Search

The experimental liquid – liquid equilibrium (LLE) data for three ternary mixtures containing an ionic liquid (IL) (1-butyl-3-methyl imidazolium thiocyanate [Bmim][SCN]), alkanes ( n -hexane, n -octane and n -decane) and sulfur compound (thiophene) have been measured experimentally. Distribution and selectivity coefficients have been calculated using experimental data. The LLE data have been obtained at 25 °C and ambient pressure. The experimental LLE data of ternary mixtures have been compared with our previous works. It has been shown that the IL with higher molecular weight of cation has higher solute distribution and lower selectivity coefficients. It has been found that the solubility decreases as the cation length decreases, meanwhile ILs cation chain length has a remarkable effect on solubility of alkanes. Moreover, the experimental data have been demonstrated that the selectivity decreases as alkane chain length of alkane decreases while the solubility of alkanes in the ILs increases, hence the removal costs of aromatic sulfur components will be increased. The results show that [Bmim][SCN] has the lowest alkane solubility and highest selectivity coefficient, in the system containing n -decane and thiophene. A comparative study reveals that compared to other ILs, [Bmim][SCN] is a more suitable solvent. Finally, the experimental data have been correlated utilizing non-randomness two liquid (NRTL) model. The binary energy parameters were obtained, it can be seen that the model can correlate the experimental data efficiently. [ABSTRACT FROM AUTHOR]

In this work liquid–liquid equilibrium (LLE) data for aqueous two–phase system (ATPS) containing polyethylene glycol 6000 (PEG–6000) and Na 2 CO 3 were measured at T = (293.15, 303.15 and 313.15) K. Our results showed that increasing temperature expands the two–phase region; meanwhile large two–phase region was seen in this system which makes it applicable for industrial purposes. Experimental data were modeled using UNIQUAC, Extended UNIQUAC (E–UNIQUAC) and e–NRTL models to obtain binary interaction parameters. The model parameters were obtained using Shuffled Complex Evolution (SCE) optimization algorithm. The results showed that all studied models were in good agreement with the experimental data. Average deviation (%Δ w ) of e–NRTL, E–UNIQUAC and UNIQUAC models were 1.26, 1.37 and 3.46%, respectively. Finally in order to check the predictability of the E–UNIQUAC model, liquid–liquid equilibrium in systems containing PEG with different molecular mass (1000, 3350, 4000 and 8000) and Na 2 CO 3 were studied; It was found that liquid–liquid equilibrium data can be predicted satisfactorily using adjusted parameters in this work. [ABSTRACT FROM AUTHOR]

In this study, liquid–liquid equilibrium measurements were performed for the ternary (water/non-ionic surfactant/decane) systems at T = 298.15 K and atmospheric pressure. Propylene glycol mono propyl ether and ethylene glycol monobutyl ether were selected as surfactant; the first one is propylene glycol ether, while the second one is ethylene glycol ether. New experimental liquid–liquid equilibrium data were presented for the corresponding systems. Effect of salinity and surfactant structure (EO or PO functional group) on the phase behavior of such systems has been studied by both experimental measurements and thermodynamic modeling. The experimental phase behavior data were predicted by the perturbed hard sphere chain (PHSC) equation of state. In the presence of electrolyte, mean spherical approximation (MSA) term has been coupled with the PHSC EoS to account the contribution of long-range interactions. The calculated results indicate acceptable qualitative agreement of PHSC results with the experimental data. [ABSTRACT FROM AUTHOR]

Ionic Liquids (IL's) are now considered as useful alternative solvent for the desulfurization of gasoline and diesel oils by liquid–liquid extraction. In this work, 1-hexyl-3-methylimidazolium thiocyanate([Hmim][SCN]) and 1-octyl-3-methylimidazolium thiocyanate([Omim][SCN]) as ionic liquids were investigated as model solvents for removal of thiophene from some aliphatic hydrocarbons ( n -hexane, n -octane and n -decane) as fuel model. Liquid–liquid phase equilibrium data were measured for ternary systems containing one ionic liquid as solvent, thiophene as sulfur component and one aliphatic hydrocarbon as fuel model at 298.15 K under ambient pressure. It was found that the IL with lower molecular weight of cation has higher selectivity but lower solute distribution coefficients. Besides, the experimental data demonstrates that the selectivity increases as alkane chain length of fuel model increases while the solubility of ionic liquids decreases, hence the costs of desulfurization process will be decreased. Our results show that for the case of [Hmim][SCN](1) + n -decane(2) + thiophene(3) the highest selectivity and lowest alkane solubility were obtained. In other words [Hmim][SCN] is a more suitable solvent than [Omim][SCN] for desulfurization of higher alkane. Finally in order to find the model parameters, the nonrandom two liquid (NRTL) was used to correlate the experimental data. The results show the model can successfully correlate the experimental data. [ABSTRACT FROM AUTHOR]

In this study, liquid–liquid equilibriums are reported for different ternary systems of aqueous solutions with decane as oil and mono-ethylene glycol butyl ether (C 4 E 1 ) as surfactant. The appearing Winsor phases and their evolution are shown by drawing temperature versus surfactant weight fraction for a given ratio of aqueous solution to oil. The obtained diagrams have the well-known fishlike shape. Four parameters are used to discuss the influence of the additives: the perpendicular and horizontal asymptotes to the realms-of-existence of the Winsor III phase. The two horizontal asymptotes, i.e., the LCST (lower critical solution temperature) and UCST (upper critical solution temperature) show no significant changes upon adding chloride salts, except for the triethylphenylammonium cation as counter-ion. By contrast, significant changes of the values of these two parameters are found when the nature of the anion of sodium salts changes. The two perpendicular parameters γ 0 (minimum concentration of surfactant needed to form a Winsor III) and γ ˜ (minimum surfactant concentration needed to reach the Winsor IV phase from a Winsor III one) are only little affected by the nature of the additive. Two other parameters in relation with Winsor III area are also studied: δ reflects the vertical extent of the realms-of-existence of Winsor III versus temperature ( δ = UCST − LCST), while ξ = γ ˜ − γ 0 reflects its horizontal extension. The value of δ is affected by the nature of the anion of sodium salts and strongly increases in presence of Na 2 SO 4 , but also with sucrose as additive. The effect of additives has in general a more pronounced influence on the values of the LCST and UCST than on ξ . The results are discussed in terms of Hofmeister effects, of salting-in and salting-out and of the resulting depletion and adsorption on the interfacial film of the Winsor III middle microemulsion. [ABSTRACT FROM AUTHOR]

In this study, liquid–liquid equilibrium measurements were performed for different ternary, water (or brine)/decane or dodecane/mono-propylene glycol ether (C 3 P 1 ) or di-propylene glycol ether (C 3 P 2 ) systems in order to build the so-called fish phase diagrams (temperature as a function of surfactant for a given polar-apolar solvent mixture) and to compare them to the well-known water (or brine)/decane or dodecane/ethylene glycol mono-butyl ether (C 4 E 1 ) phase diagrams. The study is motivated by the lower toxicity of the C x P y compared to the corresponding C x E y . Toxicity is of particular importance for any use of such molecules in the environment. Like in the presence of C 4 E 1 , the formation of Winsor type I → III → II phase transitions with increasing temperature was observed for the C x P y systems. The LCST (Lower Critical Solution Temperature) and UCST (Upper Critical Solution Temperature) of the newly studied systems were determined. The values of the γ 0 parameter (in mole fraction), the minimum value of surfactant needed to form Winsor III, increased in comparison to the C 4 E 1 systems. The value of γ ˜ (in mole fraction), minimum value of surfactant needed to reach Winsor IV from Winsor III, was comparable using C 4 E 1 and C 3 P 1 , and lower in the presence of C 3 P 2 . The substitution of decane by dodecane led to a stronger water affinity of C 4 E 1 and C 3 P 2 as greater values of the LCST and UCST have been observed in the presence of dodecane. By contrast, a lower hydration of C 4 E 1 and C 3 P 1 was found when increasing the NaCl content in brine. It can be concluded that less toxic C 3 P 1 and C 3 P 2 can be envisaged as a substitute of the contested C 4 E 1 to formulate microemulsions and particularly Winsor III systems. [ABSTRACT FROM AUTHOR]

In this study, vapor-liquid and liquid-liquid equilibrium in mixtures containing glycol ether surfactant, non-polar and polar compounds are calculated using Perturbed Hard Sphere Chain (PHSC) equation of state (EoS). Pure liquid density and vapor pressure of surfactants are used for parameter estimation of glycol ether surfactants. The PHSC parameters are calculated for both ethylene glycol ether and propylene glycol ether surfactants. Glycol ether surfactant molecules are modeled as associating components by considering two association sites for each molecule. The results show that the PHSC model is capable of correlating thermodynamic behavior of binary (polar + surfactant) and (non-polar + surfactant) systems. Upper critical solution temperature (UCST) for hydrocarbon + surfactant and lower critical solution temperature (LCST) for water + surfactant systems are accurately calculated. The critical temperatures and the extent of immiscibility are in good agreement with the available experimental data. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the capability of the Perturbed Hard Sphere Chain (PHSC) equation of state (EOS) in liquid–liquid equilibrium calculations of salt–polyethylene glycol (PEG)–water systems is investigated. In order to present a comprehensive model, association as well as electrostatic contributions have been added to the original PHSC EOS. In this work 47 systems including PEG (with different molecular weights) and various salts have been modeled at different temperatures. Only two adjustable parameters between salt and PEG and between water and PEG have been employed. Good agreement between experimental data and calculation results is observed. Overall average deviation for all of the systems considered is 6.81%. This study shows that the PHSC EOS can be employed for correlation of phase behavior in aqueous two phase systems. [Copyright &y& Elsevier]

Abstract: In this work, the phase behavior of mixed solvent electrolyte systems containing 1-butanol+water+ammonium chloride at temperatures of 298.15, 308.15 and 318.15K and at atmospheric pressure have been studied experimentally and theoretically. For the studied systems, liquid–liquid equilibrium has been observed throughout the studied temperature range. Ammonium chloride shows a salting out effect in the two phase region, while temperature has a minor effect on the liquid–liquid equilibria in the studied temperature range. The measured experimental data have been modeled using a modified version of the extended UNIQUAC model. The model has been found to give a satisfactory description of LLE data obtained in this work, with an average absolute deviation of less than 1.5% in calculated mass fractions compared to experimental data. [Copyright &y& Elsevier]

Abstract: In this work liquid–liquid equilibria (LLE) in the system containing 1-butanol–water–sodium nitrate at temperatures of 25 and 35°C has been investigated experimentally and theoretically. The extended UNIQUAC model has previously been used for correlation of liquid–liquid equilibrium in aqueous salt systems containing alcohols. In that model the excess Gibbs energy consists of two terms, the original UNIQUAC term and Debye–Hückel term which considers the alcohol as a non-electrolyte solute. In this work, a modified extended UNIQUAC model is used by taking into account mixed solvent theories. The model consists of three terms, the original UNIQUAC term, a Pitzer–Debye–Hückel term and a Born term. The model has been found to give a satisfactory description of LLE data obtained in this work, with an average absolute deviation of less than 0.5 in calculated mass percent compared to experimental data. [ABSTRACT FROM AUTHOR]

In this work the phase equilibrium of an aqueous two phase system (ATPS) containing polypropylene glycol (PPG, molecular weight = 425 kg·mol−1) and NaClO4 was investigated at atmospheric pressure and at 288.15 and 298.15 K. Two phase regions and composition of phases were determined. Our results show that as the temperature increases, the two-phase region expands. Also, the extended UNIQUAC (E-UNIQUAC) equation was used to correlate the equilibrium data. To reduce the number of adjustable parameters, ATPSs composed of PEG and PPG were collected from the literature and simultaneously correlated using the E-UNIQUAC model. Also, the effect of temperature on the liquid–liquid equilibrium (LLE) was considered by using temperature-dependent parameters. In the modeling, two different scenarios were supposed. In the first, polymer and salt were treated as solutes (Case A), while in the second, the pseudo-solvent approach was considered (Case B). The results showed good agreement with experimental data in both cases. The average absolute deviation of the model using Case B was about 0.2% and that for Case A was about 2% in the ATPS composed of PEG. Meanwhile, the reported errors in the ATPS containing PPG for Case A and Case B were almost equal. [ABSTRACT FROM AUTHOR]

Abstract: Experimental measurements have been performed for liquid–liquid equilibria in aqueous systems containing 1-pentanol and sodium nitrate at temperatures of 298.15 and 308.15K and at atmospheric pressure. The results have been modeled using the extended UNIQUAC model and also a modified version of this model. Relevant model parameters have been adjusted using the experimental data. Both models are capable of correlating the experimental data with an average deviation of less than 0.8 weight percent, with the modified model producing slightly better results. The predictive nature of the models has also been verified. [Copyright &y& Elsevier]

[Display omitted] • Extraction of dibenzothiophene was investigated from model fuel (n-octane). • Two different Deep Eutectic Solvents were synthesized and used as extractive agents. • The structures of Deep Eutectic Solvents were confirmed by FTIR and H-NMR analyses. • Liquid-liquid equilibrium was modeled by the NRTL model. Among the most important causes of air pollution we may refer to hydrocarbon fuels with a large content of organosulfur compounds. These compounds must be removed to the level of standard concentration for which different techniques are commonly in use. Since, desulfurization of aromatic sulfur compounds, such as thiophenes, is not possible by common methods such as hydrodesulfurization, other methods should be considered. In recent years, scientists have focused on extractive desulfurization using Deep Eutectic Solvents (DES) as a new method for removing organosulfurs from hydrocarbon fuels. In this research, two new DESs are synthesized. As the model fuel, we used n-octane, and dibenzothiophene (DBT) was chosen as the organosulfur content with a 1000 ppm concentration. DESs were synthesized by mixing quaternary ammonium salts and trifluoroacetic acid in a heating method. The structures of DESs were confirmed by FTIR and H-NMR analyses. The extraction process was first carried out at temperatures ranging from 25 to 40 °C. The results showed that the best temperature was 35 °C. Then, the effect of fuel to DES mass ratio (i.e. different compositions of feed), on extraction efficiency was examined. For thermodynamic modeling of liquid–liquid equilibrium the Non Random Two Liquid (NRTL) activity coefficient model was implemented. The parameters of the NRTL model were correlated using the binary data obtained from solubility experiments. Finally, the adjusted parameters were used for predicting ternary phase equilibrium data obtained in this work. The root mean square deviation from experimental data was less than 0.11% for each solvent. [ABSTRACT FROM AUTHOR]