkali catalyst type, and catalyst-to-SBC mass ratio. The experiments were designed by the response surface method based on the central composite approach (RSM-CCD model). The results were analyzed using the analysis of variance method (ANOVA) to investigate the effect of the parameters on the efficiencies of the biodiesel produced and the oil removed from the initial SBC. Within the ranges investigated, the maximum conversion to ethyl-ester was 72.90% at the optimum conditions of a reaction temperature of 73.2 °C, reaction time of 4.5 h, ethanol/SBC ratio of 4.2 ml/g, while using NaOH alkali catalyst with a catalyst-to-SBC mass ratio of 4.33%.

ERC-2016-CoG 725,034 UID/QUI/50006/2019 Deep eutectic solvents (DESs) are newly introduced green solvents that have attracted much attention regarding fundamentals and applications. Of the problems along the way of replacing a common solvent by a DES, is the lack of information on the thermophysical properties of DESs. This is even more accentuated by considering the dramatically growing number of DESs, being made by the combination of vast numbers of the constituting substances, and at their various molar ratios. The speed of sound is among the properties that can be used to estimate other important thermodynamic properties. In this work, a global and accurate model is proposed and used to estimate the speed of sound in 39 different DESs. This is the first general speed of sound model for DESs. The model does not require any thermodynamic properties other than the critical properties of the DESs, which are themselves calculated by group contribution methods, and in doing so, make the proposed method entirely independent of any experimental data as input. The results indicated that the average absolute relative deviation percentages (AARD%) of this model for 420 experimental data is only 5.4%. Accordingly, based on the achieved results, the proposed model can be used to predict the speeds of sound of DESs. publishersversion published

Deep Eutectic Solvents are complex solvents whose properties are challenging to understand and to model. In this study, the Prigogine–Flory–Patterson (PFP) theory was used, for the first time in literature, to estimate excess molar volumes of different systems consisting of Deep Eutectic Solvents (DESs). Twelve different systems, consisting of Ethaline + DMSO, Ethaline + water, Reline + water, Reline + methanol, Reline + ethanol, Glycine + water, Glycine + methanol, Glycine + ethanol, Glycine + isopropanol, Maline + water, Tegaline + water, and Glucoline + water were investigated in the full range of concentrations and within wide ranges of temperature, at atmospheric pressure. Excess molar volume is a complicated thermodynamic property because it depends not only on the shape, size, and chemical nature of each pure component in the mixture, but also on all of the binary and higher order interactions of the components in the mixture. The Prigogine–Flory–Patterson theory is one of the very few theoretical models for estimating excess molar volume. Because of the thermodynamic background of the PFP theory, which divides the excess molar volume into three different molecular interaction contributions, the results of this model in mixtures involving DESs can be valuable for a rough interpretation of the molecular interactions of such complex mixtures at a microscopic scale. In order to avoid the correlative aspect of the PFP theory, a generalized relation was proposed for the interaction parameter of the theory covering all temperatures. The resulting model, with a total AARD% of 14.6% and agreement between the predicted trends and the corresponding experimental trends, indicated the capability and suitability of the PFP theory in estimating excess molar volumes of such complex and non-ideal mixtures consisting of DESs.

Deep eutectic solvents (DESs), with their attractive properties, are currently of great interest. Introducing new kinds of eutectic solvents with different components as their hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA), and investigating the (thermo-) physical properties of the new DESs can play an important role in promoting future research and use of such mixtures. In this study, we investigate the feasibility of the formation of new kinds of eutectic solvents based on the sodium halide salts as the hydrogen bond acceptors with ethylene glycol as the hydrogen bond donor. Different molar fractions of HBD/HBA were investigated. The results indicated that sodium fluoride does not form a DES throughout the whole concentration range investigated, while sodium chloride, sodium bromide, and sodium iodide do form eutectic mixtures at certain molar ratios. Differential scanning analysis was performed on the resulting eutectic solvents to measure the glass transition temperature. Other physical properties of the proposed DESs, namely density, viscosity, refractive index, and electric conductivity were also measured within the temperature range of 293–333 K. Furthermore, the effect of water in aqueous mixtures of the proposed DESs was investigated, with molar fractions of water ranging from 0.1 to 0.9. Based on the calculations of excess molar volume, the effect of water in the mixtures was investigated. Over the whole range of water concentrations in the mixture, the excess molar volumes had negative values, indicating intensive hydrogen-bonding between unlike molecules in the mixture and/or a void filling mechanism by the smaller molecules.

Deep Eutectic Solvents (DESs) have been introduced recently as a new generation of green solvents. DESs have great potential to be used in different fields and applications, and so, it is important to have information on the properties of DESs and their mixtures. Up to now, the volumetric properties of only aqueous mixtures of DESs have been investigated. In this study, we measured the densities of pseudo-binary mixtures of methanol and choline chloride + urea (1:2) (reline) at atmospheric pressure over the temperature range of 293.15–323.15 K. Based on the measured density data, excess molar volumes of the mixtures were calculated. All of the excess molar volumes had negative values, which show the stronger solvation interactions of the mixture molecules compared to the interactions within pure reline or methanol. Furthermore, the volumetric properties of partial molar volume, excess partial molar volume, partial molar volume at infinite dilution, excess partial molar volume at infinite dilution, and isobaric volume expansion were calculated. By comparing the excess partial molar volumes at infinite dilution of reline and methanol, it is concluded that each prefers to be surrounded by the other, and this tendency is stronger for reline molecules.

In this study, the deep eutectic solvent of choline chloride/urea, also known as Reline, was synthesized. Mixtures of Reline with ethanol were prepared covering the entire concentration range, and their densities were determined experimentally. Together with pure Reline and pure ethanol, this made a total of eleven systems, whose densities were measured over the temperature range of 293.15–333.15 K at pressure of 100 kPa. The volumetric properties of interest in the calculation of other derivative thermodynamic properties were determined for all of the investigated mixtures and temperatures. This included the correlation of density to temperature, as well as the excess molar volumes, partial molar volumes, partial molar volumes at infinite dilution, excess partial molar volumes, excess partial molar volumes at infinite dilution, and isobaric volume expansions. The excess molar volumes had negative values at all concentrations and temperatures. This led us to propose a possible molecular arrangement of the hydrogen bond network, placing Reline mainly in central positions, with the preference to be surrounded by ethanol molecules.

Deep eutectic solvents (DESs) make up a most-recent category of ‘green’ solvents with a potentially promising future. Insignificant vapor pressure, biodegradability, low cost, task-specific engineering, and high absorption for gases such as CO2 are the most important characteristics of most DESs. To apply DESs in various industries, knowledge of their physical properties is vital. Since the viscosity of a DES is a strong function of temperature, as well as the ratio of the hydrogen bond donating and accepting components, to estimate the viscosity behavior, a model based on sound theory is proposed in this study, i.e., the free volume theory. Since DESs are strongly associating components, this theory is enriched by using associating equations of state, namely CPA and PC-SAFT. In this study, a large density and viscosity databank of 27 DESs of different nature, also with varying molar ratios of the hydrogen bond donor and acceptor, were used to propose the model. In this way, a global model is presented for the first time to estimate the viscosities of DESs. The pseudo-component approach, with a 2B association scheme, was considered for the DESs. Both the CPA and the PC-SAFT EoSs, coupled with the free volume theory, showed reliable results, with average AARD% values in viscosity for all of the investigated DESs equal to 2.7% and 2.7%, respectively. Furthermore, both models reliably showed the trend of nearly logarithmic increase in DES viscosity with decreasing temperature. Also, both models accurately estimated the viscosity behavior of the DESs by not only changing the molecular nature of the hydrogen bond donor with a fixed hydrogen bond acceptor, but also at all of the various molar ratios investigated.

In this study, a new correlation is proposed for estimating 1-alkyl-3-methylimidazolium ionic liquid (IL) viscosities at different temperatures and atmospheric pressure. Since ILs are rather novel,...

In this study, the aqueous mixture viscosities of two phenolic DESs, consisting of (1 ChCl: 3 phenol) and (1 ChCl: 4 phenol), were measured at atmospheric pressure over the temperature range of 293.15 - 333.15 K. According to the measured data, the values of viscosity deviations for the investigated aqueous systems were calculated to indicate deviating viscosity behavior with respect to ideality. Both aqueous systems showed negative viscosity deviations over the entire composition range and at all of the investigated temperatures. The Redlich-Kister model was applied to estimate the viscosity deviations of both aqueous systems at different compositions and temperatures, while the viscosity behavior, itself, was modeled by different literature models, consisting of the Grunberg-Nissan, Jouyban-Acree, McAllister, Preferential Solvation, and an Arrhenius-like viscosity model. All of the models presented satisfactory agreement, however the Preferential Solvation and the Jouyban-Acree models succeeded to achieve more reliable results as compared to the others. In addition to the mixture viscosity estimation models, the Jones-Dole viscosity model was applied to both of the aqueous systems to suggest the interactions in the mixture. By calculating and analyzing the values of the B-coefficients of this model, possibly stronger interactions among the DESs and water molecules in the mixture were suggested, as compared to the self-species interactions.

Ionic liquids are considered as new absorbents with high solubility for separation of CO2 from flue gases. In this study, the effect of an ionic liquid ([Bmim][BF4]) on the absorption of CO2 using polypropylene hollow fiber membrane contactors was studied. Aqueous solutions of ionic liquid and mixture of ionic liquid with methyldiethanolamine were applied as physical and chemical absorbents, respectively. The effects of different parameters including concentration of ionic liquid in water and aqueous solution of methyldiethanolamine as base fluids, liquid and gas flow rates, and flow direction were investigated. The results showed that a 25 wt% solution of ionic liquid can increase the absorption efficiency about 20% and 15% compared to pure water in co-current and counter-current flows, respectively. It was also observed that a mixture containing 20 wt% of ionic liquid and 10 wt% of methyldiethanolamine can improve the absorption capacity about 10% compared to a 10 wt% MDEA aqueous solution without ionic liquid.

In this study, the thermodynamic modeling of SO2 solubilities in 14 Deep Eutectic Solvents (DESs) of different nature was investigated for the first time in literature. This is a challenging mixture to model. The thermodynamic modeling approach of γ − ϕ for vapor-liquid equilibria was used. The Cubic Plus Association Equation of State (CPA EoS) was used to represent the vapor phase and the NRTL and UNIQUAC models were both investigated for the liquid phase. The DESs were considered as pseudo-components and their physical properties calculated. Both the CPA-UNIQUAC and CPA-NRTL models showed good agreement with experimental values, with total AARD% of 2.9% and 3.1%, respectively. CPA-UNIQUAC shows slightly better results, while CPA-NRTL is a simpler model. In addition to the γ − ϕ approach, the ϕ − ϕ approach was investigated for all of the systems. However, the results were not reliable, even when incorporating binary interaction parameters as adjustable parameters in the model.

Deep Eutectic Solvents (DESs), as recently introduced green solvents, are interesting for different fields and applications. Most of the known DESs have high viscosities, which change dramatically with temperature. Therefore, the viscosity of a DES is most often one of the vital physical properties which must be known accurately. Because of the strong non-ideal interactions between the constituents, as well as the dramatic changes of DES viscosity with temperature, modeling and predicting the viscosities of DESs over wide ranges of temperatures is very challenging. In this study, a viscosity approach is used and implemented into two advanced association equations of state for different families of deep eutectic solvents. The cubic plus association (CPA) and the perturbed chain-statistical associating fluid theory (PC-SAFT) equations of state (EoSs), which are two powerful models to handle associating compounds, have been coupled with the friction theory, which is itself among the successful theoretical viscosity models of literature. Twenty-seven different types of DESs, for which density and viscosity data are available in open literature, were considered. A large density databank, consisting of 590 density data over wide ranges of temperatures and pressures, together with a large viscosity databank covering 253 viscosity data over wide ranges of temperatures at atmospheric pressure were collected. The resulting friction theory models with the CPA and PC-SAFT EoSs were checked against experimental data and their deviations were found to be the same and equal to 4.4%. Such accuracy showed the promising capability of both models. By changing the hydrogen bond donor types for a fixed hydrogen bond acceptor, the accuracies of the models were also shown to be good with respect to experimental values. In addition, both models perfectly followed the trends of changing ratios of hydrogen bond donors to hydrogen bond acceptors. The viscosity-temperature trend of the different DESs was also successfully modeled.

With the aim of investigating the solutions of ethane shortage in a commercial ethylene plant, addition of propane as supplementary feedstock and increasing steam to hydrocarbon ratio were proposed as possible strategies. These strategies were proposed to compensate for the ethane shortage in the thermal cracking unit of the commercial plant. Run length, ethylene yield, and propylene yield were considered as the determining factors to appraise the strategies. The major contribution of present work would be the investigation of effect of feed shift on the run length of the steam cracker. Regarding this, five different cases were investigated in real plant condition. To include all the aspects of process, a mathematical model with reasonable assumptions was developed and then validated against the real plant data. Based on the obtained results, increasing propane concentration leads to increase in propylene yield and decrease in ethylene yield. Besides, run length of process was obtained to be longer in the cases with higher propane content in the feed stream.

The thermodynamic modeling of a new generation of solvents, deep eutectic solvents (DESs) is investigated. Because hydrogen bonding is a dominant molecular interaction, the cubic plus association (CPA) equation of state (EoS) was chosen for modeling. This is the first study to model DES density and carbon dioxide solubility using CPA. Fifteen different DESs were chosen which have density data, as well as CO2 solubility data, available in the literature over wide temperature and pressure ranges. To date, this is the most extended and global databank of DESs which has been employed in relation to a complex EoS. The density data were used to optimize the CPA parameters. The CPA EoS proved to be capable of accurately modeling pure DES densities. The validity of the optimized CPA parameters was further validated with literature density data of mixtures of DES + water, which were estimated successfully by a purely predictive procedure. To calculate CO2 solubility in DES, all the possible association schemes of ...

The use of industrial waste streams as a source of biomass is beneficial, not only to reduce environmental problems, but also to save valuable resources. Waste streams containing volatile fatty acids (VFAs) are one such example. However, separation from these streams is challenging because of the low concentrations of VFAs found in aqueous solutions. In this study, medium-chain fatty acids (MCFAs) diluted in an organic solvent are used as extractants for VFAs from dilute aqueous solutions. MFCAs have the advantage of forming double hydrogen bonds, which makes them very interesting for the recovery of VFAs. Liquid-liquid extractions (LLE) are carried out using hexanoic, octanoic or decanoic acid as the MFCA extracting agents, diluted with either hexane or toluene for economy. The various VFAs extracted consist of either acetic, propionic or butyric acid. In this manner, the effect of parameters such as the alkyl chain length of the VFAs and MCFAs and the nature of diluent have been investigated. In addition, the influence of the concentration of MCFAs in the diluent (n-hexane and toluene) on the extraction efficiency of the various VFAs has been determined. Results suggest that the decrease in extraction efficiency by diluting an MCFA with a conventional solvent is not at all a linear function of volume fraction. Therefore, a diluted MFCA has the potential to be the more economic extractant rather than a pure MCFA, as very little extraction efficiency is sacrificed over relatively large ranges of dilution.

In this study, a new simple, general, accurate and easy-to-use correlation has been developed for estimating the thermal conductivities of pure ionic liquids (ILs) over a wide range of temperatures at atmospheric pressure. In addition to the abilities mentioned, a further goal of this work was to develop a thermal conductivity correlation which does not require, as input parameters, any other physical properties, once a single thermal conductivity data point is available. This can be a valuable advantage, especially in the field of ILs for which many physical properties are unavailable. The new correlation has been proposed based on 378 thermal conductivity temperature data points from 44 different IL types. The proposed correlation, in comparison to two well-known and commonly used group contribution models and one literature correlation, shows much higher accuracy with respect to experimental values. Calculations covering all of the investigated ILs in this work resulted in AARD% values of 1.0%, for the proposed model. It is also more widely applicable, as indeed, it can estimate IL thermal conductivities with a very simple formula and without the need for other physical properties, even molecular weight and molecular structure.

Accurate knowledge of the surface tension of liquid mixtures is of considerable importance in the development of chemical processes that involve mass and heat transfer across phase interfaces. Despite the significant progress made in the development of advanced equations of state (EOS) for accurate representation of thermophysical properties, as well as sophisticated models for the thermodynamic equilibrium of highly non-ideal mixtures, they nonetheless have been to a large extent underrepresented in the prediction and correlation of the surface tension of such systems. In the current work, a modified version of the Butler equation is adopted alongside the Cubic Plus Association (CPA) EOS, with the objective of predicting and correlating the surface tension of binary liquid mixtures of associating compounds. In doing so, the experimental data of aqueous and non-aqueous mixtures of alcohols, glycols, acids, and phenol, comprised of 238 data points belonging to 18 binary mixtures are studied. It is shown that by incorporation of an association term based on the Wertheim's first-order thermodynamic perturbation theory, the CPA EOS can satisfactorily predict the values of surface tension with an AARD of only 9.78%, compared with deviations of 73.87% and 28.38% obtained for the Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) EOSs, respectively. Also, a major advantage of the proposed model is its inherent capability to simultaneously estimate the composition of the surface phase alongside the mixture surface tension. In addition, with only one adjusted binary parameter, AARDs of 5.29%, 7.09%, and 11.02% are obtained for the correlation of the experimental data using the CPA, SRK, and PR EOSs, respectively.

Deep eutectic solvents (DESs) are emerging green solvents with very unique characteristics. Their contribution to atmospheric pollution is negligible, and they can be &ldquo, designed&rdquo, for desired properties. In this study, the feasibility of applying DESs (Reline, Ethaline, or Glyceline) as absorbents in absorption refrigeration cycles was investigated. The sophisticated cubic-plus-association (CPA) equation of state, considering the strong intermolecular interactions of such complex systems, was used to estimate the thermodynamic properties. At a fixed set of base case operating conditions, the coefficients of performance were calculated to be 0.705, 0.713, and 0.716 for Reline/water, Ethaline/water, and Glyceline/water systems, respectively, while the corresponding mass flow rate ratios were 33.73, 11.53, and 16.06, respectively. Furthermore, the optimum operating conditions of each system were estimated. To verify the feasibility, results were compared to literature systems, including LiBr/water and various ionic liquid/water systems. The results indicate that DES/water working fluids have the potential to be used in such cycles. Since DESs have the characteristic to be tuned (designed) to desired properties, including their solvent power and their enthalpies of absorption, much further research needs to be done to propose new DESs with higher energy efficiencies.

Nowadays, Deep Eutectic Solvents (DESs) are considered as green solvents in many research fields. Knowledge of the physical properties of DESs can pave the way to their useful utilization. One of the important properties of a DES is its heat capacity. Besides experimental measurements, which are expensive and time consuming, it is vital to have models for the estimation of heat capacities. A generalized model is presented to estimate the heat capacities of DESs. In this regards, 505 isobaric heat capacity data points, over the wide temperature range of 278.15 to 363.15 K, from 28 DESs of different natures were used to develop the model. Up to date, this is the largest data bank investigated for isobaric heat capacities of DESs in the open literature. Based on this database, a simple, straightforward, yet precise correlation was developed to estimate the heat capacities of DESs as a function of temperature, molecular weight, critical pressure, and acentric factor. The absolute average relative deviation (AARD%) of the proposed correlation for all of the investigated data points is 4.7%, which shows that the calculated results are quite promising for such complicated systems. To the best of our knowledge, up to now, there are no generalized models for estimating the heat capacities of deep eutectic solvents, and this is the first model in the literature, therefore, it can be of great value to researchers in the field. The model has even further significance when considering that it is actually needless of any experimental data as input. This is because the physical properties used in the correlation to identify the substance are themselves obtained by group contribution methods. In practice, the only required information to use this simple and predictive model is the chemical structure.

Styrene is one of the most important monomers utilized in the synthesis of various polymers. Nevertheless, during distillation, storage, and transportation of ST, undesired polymer (i.e., UP) formation can take place. Thus, the control of undesired polymerization of styrene is a challenging issue facing industry. To tackle the mentioned issue, the antipolymer and antioxidant activity of stable nitroxide radicals (i.e., SNRs) and phenolics in styrene polymerization were studied by density functional theory (DFT) calculation and experimental approach. The electrophilicity index and growth percentage have been determined by DFT calculation and experimental approach, respectively. It is depicted that 2,6-di-tert-butyl-4-methoxyphenol (DTBMP) and 2,6-di-tert-butyl-4-methylphenol (BHT) from phenolics, and 4-hydroxy-2,2,6,6-tetramethyl piperidine 1-Oxyl (4-hydroxy-TEMPO) and 4-oxo-2,2,6,6-tetramethylpiperidine 1-Oxyl (4-oxo-TEMPO) from stable nitroxide radicals were the most effective inhibitors. Also, the growth percentage of DTMBP, BHT, 4-hydroxy-TEMPO, and 4-oxo-TEMPO after 4 h were 16.40, 42.50, 24.85, and 46.8, respectively. In addition, the conversion percentage of DTMBP, BHT, 4-hydroxy-TEMPO, and 4-oxo-TEMPO after 4 h were obtained to be 0.048, 0.111, 0.065, and 0.134, respectively. Furthermore, the synergistic effect of these inhibitors was investigated experimentally, indicating that DTMBP/4-hydroxy-TEMPO exerted the best synergistic effects on the inhibition of polymerization. The optimum inhibition effect was observed at the blend of 4-hydroxy-TEMPO (25 wt.%) and DTMBP (75 wt.%,) corresponding to 6.8% polymer growth after 4 h.

In this study, the densities of the pseudo-binary systems of water and the deep eutectic solvent, 1 choline chloride + 4 phenol were measured and reported for the first time in literature, and a comprehensive investigation on the various volumetric properties was carried out. Nine mixtures, with different compositions of water, were prepared. The densities of the prepared mixtures, as well as pure water and pure deep eutectic solvent (DES) were measured within a temperature range of 293.15–333.15 K at atmospheric pressure. Various volumetric properties, such as excess molar volumes and isobaric volume expansions, partial molar volumes and excess partial molar volumes were calculated for the investigated compositions. Furthermore, partial molar volumes and excess partial molar volumes at infinite dilution were estimated for water and the DES. By analysing the calculated properties, the interstitial accommodation effect was suggested for the investigated mixtures. The stronger tendency of water to be solvated in the mixture, as compared to the DES, was observed for all investigated temperatures. This suggests that, most probably, hydrogen bonds in the investigated mixtures are established in a manner in which water molecules are located at central positions, surrounded by the DES pseudo-molecules.

A group contribution procedure, on the basis of SAFT-γ equation, is extended to cover new families of imidazolium-based ionic liquids (ILs), with either the [MeSO3], [MeSO4], [EtSO4] or [CF3SO3] anions. The IL groups of the SAFT-γ equation were fit to IL density data at temperatures from 293.15 to 393.15 K. Pressures varied up to 60 MPa. The groups corresponding to the CO2+IL systems were optimized by the solubility data of CO2 in the ILs. The binary system data covered temperatures from 273.15 to 413.15 K, with pressures going up 27 MPa. In addition to the accuracy of estimations, the strength of SAFT-γ in predictions was investigated by estimating both the density of ILs, and the bubble-point pressures for some mixtures of CO2+ILs which were not considered in the fitting process. The average absolute relative deviations in density and bubble pressure predictions did not exceed 2.78% and 4.97%, respectively.

In this study, focused radio wave (RW) assisted leaching was investigated for the first time to considerably enhance the efficiency of copper leaching from its low-grade ores. For this purpose, the effect of exposure to radio wave electromagnetic irradiation was experimentally investigated. Two series of leaching tests were conducted, in the form of agitated slurry and fixed-bed column modes. The experimental results indicated a significant improvement of recovery in both modes. The most probable mechanisms for enhanced recoveries could be the dielectric heating through concentrated irradiation. For less than 24 h of leaching in the fixed-bed column under irradiation, the recovery improved by about 40% (~60% for leaching vs. ~100% for RF leaching), as compared to the same tests with no irradiation, while the agitated leaching tests showed an increase of up to 10% under irradiation. It is concluded that electromagnetic technology, even in the range of radiofrequency (

CO2 solubilities in the deep eutectic solvent (1 choline chloride +3 triethylene glycol) were measured at the four temperatures of 303.15, 313.15, 323.15 and 333.15 K and pressures up to 30 bars. Measurements were carried out in a newly designed, built and validated high pressure solubility apparatus. The measured data were modeled by the cubic plus association (CPA) and the Soave-Redlich-Kwong (SRK) equations of state, with AARD% values of 5.52% and 7.30% for the CPA and SRK EoSs, respectively, showing the good correlative ability of both models. Furthermore, by calculating the standard Gibbs free energies of dissolution, standard enthalpies of dissolution and standard entropies of dissolution at infinite dilution, we found that the dissolution process is nonspontaneous and exothermic, with the CO2 - DES interactions being the stronger interactions. The solution becomes less chaotic and reaches a higher degree of order in the liquid phase after dissolution of CO2.

In this work, a three layer feed-forward artificial neural network, with 24 neurons, was constructed to estimate the viscosities of a wide range of ionic liquid families, including those based on the imidazolium, ammonium, pyridinium, pyrrolidinium, phosphonium, and isoquinolinium cations, together with various anions, as well as varying lengths of alkyl side-chain lengths. The model is a function of the molecular weight and structure of the ionic liquid, and the system conditions of temperature and pressure. It covers a temperature range of (273.15 to 393.15) K and a pressure range of (0.1 to 150) MPa. Results indicated the estimated values of viscosities of pure ionic liquids to be in good agreement with the experimental data. The training (correlating) and validation coefficients (R) were 1.00000 and 0.99955, respectively, while the training and validation performances (MSE) on the training and validation datasets were 4.36 × 10 − 8 , and 1.63 × 10 − 6 , respectively. The average absolute error value on the test dataset was 1.310%.

In recent years, absorption of carbon dioxide using nanofluids has increasingly gained attentions due to its unique advantages. In this study, the absorption of carbon dioxide using Sulfinol-M based nanofluids were investigated. Functionalized MWCNTs and Fe3O4 nanoparticles were dispersed in the absorbent in order to study their effects on absorption rate and equilibrium amount of absorption using a high pressure vessel equipped with a magnetic stirrer. The effects of different parameters including nanoparticle type, nanoparticle concentration in Sulfinol-M and initial pressure of CO2 in gas phase were investigated. The obtained results revealed that the presence of both nanoparticles in the based solvent can enhance the rate of absorption and also the equilibrium solubility to a maximum amount of 46.7% and 23.2%, respectively. MWCNT shows better effects and it increases the solubility up to 7.3% more than Fe3O4 nanoparticle under the same condition. In addition, the possible mechanisms regarding mass transfer augmentation and equilibrium solubility enhancement are discussed.

A simple and general atomic group contribution method is developed for the prediction of liquid densities of ionic liquids as a function of temperature and pressure. Available literature data are used as a comprehensive database, consisting of 25 850 data points for a vast variety of ionic liquid families, and within wide ranges of pressures (0.10–300 MPa) and temperatures (217.58–473.15 K). In developing the group contribution model, the idea was to propose a simple equational form, with straightforward groups which will be easy to use, yet be general and predictive for a vast range of ionic liquids at the same time. To do this, as functional groups, we have chosen atoms and a few small and simple groups. This feature makes the model rather capable and global for a wide range of ionic liquids. Despite the generality and simplicity of the model, and by considering that the only necessary information required to use this method is the chemical structure of the ionic liquid, a good accuracy (AARD% of 0.95%)...

Due to importance of acetylene removal from ethylene rich stream in polymerization units in order to prevent formation of highly explosive compounds, presenting any strategies improving the process efficiency has attracted researchers and industries interests. Proposing novel configurations in the reaction-regeneration cycles with lower energy consumption and enhanced catalyst lifetime leading to profits for the polymerization units is of a great interest. In this regard, a new configuration for the tail-end acetylene hydrogenation reactor of a commercial olefin plant was proposed in the present study. Based on the proposed configuration, a new protocol is applied to the process for utilizing total capacity of active catalysts in each fixed bed. A mathematical model based on component and energy balance was developed and validated to evaluate the operability of the proposed configuration. Operation of different runs in the new protocol was compared with the conventional configuration. The obtained results revealed that the new configuration is managed to decrease the volume of the regenerated catalyst in a 4-year period of operation. A 33.3% decrease in the volume of the regenerated catalyst was observed. Such an achievement was obtained without reducing acetylene conversion and ethylene yield.

In continuation of our earlier publication on the phase behavior of binary and ternary mixtures involving acetaldehyde, Versatic 10, and Veova 10, in this work we present bubble-point pressures of the binary and ternary systems of acetaldehyde, Versatic 9, and Veova 9. The measurements were carried out in the Cailletet equipment, which operates according to the synthetic method. The solubility data are presented within a temperature range of 298-353 K for the two binaries of acetaldehyde + Versatic 9 and acetaldehyde + Veova 9. The pressures required for complete solubility into one homogeneous phase ranged from 0.083 to 0.414 MPa in the temperature and concentration range considered. While both Versatic and Veova contain a C=O group, Versatic also contains an alcoholic OH, which makes its solubility in acetaldehyde more difficult. The solubility curve of Versatic 9 not only shifts to higher pressures compared to that of Veova 9, but also has an increased curvature, indicating its greater deviations from ideality. As the alkyl chain is increased by one carbon number to Veova 10 and Versatic 10, the absence and presence of the OH group in Veova and Versatic also result in greater and smaller curvatures of the solubility curves, respectively. The Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) equations of state were used to model phase equilibria of the binary systems of acetaldehyde + Versatic 9 and acetaldehyde + Veova 9. Results showed that both models have good agreement with the experimental values in this study. Two ternary mixtures of acetaldehyde + Versatic 9 + Veova 9 were also investigated experimentally for their bubble point pressures. While both components have one C=O group, Versatic 9 also contains an alcoholic OH, which Veova 9 lacks. Therefore, nonideal interactions are increased between the molecules of acetaldehyde and Versatic 9 due to the presence of this hydrogen-bonding group, as compared to the system of acetaldehyde + Veova 9.