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The influence of different catalyst cobalt loadings on the C1-C3 hydrocarbon product yields and energy consumption in plasma-catalytic Fischer-Tropsch synthesis (FTS) was investigated from the standpoint of various reactor operating conditions: pressure (0.5 to 10 MPa), current (250 to 450 mA) and inter-electrode gap (0.5 to 2 mm). This was accomplished by introducing a mullite substrate, coated with 2 wt%-Co/5 wt%-Al2O3, 6 wt%-Co/5 wt%-Al2O3 or 0 wt%-Co/5 wt%-Al2O3 (blank catalyst), into a recently developed high pressure arc discharge reactor. The blank catalyst was ineffective in synthesizing hydrocarbons. Between the blank catalyst, 2 wt%, and the 6 wt% Co catalyst, the 6 wt% improved C1-C3 hydrocarbon production at all conditions, with higher yields and relatively lower energy consumption at (i) 10 MPa at 10 s, and 2 MPa at 60 s, for the pressure variation study, (ii) 250 mA for the current variation study, and (iii) 2 mm for the inter-electrode gap variation study. The inter-electrode gap of 2 mm, using the 6 wt% Co catalyst, led to the overall highest methane, ethane, ethylene, propane and propylene yields of 22 424, 517, 101, 79 and 19 ppm, respectively, compared to 40 ppm of methane and &lt, 1 ppm of C1-C3 hydrocarbons for the blank catalyst, while consuming 660 times less energy for the production of a mole of methane. Furthermore, the 6 wt% Co catalyst produced carbon nanotubes (CNTs), detected via transmission electron microscopy (TEM). In addition, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD) showed that the cobalt catalyst was modified by plasma treatment.

In this work, the effect of a series of zwitterionic compounds (ZIs) aqueous solutions on the thermodynamic equilibrium and kinetic conditions of carbon dioxide hydrate formation is investigated. The hydrate dissociation conditions for (CO2 + ZI + water) systems are studied at different concentrations of ZI, viz. (0.10; 0.20, 0.30) mass fraction. The experiment was performed over a temperature range of T = (272–282) K and pressures range of p = (1.27–4.31 MPa) using a high pressure equilibrium cell. In this work the following ZIs: 4-(triethylammonio)butane-1-sulfonate [N222C4S], 4-(tributylammonio)-butane-1-sulfonate [N444C4S] and 4-(tributylphosphonio) butane-1-sulfonate [P444C4S] were investigated, therefore it was possible to determine the influence of alkyl chain length and the structure of the core atom on the kinetic behaviour of carbon dioxide gas hydrate formation. The results show that the gas hydrate phase equilibrium in the presence of zwitterionic compounds is shifted to higher pressures and lower temperatures so that the ZIs act slightly as a thermodynamic inhibitor of hydrate formation.

Phase equilibrium conditions (dissociation data) for clathrate hydrates (gas hydrates) were studied for systems involving fluorinated refrigerants + water + single and mixed electrolytes (NaCl, CaCl2, MgCl2 and Na2SO4) at varying salt concentrations in the absence and presence of cyclopentane (CP). The ternary systems for (R410a or R507) + water + CP were performed in the temperature and pressures ranges of (279.8–294.4) K and (0.158–1.385) MPa, respectively. Measurements for {R410a + water + (NaCl or CaCl2) + CP} were undertaken at salt concentrations of (0.10, 0.15 and 0.20) mass fractions in the temperature and pressure ranges of (278.4–293.7) K and (0.214–1.179) MPa, respectively. The temperature and pressure conditions for the (R410a + water + Na2SO4) system were investigated at salt concentration of 0.10 mass fraction in range of (283.3–291.6) K and (0.483–1.373) MPa respectively. Measurements for {(R410a or R507) + water + mixed electrolytes NaCl, CaCl2, MgCl2} were undertaken at various salt concentrations of (0.002–0.15) mass fractions in the temperature and pressure ranges of (274.5–292.9) K and (0.149–1.119) MPa in the absence and presence of CP, for which there are no published data related to mixed salt and a promoter. The phase equilibrium measurements were performed using a non-visual isochoric equilibrium cell and the pressure-search technique. This study was focused on obtaining equilibrium data that can be utilized to design and optimize for water desalination process and the development of a Hydrate Electrolyte–Cubic Plus Association (HE–CPA) Equation of State based model. The results indicate hydrate dissociation pressure reduction/hydrate dissociation temperature increase up to ambient conditions in the presence of promoter (CP). The experimental results were then modelled. The modelling results are in good agreement with the measured hydrate dissociation data.

In this work we studied the applicability of two ionic liquids (ILs) for the separation of thiophene from octane, or hexadecane, as a model of the diesel stream. Experimental liquid-liquid phase equilibrium (LLE) data were obtained for four ternary systems {IL + thiophene + octane, or hexadecane} at T = 308.15 K and pressure p = 101 kPa. The ILs 1,3-dihydroxyimidazolium bis{(trifluoromethyl)sulfonyl}imide, [OHOHIM][NTf2] and 1-butyl-3-methylimidazolium trifluoromethanesulfonate, ([BMIM][CF3SO3]), [BMIM][OTf] were used to assess the desulfurization process. [BMIM][OTf] showed better selectivity than [OHOHIM][NTf2] in the extraction of thiophene from both, octane and hexadecane. The distribution ratio in all systems is acceptable in comparison with currently published data for different ILs. Chromatography analysis showed that the IL was not present in the octane, or hexadecane layer. This simplifies the process separating the solvent from the hydrocarbon layer. The data obtained have been correlated with the non-random two liquid (NRTL) model.

In the present study, we reported the densities and excess molar volumes for the pure organic solvent mixtures such as {toluene (x1) + acetic acid (x2)}, {cyclohexane (x1) + acetic acid (x2)}, {toluene (x1) + 1-hexanol (x2)}, {toluene (x1) + 2-octanol (x2) } and {n-heptane (x1) + 1-hexanol (x2) } at temperature range from (288.15 to 343.15) K and at a pressure of 0.1 MPa. Excess molar volumes for these binary mixtures were calculated from the experimental density data and fitted to the Redlich-Kister polynomial equation to check the accuracy of experimental data. In addition, the interactions between the unlike molecules in the mixtures were confirmed by using the experimental results. We have also study the effect of temperature on molecular interactions between the molecules in the mixtures.

Isothermal phase equilibrium data were measured for the binary systems of tetrafluoromethane with either perfluorohexane or perfluorooctane to investigate the effect of carbon chain length of the solvent with regards to the solubility of tetrafluoromethane. Both the “static-analytic” and the “static-synthetic” methods were utilized to measure the high-pressure phase equilibrium data. Isothermal measurements were performed within the temperature range of (283.15–303.15) K and at pressures up to 11 MPa. Vapour pressure data for perfluorohexane and perfluorooctane were measured within the temperature range of (283.15–323.15) K. Additionally, isothermal vapour-liquid equilibrium data were measured for the binary system of carbon dioxide + n-hexane at 313.15 K; the data were utilized to validate the experimental method. The experimental data were modeled using the Peng-Robinson equation of state with the Wong-Sandler mixing rule and Non-Random Two-Liquid excess Gibbs energy model. The model provides a satisfactory representation of the experimental data within the measured temperature range.

A new experimental setup based on the “static-synthetic” method was designed and commissioned for the measurement of solubility from vacuum to moderates pressures. The new apparatus and experimental method were extensively validated by measuring the solubility of carbon dioxide in three pure solvents, viz., n-hexane, n-methyl-2-pyrrolidone and 1-butyl-3-methylimidazolium tetrafluoroborate. New solubility data for carbon dioxide in hybrid solvents with different mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate + n-methyl-2-pyrrolidone were measured at three temperatures, viz. (298.15, 313.15 and 323.15) K. Additionally, viscosity, density and sound velocity for binary mixtures of n-methyl-2-pyrrolidone + 1-butyl-3-methylimidazolium tetrafluoroborate were measured. The experimental phase equilibrium data were modelled using the Peng-Robinson equation of state and van der Waals mixing rule. In general, the solubility of carbon dioxide in the hybrid solvent was lower than the respective pure constituents. However, the hybrid solvent exhibited a significantly lower viscosity than the pure ionic liquid.

This study explored Fischer–Tropsch synthesis (FTS) by combining a non-thermal plasma (NTP), generated by an arc discharge reactor at pressures &gt, &gt, 1 MPa, coupled with a mullite-coated 2 wt%-Co/5 wt%-Al2O3 catalyst. The FTS product yields and electrical energy consumption for the pure plasma (no catalyst) and plasma-catalytic FTS processes were compared under the scope of various reactor operating parameters, namely, pressure (0.5 to 10 MPa), current (250 to 450 mA) and inter-electrode gap (0.5 to 2 mm). The major products, obtained in low concentrations for both processes, were gaseous C1–C3 hydrocarbons, synthesised in the order: methane &gt, ethane &gt, ethylene &gt, propane. The hydrocarbon product yields were observed to increase, while the specific required energy generally decreased with increasing pressure, decreasing current and increasing inter-electrode gap. Plasma-catalysis improved the FTS performance, with the optimum conditions as: (i) 10 MPa at 10 s and 2 MPa at 60 s for the pressure variation study with the longer treatment time producing higher yields, (ii) 250 mA for the current variation study, (iii) 2 mm for the inter-electrode gap variation study. Plasma-catalysis at a gap of 2 mm yielded the highest concentrations of methane (15,202 ppm), ethane (352 ppm), ethylene (121 ppm) and propane (20 ppm), thereby indicating the inter-electrode gap as the most influential parameter.

The activity coefficients at infinite dilution, γ 13 ∞ , for 46 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, esters, aldehyde, acetonitrile, pyridine and 1-nitropropane in the ionic liquid (IL) 1-butyl-1-methylpyrrolidynium dicyanamide, [BMPYR][DCA] were determined by gas-liquid chromatography at five temperatures in range of (313.15–373.15) K at pressure, p = 101 kPa. The thermodynamic functions at infinite dilution as partial molar excess Gibbs free energy, Δ G 1 E, ∞ , enthalpy Δ H 1 E, ∞ , and entropy term T ref Δ S 1 E , ∞ and the gas-liquid partition coefficients, K L at infinite dilution were calculated from the experimental γ 13 ∞ values obtained over the temperature range. The values of selectivity and capacity for few separation problems as n-heptane/benzene, n-heptane/thiophene, n-heptane/1-heptyne, and ethylbenzene/styrene at T = 323.15 K were calculated from γ 13 ∞ and compared to literature values for [DCA]-based ionic liquids and [BMPYR]-based ILs. In comparison with the former measured [BMPYR][TCM], or [BMPYR][SCN] ILs, the [DCA]-based IL presents high selectivities for the separation of aromatic hydrocarbons from aliphatic hydrocarbons, and especially for the extraction of thiophene, or pyridine from n-heptane with slightly lower capacity than those for [BMPYR][TCM], or [BMPYR][SCN]. New data shows that [BMPYR][DCA] IL may be proposed as an alternative solvent for the separation of aliphatic from aromatic hydrocarbons.

The isothermal vapour-liquid equilibria of R-23 + 1-hexene, R-23 + 3-methylpentane, R-116 + 1-hexene and R-116 + 3-methylpentane were measured at temperatures of between (293.1 and 313.3) K with a static-analytic apparatus. Vapour-liquid-liquid equilibria was exhibited by the R-116 + 1-hexene system. The equilibrium data was modelled with the PR EOS, modified with the MC alpha function, and the WS mixing rule with either the NRTL or the UNIQUAC activity coefficient model. Both the temperature dependent and the temperature independent forms of the models were regressed to the experimental data. The method of Ungerer et al. was used to extrapolate the subcritical co-existence data to the mixture critical loci, while the method of Heidemann and Khalil was used to estimate the critical locus curves for the systems. Each of the four systems were also categorised according to the classification system of van Konynenburg and Scott.

The isothermal vapour-liquid and vapour-liquid-liquid equilibria of five binary refrigerant + n-alkane systems at near ambient temperatures were measured using a static-analytic apparatus and a static-synthetic apparatus. The phase equilibrium data for the systems of trifluoromethane (R-23) + n-nonane and hexafluoroethane (R-116) + n-decane were measured using the static-analytic apparatus, whereas bubble point data were measured with the static-synthetic apparatus for the systems of R-23 + n-decane, R-23 + n-undecane and R-116 + n-nonane. The temperatures that were investigated for these systems ranged between (272.9 and 323.1) K. The experimental phase equilibrium data were modelled with the PR EOS and the MC alpha function. The WS mixing rule, incorporating either the NRTL or the UNIQUAC activity coefficient model, was used to apply the model to the mixture data. The temperature independent forms of the thermodynamic model were found to provide a more accurate representation of the experimental data than the temperature dependent forms. A single mixture critical point was determined using the indirect extended scaling laws of Ungerer et al. (2005). The calculation procedure of Heidemann and Khalil (1980) was used to estimate segments of the critical locus curves for the binary systems for which data were measured close to the critical locus curve. The van Konynenburg and Scott classification for each system was defined, based upon the characteristics of the critical locus curves within the temperature ranges that were studied.

A computational tool integrated into a commercial simulation software (CHEMCAD) is developed for the analysis and synthesis of crystallization processes. The tool utilizes the comprehensive thermodynamic models and the rigorous computational algorithms available. The crystallization calculations are formulated as multicomponent multiphase equilibrium phase calculations and support the analysis of various modes of crystallization, such as cooling, evaporative, and the use of mass separating agents such as antisolvents and cosolvents. The tool is demonstrated with applications related to the crystallization of API’s and LCD crystals.

In this communication, the effects of initial temperature and pressure, aqueous TBAB (tetra- n -butylammonium bromide) solution concentration, and sodium dodecyl benzene sulfonate (SDS) concentration on the kinetic behaviour of semi-clathrate hydrates of Ar + aqueous TBAB solutions were investigated. Kinetic experiments were performed in a high pressure equilibrium cell with an inner volume of approximately 40 cm 3 at initial temperatures of (281, 285 and 287.5) K and initial pressures of (6.1, 8.1 and 10.1) MPa. The results indicate that induction time decreases significantly with an increase in the initial pressure. However, the kinetic constant, and consumption of Ar during the semi-clathrate hydrate formation, increases. The same trends were detected with a decrease in the initial temperature, at a constant pressure. In addition, with an increase in the TBAB concentration, from 0.1 to 0.3 mass fraction TBAB, the rate of semi-clathrate hydrate nucleation and consumption of Ar, increases during the hydrate formation, while the induction time decreases, significantly. The results therefore show a positive kinetic effect of TBAB on Ar hydrates which indicates that TBAB is a reliable promoter to increase the rate of argon hydrate formation. The results for the addition of SDS (at concentrations of 100, 200 ppm) at initial temperatures of 285 K and initial pressures of (6.1 and 8.1) MPa indicate that SDS increases the induction time of the semi-clathrate hydrate formation for the system of Ar + 0.1 mass fraction TBAB + 0.9 mass fraction water, but there is no systematic trend between induction times and the SDS concentrations for this system.

Experimental data on dissociation conditions of carbon dioxide clathrate hydrate in the presence of KBr, CaBr2, MgCl2, HCOONa, and HCOOK aqueous solutions, as well as methane clathrate hydrate in the presence of HCOONa and HCOOK aqueous solutions have been measured and are reported in this study. Measurements were conducted in the temperature and pressure ranges of (266.9–285.8) K and (1.47–9.68) MPa, respectively, using an isochoric pressure-search method. Results reveal that at varying concentrations, the aqueous salt solutions have a satisfactory inhibition effects on both carbon dioxide and methane hydrate formation, causing a shift in the P-T (pressure–temperature) equilibrium cruves to higher pressures and lower temperatures. A thermodynamic model based on the solid solution theory of van der Waals and Platteeuw (vdW-P) was used for estimation of hydrate dissociation conditions in the presence of the salt aqueous solutions. The gas phase was modeled using the Valderrama modification of the Patel-Teja equation of state (VPT EoS). The UNIQUAC approach, along with the Debeye-Huckel method, was applied to calculate the activity coefficient of water in the presence of salt. The UNIQUAC interaction parameters between water and anions and cations were optimized using the measured hydrate dissociation data. The model results provide a reasonable agreement with the experimental data, with an average absolute deviation (ARD%) below 0.3%.

A new equilibrium cell featuring a floating piston with an internal variable volume and phase sampling mechanism was designed and commissioned for the measurement of phase equilibrium data. The experimental technique can be extended to the static-combined method. The apparatus was tested by measuring vapor-liquid equilibrium data for the binary system of carbon dioxide + n-hexane at 313.15 K. New experimental vapor-liquid equilibrium data were also measured for the binary systems of carbon dioxide + 1,1,2,2 tetrafluoroethyl 2,2,3,3 tetrafluoropropyl ether at four temperatures, viz. (303.15, 313.15, 323.15 and 333.15) K and modeled using the Peng-Robinson Equation of State. Data close to the mixture critical points were modeled using a scaling law. The average expanded uncertainty for T, P, x1 and y1 for all systems in this work were 0.08 K, 0.002 MPa, 0.004 and 0.0007, respectively.

An apparatus based on the “static-analytic” method was designed and commissioned. The apparatus was tested by measuring vapour-liquid equilibrium data for the binary system of carbon dioxide + chlorodifluoromethane at 273.15 K. There is excellent agreement between the experimental data and previous measurements reported in the literature. New experimental vapour-liquid equilibrium data were also measured for the binary systems of ethylene + chlorodifluoromethane at five temperatures, viz. (273.15, 293.15, 313.15, 333.15, and 353.15) K. At the same temperatures (excluding 273.15 K) the critical points of the binary mixtures were also experimentally determined. The experimental data for this binary system were accurately correlated using the Peng–Robinson Equation of State utilizing the Wong–Sandler mixing rule coupled with the Non-Random Two-Liquid (NRTL) activity coefficient model.

In this work, densities (ρ), ultrasonic sound velocities (u) and viscosities (η) for binary mixture of tri(butyl)methylphosphonium methyl sulfate ([P4441][CH3SO4]) with N-methyl-2-pyrrolidone (NMP) were measured over the entire composition range at temperatures ranging from 293.15 to 323.15 K in steps of 5 K under atmospheric pressure. The derived properties such as excess molar volumes (VE), deviation in isentropic compressibilities (Δκs) and deviation in viscosities (Δη) are obtained from ρ, u and η data, respectively. The derived properties were correlated accurately with the Redlich-Kister type equation. The VE, Δκs and Δη values for the aforesaid systems are negative over the entire composition range under the present experimental conditions. The molecular interactions and structural effects were examined on the basis of measured and derived properties. The obtained results are useful for describing the intermolecular interactions, developing structure-property correlation and molecular modeling that exist between [P4441][CH3SO4] with NMP mixture.

Solubility measurements were performed for the systems (11β)-11,17,21-trihydroxypregna-1,4-diene-3,20-dione (prednisolone) and (11β)-11,17,21-trihydroxypregn-4-ene-3,20-dione (hydrocortisone) in 10 solvents at atmospheric pressure within the temperature range, T = (293.2 to 328.2) K by employing combined digital thermal analysis and thermal gravimetric analysis (DTA/TGA) to determine liquid phase compositions at saturation. The maximum solubility for prednisolone and hydrocortisone was in N , N dimethylformamide at 328.2 K with x 1 = 0.0141 and x 1 = 0.0142 respectively. The lowest solubility was found to be prednisolone and hydrocortisone in water at 293.2 K with x 1 = 0.0000105 and x 1 = 0.0000115 respectively. The composition data was modelled using the Tsuboka-Katayma modified Wilson and NRTL activity coefficient models. There is satisfactory agreement between the experimental results and the models chosen. Furthermore, melting points and enthalpies of fusion of prednisolone and hydrocortisone were determined by combined DTA/TGA. The enthalpy of fusion and melting point of prednisolone and hydrocortisone was found to be 36,145 J·mol − 1 and 514.5 K and 33,900 J·mol − 1 and 486.1 K respectively.

Densities and sound velocities of three binary systems containing glycerol + (water, methanol, or ethanol) have been measured over the entire composition range at temperatures ranging from (283.15 to 313.15) K in 10 K intervals, at atmospheric pressure. A vibrating u-tube densimeter and sound velocity analyzer (Anton Paar DSA 5000M) was used for the measurements. Thermodynamic properties were derived from the measured data, viz. excess molar volume, isentropic compressibility, and deviation in isentropic compressibility. The property data were correlated with the Redlich-Kister polynomial. In all cases, the excess molar volumes and deviation in isentropic compressibility are negative over the entire composition range for all binary mixtures studied and become increasingly negative with an increase in the temperature. These properties provide important information about different interactions that take place between like-like, like-unlike and unlike-unlike molecules in the mixtures.

In this work, the systematic study of the physicochemical and excess properties of binary mixtures of carboxylic-based ionic liquids with water is presented. The ILs studied, 1-ethyl-1-methylpyrrolidinium acetate, [EMPYR][AcO], 1-ethyl-1-methylpyrrolidinium glycolate, [EMPYR][Gly] and 1-ethyl-1-methylmorpholinium glycolate, [EMMOR][Gly] were synthesized in our laboratory, and their structures confirmed by NMR technique. In addition, basic thermophysical characterization of pure ILs was determined using the DSC technique. The density, ρ and dynamic viscosity, η were measured over the entire composition range as a function of temperature from (298.15 to 348.15) K at 101.3 kPa. From the experimental results, excess molar volumes, V E and dynamic viscosity deviations, Δ η were calculated and described using the Redlich-Kister equation. The influence of the IL structure on the transport and thermodynamic properties is discussed.

In this perspective, the main intention is to reveal the possible intra and inter molecular interactions between ternary ionic liquid systems. The excess molar volume ( V 123 E ), isentropic compressibility (ks) and deviation in isentropic compressibility ( Δ k s 123 ) were determined for two ternary liquid mixtures of {[C2mim][EtSO4] (x1) + acetic or propionic acid (x2) + acetonitrile (x3)} at different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15) K and at p = 1 × 105 Pa with the aid of the experimental density (ρ) and speed of sound (u) measurements. The calculated ternary excess volume and deviation in isentropic compressibility results were correlated by using the Cibulka equation with the aid of Redlich–Kister parameters obtained from literature corresponding binary systems. Furthermore, the measured thermodynamic properties are discussed in terms of molecular interactions between component molecules in liquid mixtures.

Solubility measurements at equilibrium were performed for the systems (3β,25 R )-spirost-5-en-3-ol (diosgenin) and (16α,17β)-estra-1,3,5(10)-triene-3,16,17-triol (estriol) in at least 12 solvents at atmospheric pressure within the temperature range T = (293.2–328.2 K) using combined digital thermal analysis and thermal gravimetric analysis (DTA/TGA) to determine compositions at saturation. The results were modelled with the NRTL and Tsuboka-Katayma modified Wilson activity coefficient models. The models employed provided a satisfactory correlation of the experimental data. Furthermore melting points and enthalpies of melting of diosgenin and estriol were determined by combined DTA/TGA.

Fil: Gonzalez Prieto, Mariana. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Bahia Blanca. Planta Piloto de Ingenieria Quimica. Universidad Nacional del Sur. Planta Piloto de Ingenieria Quimica; Argentina

Isothermal vapour-liquid equilibrium (VLE) data were measured for 2-propanone + 2-butanol at (333.15 and 353.15) K and 2-propanone + propanoic acid at (333.15, 353.15, and 373.15) K. For the sub-atmospheric pressure measurements, a dynamic recirculating VLE glass still operated isothermally was used, whilst a novel recirculating stainless steel of similar architecture, capable of operating at pressures up to 750 kPa was used for measurements above atmospheric pressures. The experimental VLE data for the 2-propanone + 2-butanol system at (333.15 and 353.15) K were correlated to the Wilson and NRTL models using the gamma-phi approach with the Hayden and O'Connell correlation employed for calculating the second virial coefficients. For the 2-propanone + propanoic acid system, the considerably more complex iterative procedure of Prausnitz et al. [J.M. Prausnitz, T.F. Anderson, E.A. Grens, C.A. Eckert, R. Hsieh, J.P. O'Connell, Computer Calculations for Multicomponent Vapour-Liquid and Liquid-Liquid Equilibrium, Prentice- Hall, New Jersey, 1980] was utilized to account for acid dimerization in the vapour phase. In the computational procedure for finding liquid phase activity coefficients, true species vapour phase mole fractions (ηi) are solved for, with the equilibrium association constant, Ki emerging from the computations. The thermodynamic consistency of the data was verified through the point and direct test methods of Van Ness.

Experimental vapour-liquid equilibrium data are reported for the binary systems of ethylene + perfluoro-n-heptane and ethylene + perfluoro-n-nonane. Isothermal measurements were performed within the temperature range of (293–354) K, and at pressures up to 9 MPa, using an apparatus based on the “static-analytic” method. The experimental data were correlated using the Peng–Robinson equation of state utilizing either the van der Waals mixing rule or the Wong–Sandler mixing rule coupled with the Non-Random Two-Liquid (NRTL) activity coefficient model. Both model combinations provided adequate representation of the experimental data, with the model involving the Wong-Sandler mixing rule providing a slightly better fit.

2-Phenylethanol (PEA) is an important alcohol involved in aroma and flavour of food, soft drinks, candy, ice cream, pudding, chewing gum and cookies. This study investigates the ability of three tetracyanoborate-based ionic liquids (ILs) for the extraction of PEA from aqueous phases. In this regard, experimental measurements of liquid-liquid equilibria (LLE) in the binary systems {IL (1) + PEA or water (2)} and ternary systems of {IL (1) + PEA (2) + water (3)} at temperature T = 308.15 K and ambient pressure were undertaken. The ILs investigated were 1-hexyl-3-methylimidazolium tetracyanoborate [HMIM][TCB], 1-decyl-3-methylimidazolium tetracyanoborate [DMIM][TCB], and 1-butyl-1-methylpyrrolidinium tetracyanoborate [BMPYR][TCB]. The suitability of the ILs for use as entrainers for the extraction of PEA from water has been evaluated in terms of the selectivity and solute distribution ratio. An immiscibility gap was observed in the binary systems of (IL + water). All ILs showed complete miscibility with PEA in the liquid phase at a temperature T = 308.15 K. The average selectivity of the extraction of PEA from water increases in the following order: [HMIM][TCB] ( S av = 408) S av = 509) S av = 577). The solute distribution ratio increases in the following order: [HMIM][TCB] ( β av = 178) β av = 198) β av = 241). The best IL with the highest selectivity and acceptable distribution ratio is [DMIM][TCB]. The LLE data for the systems were correlated with the NRTL model. The model satisfactorily describes the solubility of the ternary systems with an average root mean square deviation of σ x = 0.005.

Cellulose has been identified as the most abundant renewable material but however utilization of cellulose is still limited, it does not dissolve in most convectional solvents. This study focusses on cellulose dissolution using ionic liquids (ILs) namely: 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]), 1-allyl-3-methylimidazolium chloride ([AMIM][Cl]) and 1-butyl-3-methylpyridinium chloride ([BMPy][Cl]) with N,N-dimethylformamide (DMF) co-solvent. The solubility of the cellulose was tested in pure ILs as well as in solution of ILs/DMF. Results showed that solubility of the cellulose in ILs greatly enhanced in the presence of DMF. The complete dissolution of cellulose in both the systems such as pure ILs and ILs/DMF was also evident by density (ρ), sound velocity (u) and refractive index (nD) measurements. Furthermore, COSMO-RS analysis was also performed in order to achieve a better understanding of the molecular interactions between the ILs and the co-solvent. In addition to the above theoretical chemistry tools, natural bond orbital (NBO), Fragment molecular orbital (FMO) and chemical reactivity analyses for cellulose molecule was investigated. Theoretical data obtained proved that cellulose molecule is more reactive than glucose. In addition, this study also deals with the regeneration of the cellulose from dissolved solution using deionized water. The regenerated cellulose was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. It was observed that the cellulose regenerated cellulose from both solvent systems hold excellent mechanical properties.

Ten derivatives of (2Z,4E)-3-hydroxy-1-(2-hydroxyphenyl)-5-phenylpenta-2,4-dien-1-one were investigated for their antioxidant properties and corrosion inhibition potential. The compounds were screened for their antioxidant activity using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging assay and the ferric reducing antioxidant power (FRAP) assay. The methoxylated analogues generally showed better antioxidant activity than the fluorinated analogues. The compounds were screened for drug-likeness properties using in silico techniques. They were found to obey the Lipinski rule of five, which indicated promising absorption or permeability properties through biological membranes. The flexible-ligand docking studies were performed using Auto Dock 4.2 with protein tyrosinase (PDB code: 3NM8 ). Furthermore, the methoxy derivatives exhibited relatively high binding energies, indicating the possibility of greater interactions with proteins. The compounds were also tested for possible anticorrosion properties using the potentiodynamic polarization and electrochemical impedance spectroscopy techniques. All the compounds showed appreciable corrosion inhibition efficiency for mild steel in 1 M HCl. These compounds are mixed-type inhibitors. The adsorption of the compounds on a mild steel surface obeyed the Temkin adsorption isotherm and the derived adsorption thermodynamic parameters indicate a spontaneous and chemical adsorption process.

Isothermal vapour-liquid equilibrium (VLE) values for two binary systems; trifluoromethane and n-heptane at temperatures between T = (272.9 and 313.2) K, and hexafluoroethane and n-heptane at temperatures between T = (293.0 and 313.2) K were measured with a static-analytic apparatus. Bubble pressures at temperatures between T = (293.0 and 313.2) K, at several compositions, were also measured with a variable-volume static-synthetic apparatus. Vapour-liquid-liquid equilibrium (VLLE) was found to occur for certain isotherms for both of the systems. The PR EOS, with the Mathias-Copeman (MC) alpha function, combined with either the classical mixing rule or the Wong-Sandler (WS) mixing rule was used to correlate the experimental results. Either the NRTL or the UNIQUAC activity coefficient model was used within the WS mixing rule. The indirect extended scaling laws of Ungerer et al. were used to extrapolate critical loci from the experimental coexistence data, and the calculation procedure of Heidemann and Khalil was employed to calculate the mixture critical locus curves at temperatures close to the refrigerant critical temperatures. At lower temperatures on the mixture critical curve, gas-liquid critical points occurred, whereas, at higher temperatures, the critical points occurred along a liquid-liquid locus curve. The two systems were categorised according to the van Konynenburg and Scott classification.

The gas-phase reaction of hexafluoropropene and molecular oxygen was investigated in a tubular flow reactor at 450 kPa and within a temperature range of 463–493 K using HFP/O2 mixtures containing 20–67% HFP on a molar basis. Capillary and packed column chromatography served as the main analytical technique. The reaction yielded HFPO, COF2, CF3COF, C2F4 and c-C3F6 as gas-phase products. High molecular weight oligomers were also formed. The oligomers were found to have a polyoxadifluoromethylene structure according to elemental and 19F NMR analysis. At 493 K HFP is proposed to undergo oxygen-mediated decomposition to difluorocarbene radicals, yielding greater quantities of difluorocarbene recombination products. Kinetic parameters for a revised model of the oxidation process were identified through least squares analysis of the experimental data.

In this study the cloud point pressure for the solubility of copolymers of vinyl acetate and dibutyl maleate in supercritical carbon dioxide were measured and modeled. The copolymers investigated have different molecular weights, with varying structures. The cloud point pressure data were modeled using the Perturbed Chain Polar Statistical Associating Fluid Theory (PCP-SAFT) equation of state (EoS) that was developed for the prediction of the phase behavior of polar polymers which are soluble in supercritical carbon dioxide (J. of Supercritical Fluids 97 (2015) 45–50). Using this model, the cloud point pressure of the polymer-supercritical CO 2 systems were correlated by taking into account quadrupole-quadrupole interactions between carbon dioxide and the polymer segments through the PCP-SAFT EoS. Thus, the new parameters were determined for the copolymers studied in this work. Moreover, we applied PC-SAFT EoS for the same systems. It is shown that the results are obtained using the PCP-SAFT EoS is superior respect to PC-SAFT so that the present EoS can be applied to calculate the cloud point pressure of the copolymer-CO 2 systems and the deviation of the calculated values from experiment values are low.

Screening of potential hydrate promoter/inhibitor species is essential in the investigation of clathrate hydrates in many areas of industrial interest. However, experimental analyses do not yield sufficient information to determine whether molecular size, dipole moment, molecular mass, or any other parameters influence the thermodynamic stability of clathrate hydrates in general. The present contribution employs a mutual information-based nonparametric statistical analysis to identify trends in a multivariate data set for 21 clathrate hydrate formers. It is showed through the introduction of a simple correlation that prediction of the heat of dissociation of a clathrate hydrate may be sufficient to predict the entire phase equilibrium curve above the ice point. The dipole moment and molecular volume of hydrate forming species influence the dissociation pressure curve, and distinctive behaviours may be observed for cyclic gas species as compared to non-cyclic species.

The present work focussed on application of the environmental friendly 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([BMIM]+[Tf2N]−) ionic liquid for the separations of (alkane/aromatic), (alkane/alk-1-ene), (cycloalkane/aromatic) and (water/alkan-1-ol) using gas-liquid chromatography (GLC) technique. In this reason the activity coefficients at infinite dilution, γ13∞, for 31 organic solutes (alkanes, cycloalkanes, alkenes, alkynes, aromatics, alkanol and ketones) and water in ionic liquid were measured at temperatures of (323.15, 333.15, 343.15, 353.15 and 363.15) K. Stationary phase loadings of (42.83 and 68.66) % by mass were used to ensure repeatability of measurements. Density and viscosity values were measured to confirm the purity of ionic liquid. Partial molar excess enthalpies at infinite dilution, ΔH1E , ∞, were also determined. The selectivities, Sij∞, and capacities, kj∞, were determined for the above separations. The separating ability of the investigated ionic liquid was compared with previously investigated ionic liquids and industrial solvents such as sulfolane, n-methyl-2-pyrrolidine (NMP) and n-formylmorpholine (NFM).

In this paper, the influence of alkyl group as well as temperature on interactions between carboxylic acid and acetonitrile were examined using thermodynamics technique. The carboxylic acid used in this study was acetic acid and propionic acid. To explore the utility of carboxylic acid and acetonitrile, we have carried out the interaction studies of carboxylic acid with acetonitrile using density, ρ, and sound velocity, u, measurements of acetic acid, propionic acid, acetonitrile, and their binary systems {acetic acid or propionic acid (x1) + acetonitrile (x2)} as function of temperature. The excess molar volumes, V m E , isentropic compressibility, κs, and deviation in isentropic compressibility, Δκs, were calculated from thermophysical properties, respectively which provide information about the intermolecular interactions as well as the influence alkyl group and temperatures that occurs between carboxylic acid and acetonitrile mixtures. The Redlich–Kister polynomial equation was used to fit the thermodynamics properties to test the experimental data. These results are useful for describing the intermolecular interactions; developing structure–property correlation and molecular modeling that exist between the carboxylic acid and acetonitrile mixtures.

The solubility of complex triterpenes Lup-20(29)-ene-3β,28-diol (betulin) and (8R,9S,13S,14S)-3-hydroxy-13-methyl-6,7,8,9,11,12,13,14,15,16-decahydrocyclopenta[a]phenanthren-17-one (estrone) in numerous common solvents were determined by combined thermal gravimetry and digital thermal analysis (TGA/DTA). The measurements were conducted at atmospheric pressure and within the temperature range of T = (293.2 to 328.2) K. Melting point and enthalpy of fusion data of the solutes considered were also determined by DTA/TGA. The measured values were modelled using the Non-Random Two Liquid (NRTL) and Tsuboka–Katayma modified Wilson activity coefficient models which incorporated polynomial temperature dependence. The models provided a very good correlation of the experimental values in most cases.

One of the barriers against application of ionic liquids (ILs) for industrial separations is their relatively high viscosity. The viscosity of the IL can however be decreased by inserting the fluorinated moieties into the anion structure. Hence, if one could find a relationship between chemical structure, temperature, and viscosity one could design fluorine-containing ILs (F-ILs) with desired specifications. In this communication, two extensive dataset of F-ILs were gathered; one with reliable sources consisting of 863 experimental viscosities for 85 F-ILs, and the other including unreliable sources consisting of 1160 experimental data points for 332 F-ILs. Using the reliable dataset an efficient group contribution (GC) model was developed, which employs a total of 35 functional groups to estimate the temperature-dependent viscosities of F-ILs. The proposed GC model produced a low average absolute relative deviation (AARD) of 3.23%, root-mean-square error (RMSE) of 0.19, and coefficient of determination (R 2 ) of 0.977. The other model developed using the second database only parameterized in supplementary materials.

In this communication, the effect of tetrabutyl ammonium nitrate (TBANO 3 ) on CO 2 , CH 4 , or N 2 hydrate was studied. Hydrate dissociation conditions for CO 2 + TBANO 3 + water, CH 4 + TBANO 3 + water and N 2 + TBANO 3 + water were investigated at different concentrations of TBANO 3 , viz. (0.05, 0.10, and 0.15) mass fraction, and over a temperature and pressure range of T = (275.1 to 285.1) K and (1.21 to 7.27) MPa, respectively. The results show that the presence of TBANO 3 causes the phase equilibrium curve to be shifted to moderate conditions (lower pressure and higher temperature), especially at higher concentrations of TBANO 3 .

Clathrate hydrate dissociation data were measured for systems comprising of refrigerants (R134a, R410a and R507) + water + MgCl 2 at varying salt concentrations. The ternary system for R134a + water + MgCl 2 was measured at salt concentrations of (0.259, 0.546, and 0.868) mol.kg −1 in the temperature range of (277.1–283) K and a pressure range of (0.114–0.428) MPa. Hydrate measurements for the {R410a or R507} + water + MgCl 2 systems were measured at salt concentrations of (0.259 and 0.546) mol.kg −1 in the temperature range of (274.3–293) K and a pressure range of (0.154–1.421) MPa. The isochoric pressure-search method was used to measure the hydrate dissociation data. This study is a continuation of previous investigations which focused on obtaining hydrate dissociation data for R134a, R410a and R507 refrigerants in NaCl and CaCl 2 aqueous solutions. The measured hydrate dissociation data can be used to design industrial wastewater treatment and desalination processes. The results show that the effect of salt concentration on hydrate formation is smaller for MgCl 2 aqueous solutions compared to CaCl 2 and NaCl as salt concentration increases. Modelling of the measured data is performed using a combination of the solid solution theory of van der Waals and Platteeuw, the Aasberg–Petersen et al. model, and the Peng–Robinson equation of state with classical mixing rules. The model is in good agreement with the measured hydrate dissociation data.

In this communication, a corresponding states-based model for the calculation/estimation of the gas compressibility factor ( z -factor) of natural gasses is proposed. The method applies the gene expression programming (GEP) algorithm. The parameters of the new model comprise the pseudo-reduced pressure and pseudo-reduced temperature. For assessing the performance and accuracy of the developed model, several statistical and graphical error analyses have been applied simultaneously. Additionally, comparisons have been made between this method and the most widely-used correlations and equations of state (EoS) available in the literature. Various statistical parameters are also used to evaluate the validity and the predictive capability of the newly developed method. Furthermore, the Leverage approach (Williams plot) is used to determine the realm of prediction capability of the new z-factor model and to detect any probable erroneous data points. The results obtained demonstrate that the newly proposed model is more reliable and more effective than the empirical models and EoS methods for prediction of z -factors of natural gasses.

It has been shown in literature that gas hydrates can be used in sugar milling processes as a means of increasing the solids content in aqueous carbohydrate systems. In order to fully understand the practicalities of using gas hydrate technology in this regard, it is important to accurately know hydrate formation/dissociation conditions. The aim of this study is to obtain hydrate dissociation conditions of various refrigerant hydrates in the presence of sucrose aqueous solutions. The data will be used to design an aqueous solution separation process. The measurements were performed using the isochoric pressure search method with a newly developed high-pressure apparatus. New experimental gas hydrate systems measured include R134a + water + (12 or 15) weight percent sucrose, R410a + water + (12 or 15) weight percent sucrose, and R507 + water + (12 or 15) weight percent sucrose. Measurements were undertaken in the temperature range between (276.5 and 289.1) K and pressures ranging from (0.136–0.962) MPa. In addition, a sucrose sample supplied by the Sugar Milling Research Institute (SMRI) in Durban, South Africa was also investigated. The results show that the presence of sucrose exhibits an inhibition effect on hydrate formation. This is seen by the shift of the equilibrium phase boundary to either higher pressures or lower temperatures. Additionally, through measurements performed on the SMRI sample it can be seen that the presence of additional carbohydrates (glucose and fructose) in the system increases the effect of inhibition on hydrate formation. A thermodynamic model based on the van der Waals–Platteeuw solid solution theory was used to model the hydrate dissociation conditions. A good agreement between the experimental measurements and the model was observed.

The phase behavior of tetrabutylphosphonium bromide (TBPB) semi-clathrates with three gases, viz. CO2, CH4 or N2 was investigated in this study. The measurements were performed using a static high pressure cell using the isochoric pressure search technique. In order to determine the thermodynamic stability conditions of the semi-clathrates, the equilibrium data were measured at various concentrations of TBPB, viz. (0.05, 0.075, 0.10, 0.15, and 0.20) mass fraction TBPB. Measurements were undertaken in the temperature range of (279.3–291.4) K and in the pressure range of (1.06–7.79) MPa. The results indicate that TBPB has a promotion effect on semi-clathrate hydrate formation for the pure gas systems under consideration.

In this study, the Guggenheim equation was used to estimate the critical temperature ( T c ) of 106 ionic liquids using experimental surface tension data as inputs. A group contribution (GC) and a Quantitative Structure-Property Relationship (QSPR) model were also developed to correlate/predict the T c of ionic liquids. It was shown that a lack of sufficiently large database for T c leads to the development of models with low prediction capability. The models output as well as the T c values estimated from the surface tension data were compared with the critical temperatures calculated by the Valderrama et al. method. The results show that the Valderrama et al. method produces different data values compared with the values calculated by the Guggenheim equation. Neither the GC, QSPR, nor Valderrama's method is capable of reliable prediction of the T c of ionic liquids. Consequently, the calculated T c values are not reliable enough to be used in the development of corresponding state models for prediction of other thermophysical properties of ionic liquids. Any usage of critical properties of ionic liquids should be done with a serious caution.

The (vapour + liquid) equilibrium (VLE) was measured for the (carbon dioxide + n-hexane) binary system at temperatures between T = (303.1 and 323.1) K. In addition, VLE and (vapour + liquid + liquid) equilibria (VLLE) were determined for the (trifluoromethane + n-hexane) binary system at temperatures between T = (272.9 and 313.3) K and pressures in the range of P = (1.0 to 5.7) MPa. Measurements were undertaken in a static-analytic apparatus, with verification of experimental values undertaken using a static-synthetic equilibrium cell to measure bubble point pressures at several compositions. The phase equilibrium results were modelled with the Peng–Robinson equation of state with the Mathias–Copeman alpha function, coupled with the Wong–Sandler mixing rules. Regression of the data was performed with the NRTL and the UNIQUAC activity coefficient models with the Wong–Sandler mixing rules, and the performance of the models was compared. Critical loci for both systems were estimated, using the calculation procedures of Ungerer et al. and Heidemann and Khalil. For the (trifluoromethane + n-hexane) system, liquid–liquid immiscibility was experienced at the lowest temperature measured (T = 272.9 K). At higher temperatures, no immiscibility was visible during the measurements; however, the models continued to predict a miscibility gap.

In this study, experimental hydrate dissociation data for krypton in the presence of aqueous solutions of TBAB at varying concentrations of 0, 0.05, 0.10 and 0.20 mass fraction TBAB were measured. The measurements were undertaken in the temperature range of (274.1 to 297.1) K and pressures ranging from (0.22 to 11.97) MPa. In addition, semi-clathrate hydrate dissociation data for the TBAB + water system at a pressure of 99.8 kPa and at various TBAB concentrations of 0.05, 0.10, 0.20 and 0.30 mass fractions were measured. The isochoric pressure-search method was used to undertake the measurements. The purpose of this study was to investigate the effect of TBAB aqueous solution on krypton hydrates. The results reveal that the TBAB aqueous solutions with concentrations of 0.05, 0.10 and 0.20 mass fractions show a drastic promotion effect on the krypton hydrate causing a shift of the P - T equilibrium line to lower pressures and higher temperatures. In addition, increasing the TBAB concentration increases its promotion effect. The hydrate dissociation conditions for krypton + water + TBAB system were represented using a model based on the work of Chen and Guo, (Chem. Eng. J. 71 (1998) 145–151) and Joshi et al. (J. Nat. Gas Chem. 21 (2012) 459–465). The model results show a satisfactory agreement with the experimental data, with an absolute relative deviation (ARD%) below 0.3%.

Isothermal vapour–liquid equilibrium data were measured for ethene + perfluoro-n-octane mixtures at five temperatures in the 293–353 K range, and pressures up to 8 MPa. Experimental P–x–y data were measured using an apparatus based on the “static–analytic” method. The experimental data were correlated with a model comprising the Peng–Robinson equation of state with either the classical mixing rule or the Wong–Sandler mixing rule coupled with the Non-Random Two-Liquid activity coefficient model. The model gave good representation of the experimental data.

A polyvinylpyrrolidone (PVP) polymer has been shown to interact with the ionic liquids (ILs), 1-butyl-3-methylimidazolium bis(trifluromethylsulfonyl)imide [BMIM][Tf2N], 1-butyl-3-methylimidazolium methylsulphate [BMIM][MeSO4], and 1-ethyl-3-methylimidazolium-n-octylsulphate [EMIM][OS]. Ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR) and confocal Raman spectroscopy have revealed that these ILs have the ability to interact with the polymer. The Density Functional Theory (DFT) calculation has been performed to optimize the ILs-PVP systems. The results show that there are several H-bonds between ILs and PVP. This study delivers the mutual effect of the polymer and ILs that may create many theoretical and experimental opportunities.