Dissertations / Theses on the topic 'Activity coefficients at infinite dilution'

The aim of this investigation was to develop and test a theory that allowed for the calculation of the activity coefficients at infinite dilutions (l' ~ 3) from G.L.C. measurements using moderately volatile solvents. The solvents chosen for study were straight chained (Cs to C7) and cyclic (Cs, C6 and benzene) liquid hydrocarbons using cis- and trans-decahydronaphthalene (decalin) as the stationary liquid phase (solvent). The systems were studied at two different temperatures, 283.15 K and 298.15 K. The solutes were n-pentane~ n-hexane, n-heptane, cyclopentane, cyclohexane and benzene. This method for the determination of activity coefficients has the advantage of being able to work at infinite dilution, whereas in other techniques, extrapolation to infinite dilution of finite-concentration data is necessary. In addition solutes are separated from impurities when chromatographed so that only very small quantities of moderately pure material need be· used. However the technique is also limited since the solute studied (injected reagent) needs to be volatile, while the solvent (liquid stationary phase) should be involatile. The solvents chosen in this experiment (cis- and transdecalin) are moderately volatile which introduces many limitations since the theory developed for the determination of activity coefficients at infinite dilution is restricted to involatile solvents. However a novel method for working with moderately volatile solvents is developed by relating the loss of solvent to its partial pressure and modifying the existing theory. In the past the use of precolumns and/or saturators, coarse packing, small pressure gradients, and internal standards were used when working with volatile solvents. However employing this new method excludes the use of precolumns, saturators, or internal standards, and allows any type of packing and pressure gradient to be used. The calculated activity coefficients are compared with literature values, where the wor~ers employed G.L.C. techniques, and with predicted values. The activity coefficients calculated at both temperatures are used in the calculation of excess partial molar enthalpies. These results are compared with values obtained from finite concentration data by other workers.<br>Thesis (M.Sc.)-University of Natal, Durban, 1992.

The determination of limiting activity coefficients in liquid mixtures has become an important tool in chemical engineering. It has been investigated intensively during the past in order to find new alternatives and improved methods for its accurate detennination. The limiting activity coefficient is a fundamental thermodynamic quantity which measures the solution non-ideality and acts as a correction factor to deviations from Raoult's Law. This dissertation involves the determination of limiting activity coefficients using the inert gas stripping (IGS) technique only. It is considered to be the best method as it is a direct method involving exact concentrations of components in the mixtures encountered in industry. A comprehensive study of activity coefficients at infinite dilution for various systems, using the inert gas stripping (IGS) method has been undertaken. Various other methods and their suitability have also been discussed but preference is given to the superior quality of measurements obtained using the inert gas stripping technique. Extensive research has been conducted into the background and origination of the technique. Various improvements of the equilibrium cell designed by various authors for different types of systems have been outlined along with the various equations derived by the authors. The equipment was designed for use with the double-cell technique as well as the single-cell technique and in some cases both techniques were used. The techniques involve the use of a dilutor cell in which the highly diluted, volatile solute is stripped from a liquid solution using the inert gas nitrogen, introduced into the cell through capillaries and dispersed through the solution as small bubbles, at a constant flow rate. Analysis of the stripped solution is accomplished through the use of a gas chromatograph; the peak areas obtained from these analyses as well as the residence times and other system data such as temperature, pressure, mass and flow rate were used to compute the infinite dilution activity coefficient through the use of the various equations available in literature. The original equipment was designed for the use of the single cell technique by Soni (2004). Various modifications have been made to the equipment in order to measure limiting activity coefficients of more diverse systems with high accuracy. A major change to the equipment was the introduction of a second saturation cell of similar design to the dilutor cell. This enabled the determination of activity coefficients at infinite dilution of difficult systems i.e. systems where the solvent volatility is high and for higher order systems. The equipment was redesigned and built using ideas and improvements by previous researchers in the field and commissioned using test systems that have been classed as easy systems for this technique. The new equipment is now applicable to almost all systems, however good separation in the GC column could be a problem for complex systems. The determination of infinite dilution activity coefficients for one-component solute + onecomponent solvent systems and multi-component solvent systems were accomplished. The systems that were investigated consisted of a mixture of components of alkanes, alkenes, phenols and ketones, mostly in binary mixtures. Multi-component mixtures have also been investigated in the form of ternary systems involving a binary solvent mixture at varying concentrations, and a solute in order to show the diversity, uniqueness and efficiency of the IGS technique. Major variables affecting the system (the dilutor cell), namely the stripping gas flow rate and the dilutor cell temperature, were also investigated for all systems. Two test systems, cyclohexane in 1-methyl-2-pyrrolidone (NMP) and n-heptane in NMP were used to determine if the equipment is operating properly by comparing values obtained, to literature values where the inert gas stripping technique was used to determine the activity coefficients at infinite dilution. Another test system n-hexane in NMP was used to compare the two techniques, Le. the results of the single cell technique with the results of the double cell technique. The experimental results were thereafter compared to published literature values. Systems where the inert gas stripping technique has not been used to determine activity coefficients at infinite dilution were also investigated. These systems include 1-hexene in 0- cresol as well as the ternary systems '-hexene in various concentrations of NMP + o-cresol. A thorough literature survey has been completed and the relevant theory has been summarized. The validity of the equations proposed by Bao and Han (1995), Duhem and Vidal (1978), Leroi et a!. (1977), Hovorka and Dohnal (1997) and Krummen et al. (2000) for the determination of activity coefficients at infinite dilution were investigated. The experimental values obtained were consistent with literature values, with percentage errors of less than 1 % where the same equation was used to determine the limiting activity coefficient. Comparing limiting activity coefficients with the values obtained from other equations proposed by other authors mentioned above resulted in deviations no greater than 2.5 %, and where possible limiting activity coefficients were compared to values obtained from the single-cell technique. The theory section of this thesis covers all the various formulae (and where possible a summary of their derivation) used in the analysis of results. Some limiting activity coefficients for the systems involving n-heptane, n-hexane, n-hexene, cyclohexane, o-cresol and n-methyl-2-pyrrolidone under various experimental conditions have been reported making it readily available for use in other works. The effect of two major variables temperature and inert gas flow rate on the limiting activity coefficients with regard to all the systems studied have also been investigated and reported. This was also done in order to check that the data was reproducible. A sensitivity analysis was also performed in order to check the effect that certain measured variables would have on the limiting activity coefficient. These errors are estimated possible errors and may not exist at all, so not much consideration was given to this when reporting limiting activity coefficients for the various systems. The maximum error range for any given limiting activity coefficient as determined by the sensitivity analysis is ±11 %. The inert gas stripping technique is also extended to the determination of Hendry's constants. The actual values for the Hendry's constants were not determined but a comprehensive study of its determination was undertaken by Miyano et al. (2003) and summarized here. In addition the suitability and diversity of the inert gas stripping technique has been outlined, along with the advantages and disadvantages of the technique. The various designs of equilibrium cells have been outlined taking into account mass transfer considerations as proposed by Richon et al. (1980). The assumptions and limits of the method have also been outlined and must be taken into consideration when using the technique. A detailed description of the equipment setup and experimental procedure has been provided. The purpose, suitability, operation and applicability, of the various pieces of equipment used to make up the final equipment have been discussed in detail. Details for consideration when designing the equilibrium cells have also been provided.<br>Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2008.

博士<br>國立臺灣大學<br>化學工程學研究所<br>91<br>Knowledge of the infinite dilution activity coefficients (g¥) has many practical applications. It was used in solvent selection for traditional separation process such as extractive distillation. It was recently employed in calculating the solid solubility of supercritical extraction or the critical micelle concentration of surfactant systems. Extensive applications in commercially important complex polymer solutions like paints and coatings or pharmaceuticals make the study of g¥ essential. In this study, a regular solution model coupled with a Flory-Huggins equation was firstly employed to evaluate the solid solubility of heavy aromatics or biological compounds in supercritical carbon dioxide and various supercritical fluids. A relatively simple correlation for the model parameter was proposed to yield good calculated accuracy. Secondly, an activity coefficient model was developed on the basis of the lattice theory proposed by Aranovich and Donohue. With the modification of the local-composition expression, an m-AD model was derived which yields satisfactory results of the g¥ values on both aqueous and organic mixtures. Furthermore, applications of the m-AD model on phase equilibrium calculations were examined. Both vapor-liquid and liquid-liquid equilibria on fluid mixtures were investigated using the m-AD model with comparably good results as those from the traditional approaches. The m-AD model was further employed to evaluate the solid solubility in supercritical CO2 and the results are again feasible. Finally, the m-AD model was applied to calculate the critical micelle concentration (CMC) of the aqueous mixture containing the nonionic CiEj surfactant. With a generalized correlation, the CMC values are calculated in good agreement with the experimental data. In addition, the CMC values of the mixed surfactants in aqueous solution are precisely predicted using the m-AD model. A modified infinite dilution activity coefficient model based on the concept of the local-composition lattice fluid was proposed in this study. The m-AD model was applied not only to the calculation of the infinite dilution activity coefficient, the vapor-liquid and liquid-liquid phase equilibrium calculations, but also to the solid solubility in supercritical fluids and the CMC evaluations for the surfactant systems. It is demonstrated that the theoretically based m-AD model is a relatively simple method and is feasible to the engineering calculations.

Submitted in fulfillment of the requirements for the degree of Doctor of Technology: Chemistry, Durban University of Technology, Durban, South Africa, 2017.<br>The thermodynamic properties of mixtures involving ionic liquids (ILs) with organic acid (acetic acid or propanoic acid) or acetonitrile at different temperatures were determined. The ILs used were imidazolium-based: 1-ethyl-3-methylimidazolium ethyl sulphate [EMIM]+[EtSO4]-, 1-butyl- 3-methylimidazolium thiocyanate [BMIM]+[SCN]- and 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([BMIM]+[Tf2N]-. The ternary excess molar volume (V E ), isentropic compressibility (ks) and deviation in isentropic compressibility ( ks123 ) were determined for four ternary liquid mixtures of {[EMIM]+[EtSO4]- or [BMIM]+[SCN]− + acetic or propionic acid + acetonitrile} at different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15) K and at a pressure of 0.1 MPa with aid of the experimental density (ρ), speed of sound (u) data. The calculated data were correlated by using the Cibulka equation with the help of Redlich–Kister parameters obtained from fitting the Redlich–Kister equation for the corresponding binary systems. Furthermore, the density and speed of sound were also measured for eight corresponding binary systems at the same experimental conditions. The binary excess molar volume, isentropic compressibility and deviation in isentropic compressibility were also calculated for measured systems and fitted to the Redlich–Kister equation to obtain the Redlich–Kister parameters as well as to check the accuracy of measured data which were used to correlated experimental data using Cibulka equation. These results were discussed, in terms of how the sign and magnitude of thermodynamic functions were influenced by the addition of a third component to liquid systems. Also, the possible molecular and pair-wise interactions between component molecules and the effect of temperature on the thermophysical and thermodynamic properties were predicted. In addition, the work focussed on application of ([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. The activity coefficients at infinite dilution, , 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 E , measurements. Partial molar excess enthalpies at infinite dilution, H1 , were also determined. The selectivities, S , and capacities, k , were determined for the above separations. The separating ij j 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). The results obtained suggested that in general, the [BMIM]+[Tf2N]− had outperformed the conventional solvents such as sulfolane, NMP and NFM in terms of selectivity, while the [BMIM][Tf2N] had in general, performed better overall when the performance index was used for comparison.<br>D

Submitted in fulfillment of the academic requirements for the degree of Master of Engineering in Engineering, Durban University of Technology, Durban, South Africa, 2018.<br>Many separation processes in the chemical and petrochemical industries are energy intensive, and unfortunately, involve a range of solvents that are environmentally harmful and destructive. Alternative, sustainable separation techniques are desired to replace these conventional methods used in the separation of azeotropic as well as close-boiling mixtures, with the intention of reducing energy costs and adverse impact on the environment. In the present study, a new class of solvents called deep eutectic solvents (DESs) of Type III were investigated as alternatives to conventional solvents currently employed in separation processes. DESs are classified as ‘green’ solvents because of a range of favourable properties including lower cost, desirable solubility properties and reduced environmental impact (Abbott et al., 2003b; Smith et al., 2014). The infinite dilution activity coefficients (IDACs) values of 24 solutes – including alk-1-anes, alk-1-enes, alk-1-ynes, cycloalkanes, alkanols, alkylbenzenes, heterocyclics, esters, and ketones – were measured at 313.15, 323.15, 333.15 and 343.15 K by gas-liquid chromatography (GLC) in DESs. The four investigated DESs were as follows: 1) Tetramethylammonium chloride + Glycerol (DES1); 2) Tetramethylammonium chloride + Ethylene Glycerol (DES2); 3) Tetramethylammonium chloride + 1,6 Hexanediol (DES3); and 4) Tetrapropylammonium bromide + 1,6 Hexanediol (DES4). This work focused on the performance of DESs as extractive solvents for selected azeotropic and close-boiling binary mixtures. The two key performance criteria for these extractive solvents – selectivity and capacity – were determined from experimental infinite dilution activity coefficients (IDACs) of various solutes. The effect of solute molecular structure on IDAC values was investigated. Moreover, the effect of varying the hydrogen bond donors (HBDs) in DESs on IDAC values was examined. Partial excess molar enthalpies at infinite dilution were determined from the experimental IDAC data. Moreover, common industrial separation problems were selected to investigate DES potential to separate various mixtures by determining selectivity and capacity at infinite dilution. The results obtained in this study indicate that the use of a long carbon chain HBDs greatly decreases miscibility of DESs with organic solutes. For systems such as n-heptane - toluene, acetone - ethanol, cyclohexane - benzene and n-hexane - benzene systems, DES4 was the best solvent regarding the separation performance index. However, further investigation for DES4 by measurements of vapour-liquid equilibria (VLE) and liquid-liquid equilibria (LLE) data is suggested, as these data would provide additional pertinent information regarding the separation of such mixtures using DES4. The data produced from this study can be used to extend the applicability range of predictive models such as Universal Quasi- Chemical Functional Group Activity Coefficients (UNIFAC) and modified UNIFAC (Do) which are already incorporated in some chemical engineering process simulators.<br>M

Dissertation submitted in fulfilment of the requirements for the Masters Degree in Technology: Chemistry, Durban University of Technology, 2009.<br>The activity coefficients at infinite dilution ( γ13 ) were calculated for alkanes, alkenes, cycloalkanes, alkynes, ketones, alcohols and aromatic compounds from gas liquid chromatography (glc) measurements at three temperatures (303.15 and 313.15 and 323.15) K. The γ13 values were calculated from the retention data for two ionic liquids (ILs) with the same cation but different anions. The ionic liquids: [methyltrioctylammonium bis(trifluoromethylsulfonyl)imide and methyltrioctylammonium thiosalicylate] were used as the stationary phase. The γ13 data for methyltrioctylammonium thiosalicylate were higher than for methyltrioctylammonium bis(trifluoromethylsulfonyl)imide. For each temperature and each ionic liquid, γ13 values were determined for two columns and the average γ13 values were used for the calculation of the partial molar excess enthalpies at infinite dilution, H E 1 Δ , using the Gibbs-Helmholtz equation. Graphs of In γ13 vs 1/T were plotted to determine H E 1 Δ at T = 303.15 K. The selectivity, S12 , value for the hexane/benzene separation was calculated from the ratio of the avarage γ13 values to determine the suitability of the ILs as an entrainer for extractive distillation in the separation of aromatic and aliphatic compounds.The S12 values were also compared to the literature values for other ionic liquids. It was found that the longer chain alkyl group attached to the cation or anion gave lower S12 values. Both ILs have S12 values greater than one and in theory can be used as an entrainer for the hexane/ benzene separation. The capacities at infinite dilutions, k1 , were also calculated from the inverse of the avarage γ13 values for each IL at each temperature.

Acetylpropionyl (2,3-pentanedione) and diacetyl (2,3-butanedione) are by-products of sugar manufacture. Both diketones have many uses, mainly food related. Vapour-liquid equilibrium data and infinite dilution activity coefficients are required to design purification processes for these chemicals. A review of available experimental methods revealed that the vapour and liquid recirculating still is most appropriate when both isobaric and isothermal VLE are required. The low-pressure dynamic still of Raal and Muhlbauer (1998) used in this study incorporates many features to ensure that measurements are of excellent quality (as demonstrated by Joseph et al., 2001). VLE measurements were made for the following systems: • Acetone with diacetyl at 30 C, 40 C, 50 C and 40 kPa • Methanol with diacetyl at 40 C, 50 C, 60 C and 40 kPa • Diacetyl with 2,3-pentanedione at 60 C, 70 C, 80 C and 40 kPa • Acetone with 2,3-pentanedione at 50 C, 30 kPa and 40 kPa. All the systems, except for methanol with diacetyl, displayed close to ideal behaviour. This was expected as they are mixtures of ketones. Solution thermodynamics allows one to perform data reduction of the measured VLE data to ensure accurate extrapolation and interpolation of the measurements. Furthermore, the quality of the data can be judged using thermodynamic consistency tests. The data were represented by the Gamma-Phi approach to VLE (the preferred method for low-pressure VLE computations). The two-term virial equation of state was used to account for vapour phase non-ideality. Second virial coefficients were calculated by the method of Hayden and 0'Connell (1975). The liquid phase non-ideality was accounted for by the Wilson, NRTL or UNIQUAC models. The best fit models are proposed for each system, as are parameters as functions of temperature for the isobaric data. The data were judged to be of high thermodynamic consistency by the stringent point test (Van Ness and Abbott, 1982) and the direct test (Van Ness, 1995) for thermodynamic consistency. The data sets were rated, at worst, "3" on the consistency index proposed by Van Ness (1995). A rating of "I" is given for a perfectly consistent data set and "10" for an unacceptable data set. For the system acetone with 2,3-pentanedione, isobars at 30 kPa and 40 kPa were measured. The results from the reduction of the 30 kPa set were used to accurately predict the 40 kPa data set. Infinite dilution activity coefficients were measured by the inert gas stripping method (based on the principle of exponential dilution). In order to specify the appropriate dilutor flask height (to ensure equilibrium is achieved), mass transfer considerations were made. These computations ensured that the gas phase was in equilibrium with the liquid phase at the gas exit point. The following infinite dilution activity coefficients were measured: • Acetone in diacetyl at 30 C • Methanol in diacetyl at 40 C • Diacetyl in 2,3-pentanedione at 60°C • Acetone in 2,3-pentanedione at 50 C. The ketone mixtures, once again, displayed close to ideal behaviour.<br>Thesis (M.Sc.)-University of Natal, Durban, 2003.

PART I: This work is part of an investigation to determine activity coefficients at infinite dilution (1'73) of hydrocarbons dissolved in the industrially important polar solvent tetrahydrothiophene-l, l-dioxide (sulfolane), by medium pressure gas liquid chromatography (g.l.c.). In this work the activity coefficients at infinite dilution for a series of l-alkenes (C6-CS) , l-alkynes (C6-CS) , and cycloalkanes (C7 and Cs) have been measured in the polar solvent, sulfolane, at 303.15 K and 313.15 K. The activity coefficients of some of the solutes discussed in this work would be difficult to determine by any other method because of their low solubility in sulfolane. The mixed second virial coefficients used in this work were determined assuming the principle of corresponding states, the Hudson and McCoubrey combining rules for T~2' the Lorentz rule for V~2' and the McGlashan-Potter equation. PART II: Unrefined sugar contains organic colour material originating In the sugarcane or formed during the extraction and purification processes. Sugar colour must be within the limits of acceptability for direct or indirect consumption. In this work, a cost effective technique to separate colourants from sugar through a sucrose packed medium pressure chromatographic column was investigated. Three dimensional perspective plots of wavelength/absorbance/time were developed to provide insight into the nature of the sugar colourants and to provide a means of investigating various decolourisation systems. In addition to the above experiment a procedure was developed to remove colourant species from unrefined sugar samples and from samples taken during the refining process for chemical analysis. In this work only one technique - gas chromatography-mass spectroscopy was used to identify the species.<br>Thesis (M.Sc.)-University of Natal, Durban, 1996.

Infinite-dilution fugacity coefficients were obtained for the binary system fluorene/phenanthrene at thirteen temperatures by fitting total pressure across the entire mole fraction range by a computer routine. A thermodynamically consistent routine, that allowed for both positive and negative pressure derivations from the ideal values, was used to correlate data over the full mole fraction range from 0 to 1. The four-suffix Margules activity coefficient model without modification essentially served this purpose since total pressures and total pressure derivatives with respect to mole fraction were negligible compared to pressure measurement precision. The water/ethanol system studied by Kolbe and Gmehling and binary systems studied by Maher, Srivastava and Smith comprised of aniline, chlorobenzene, acetonitrile and other polar compounds were fit for total pressure across the entire mole fraction range for binary Vapor-Liquid-Equilibria (VLE) using the rigorous, thermodynamically consistent expression derived by Ibl and Dodge from the Gibbs-Duhen Relation. Data correlation was performed using a computer least squares procedure. Infinite-dilution fugacity coefficients were obtained using a modified Margules activity coefficient model which gives residual values of x$\sb1$ dly$\gamma\sb1$ + x$\sb2$ dln$\gamma\sb2$ across the mole fraction range that lie between the value of vd$\Pi$/dx$\sb1$/RT at x$\sb1$ = 0 and x$\sb1$ = 1. x$\sb1$ and $\gamma\sb1$ and x$\sb2$ and $\gamma\sb2$ are the mole fraction and activity coefficient of components 1 and 2 respectively. v is the mixture liquid molar volume, $\Pi$ is total pressure, R is the ideal gas constant, and T is temperature in absolute units. This correlational procedure, a modified Margules model, yielded infinite-dilution fugacity coefficients differing from the non-rigorous Margules model (derived for a binary at constant pressure) by a few percent but in some cases by as much as ten percent. The modified version is necessary in fitting binary total pressure versus mole fraction data to an expression totally consistent with Gibb's Phase Rule. Its application implies that the derivative of pressure with respect to mole fraction may affect the values of activity coefficients determined, especially at either infinite-dilution axis where the absolute value of this derivative is greatest.

Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná<br>This work discusses the potential of imidazolium-based ionic liquids as potential in the fractionation of terpene mixtures, also giving information relevant to study other separation processes such as the desulfurization and denitrification of fuel oils. Besides pure [C12mim]Cl, the equimolar mixture [C4mim][C12mim]Cl of ionic liquids was also tested. The separation capacity between solutes and ionic liquids can be calculated from infinite dilution activity coefficients, measured experimentally for 40 solutes; water, common organic solvents and terpenes in both ionic liquids using inverse gas chromatography, in the temperature range of 333.15 to 423.15 K. The values for the activity coefficients at infinite dilution are very small for terpenes and terpenoids, indicating a strong interaction, possibly due to the high basicity of the anion and the high apolarity of the cation. Selectivities were obtained for hypothetical binary mixtures containing α-pinene oxide but showing, in general, low capacities. However, preliminary results showed that the combination of two ionic liquids could present better selectivity values than pure ionic liquids, which is an open area to be explored.<br>Este trabalho discute o potencial dos líquidos iônicos à base de imidazólio como potenciais agentes de separação no fracionamento de misturas de terpenos, também fornecendo informações relevantes para o estudo de outros processos de separação, como a dessulfurização e desnitrificação de óleos combustíveis. Além do [C12mim]Cl puro, a mistura equimolar [C4mim][C12mim]Cl de líquidos iônicos foi também testada. A capacidade de separação entre solutos e líquidos iônicos pode ser calculada a partir de coeficientes de atividade de diluição infinitos, medidos experimentalmente para 40 solutos; água, solventes orgânicos comuns e terpenos em ambos os líquidos iônicos usando cromatografia gasosa inversa, na faixa de temperatura de 333,15 a 423,15 K. Os valores dos coeficientes de atividade a diluição infinita mostraram-se muito baixos para terpenos e terpenóides, indicando uma forte interação desses com os líquidos iônicos, possivelmente devido à alta basicidade do ânion e à alta apolaridade do cátion. Seletividades foram obtidas para misturas binárias hipotéticas contendo óxido de α-pineno, mas associadas, em geral, com baixa capacidade. No entanto, resultados preliminares mostraram que a combinação de dois líquidos iônicos poderá apresentar melhores valores de seletividade do que líquidos iônicos puros, que é uma área de investigação a ser explorada.

Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná<br>The family of ionic liquids can provide safer, efficient and more sustainable alternative solvents than those commonly used. In this work, 1-butyl-3-methylimidazolium acetate (BmimAc) was the selected ionic liquid to be studied as a separation agent in different liquid-liquid extraction problems with terpenes and terpenoids. After separation, it is important to devise a strategy to recover the IL and minimize costs. To do so, infinite dilution activity coefficients of water and 44 solutes belonging to different families of organic compounds, were measured in the ionic liquid by gas chromatography. This ionic liquid showed strong interaction with polar solutes like alcohols and linalool, for which low values of activity coefficients at infinite dilution were obtained. Concerning the system limonene/linalool (compounds used in biodegradable solvents and perfumery industries), this IL showed the best values of capacity and selectivity, calculated through activity coefficients. However, it was not a good separation agent of the mixture α–pinene/β–pinene (used in used in medications with antifungal action). Besides that, the solid-liquid equilibria phase diagram was studied by differential scanning calorimetry (DSC), by measuring the freezing point depression of water caused by the addition of 1-butyl-3-methylimidazolium acetate. The methodology was tested first by measuring the freezing point of aqueous solutions of NaCl, CaCl2, 2-propanediol and 1-ethyl-3-methylimidazolium acetate (EmimAc). The values obtained in this work agreed with literature, except for the 1-ethyl-3-methylimidazolium acetate. So, further tests need to be carried out using other methodologies. Through the measurement of freezing point curves, important data were obtained concerning the 1-butyl-3-methylimidazolium acetate (BmimAc)+ water interactions. Thus, crystallization is a possible process for separating ILs from water. This work offers a solution to separate the system limonene/linalool and then recovery the IL through freezing point depression of water/BmimAc once that was possible freeze the water.<br>A família de líquidos iônicos pode fornecer solventes alternativos mais seguros, eficientes e mais sustentáveis do que os comumente usados. Neste trabalho, acetato de 1-butil-3-metilimidazólio (BmimAc) foi o líquido iônico selecionado para ser estudado como um agente de separação em diferentes problemas de extração líquido-líquido com terpenos e terpenóides. Após a separação, é importante conceber uma estratégia para recuperar o LI e minimizar os custos. Para isso, foram medidos coeficientes de atividade a diluição infinita de água e 44 solutos pertencentes a diferentes famílias de compostos orgânicos, no líquido iônico, por cromatografia gasosa. Este líquido iônico mostrou forte interação com solutos polares como álcoois e linalol, para os quais foram obtidos baixos valores de coeficientes de atividade em diluição infinita. No que diz respeito ao sistema limoneno / linalol (compostos utilizados como solventes biodegradáveis e na indústria de perfumaria), este IL mostrou os melhores valores de capacidade e seletividade. No entanto, não foi um bom agente de separação da mistura α-pineno / β-pineno (usados em medicamentos com ação anti-fungica). Além disso, o diagrama de fases de equilíbrio sólido-líquido foi estudado por calorimetria diferencial de varredura (DSC), medindo a depressão do ponto de congelamento da água causada pela adição de acetato de 1-butil-3-metilimidazólio. A metodologia foi testada primeiro medindo o ponto de congelamento de soluções aquosas de NaCl, CaCl2, 2-propanodiol e acetato de 1-etil-3-metilimidazólio (EmimAc). Os valores obtidos neste trabalho concordam com a literatura, exceto o acetato de 1-etil-3-metilimidazólio. Portanto, testes adicionais precisam ser realizados usando outras metodologias. Através da medição das curvas do ponto de congelamento, foram obtidos dados importantes sobre as interações 1-butil-3-metilimidazólio + água. Assim, a cristalização é um processo possível para separar ILs da água. Este trabalho oferece uma solução para a separação do sistema limoneno/linalol e a recuperação do LI usado no sistema por meio do abaixamento do ponto de congelamento da água em contato com o BmimAc, uma vez que foi possível cristalizar a água da mistura.