Physical properties of binary mixtures : ionic liquids + alcohols

Information on the interactions between ionic liquids and molecular solvents are essential for the understanding of the function of ionic liquids in related procedures, and excess properties are sensitive probe for studying these interactions. In this paper, physical properties such as densities and speeds of sound of the binary systems containing 1–propyl–4 methylpyridiniumbis(trifluoromethylsulfonil)imide and 1propyl–4–methylpyridiniumbis(trifluoromethylsulfonil)imide, ethanol and propanol, over the whole composition range were measured at T=(298.15, 308.15, 318.15) K and at atmospheric. These data were used to calculate the corresponding derived properties such as excess molar volumes and excess molar isentropic compressions, which were fitted with the Redlich-Kister equation. For the studied systems, the excess molar volume values show a sinusoidal behaviour with a minimum at high concentrations of alcohol due to changes from negative to positive values when the alcohol´s alkyl chain length increases. The excess molar isentropic compression values are negative over the whole composition range and presenting also a minimum at high concentrations of alcohol. It is possible observed that an increase of the temperature causes that the negative excess molar volume and excess molar isentropic compression values for the alcoholic mixtures deviate more from ideality.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

El uso de nuevos disolventes para la extracción de compuestos fenólicos presentes en las aguas residuales industriales

The development of industrial activity has associated a considerable increase in the volume of wastewater that, depending on their source, may contain large amount of organic and / or inorganic substances in concentrations which are harmful to the environment. Among these substances are the phenols, highly polluting substances and present in a large number of industrial activities (paper, food, photography, paints and explosives industries, synthesis of pharmaceuticals, petrochemical processes...). The removal of these compounds from wastewater streams before discharge is fundamental to the environmental protection. In this way, the Spanish legislation on industrial emissions limits the content of phenols in the wastewater to a maximum of 1 mg /l. The techniques used to remove or reduce the content of phenolic compounds in aqueous streams are biodegradation, thermal decomposition, and absorption, but none of them is effective when the wastewater contains a high concentration of phenols. Regarding the methods for liquid extraction with solvents, one of the main advantages is that they allow treating wastewater streams containing a high concentration of phenols. However, the more important limitation is that the solvents used in traditional liquid-liquid extraction are usually volatile organic compounds (VOCs), which are toxic, flammable and, in many cases, highly polluting substances. Therefore, it is desirable to consider alternative solvents that are equally effective but cleaner and more friendly with the environment. In this way, in recent years ionic liquids (ILs) and deep eutectic solvents (DESs) have attracted much attention from the scientific community due in particular to their combination of unique characteristics that make a difference with the conventional solvents. In particular their negligible vapor pressure and their physicochemical properties, such as polarity, viscosity and affinity for many organic and inorganic compounds, make them potential candidates for their use in multiphase systems as separation agents. Within this context, the main objective of this project is the application of hydrophobic ILs and DESs as extraction agents in the removal/reduction of phenol and its derivatives compounds (2-methylphenol, 2,4-dimethylphenol, 4-chlorophenol, 2-chlorophenol, 4-nitrophenol, 2,3-dichlorophenol, 2.4-dichlorophenol, pentachlorophenol, 2-benzyl-4-chlorophenol, etc.) present in wastewater streams generated at industrial level. This will require performing a solubility study of different ILs with the phenolic compounds, as well as the phase equilibria of ternary systems IL or DES + phenolic compound + water. These results will allow us to select the more appropriated solvent, which can perform an effective removal of phenolic compounds from water. Once selected the best solvent that allow to carry out an effective extraction, the next step will be its application to aqueous mixtures formed by a large number of phenolic compounds, in order to approach, insofar as possible, the real behavior of a residual stream generated in industry. With all these experimental data, the process simulation using commercial software will be carried out and the continuous extraction process at lab scale will be performed.El desarrollo de la actividad industrial llevado a cabo en las últimas décadas lleva asociado, en muchos casos, un aumento considerable del volumen de aguas residuales que, dependiendo de su procedencia, pueden contener gran cantidad de sustancias orgánicas y/o inorgánicas en concentraciones perjudiciales para el medioambiente (MA). Entre estas sustancias se encuentran los fenoles, sustancias altamente contaminantes y presentes en un gran número de procesos industriales (industria papelera, agroalimentaria, farmacéutica, petroquímica...) La eliminación de estos compuestos de las corrientes de aguas residuales antes de su vertido es fundamental para la protección del MA. En este sentido, la legislación española sobre vertidos industriales limita el contenido de fenoles en el agua residual a un valor máximo de 1 mg/l. Las tecnologías más utilizadas para eliminar o reducir el contenido de fenoles en corrientes acuosas son la biodegradación, la descomposición térmica y la absorción, pero ninguna de ellas parece ser eficaz cuando la corriente de agua residual presenta altas concentraciones de fenoles. La extracción líquida con disolventes tiene como principal ventaja que permite tratar corrientes de aguas residuales que contengan una elevada concentración de fenoles. Sin embargo, una de las principales limitaciones es que los disolventes utilizados en los sistemas tradicionales de extracción líquido-líquido suelen ser compuestos orgánicos volátiles, los cuales son tóxicos, inflamables y, en muchos casos, altamente contaminantes. Por lo tanto, es importante explorar disolventes alternativos que sean igualmente eficaces pero más limpios y respetuosos con el MA. En este sentido, en los últimos años, los líquidos iónicos (LI) y más recientemente los solventes eutécticos de bajo punto de fusión (DES) han acaparado la atención de gran parte de la comunidad científica debido, especialmente, a que poseen una combinación de propiedades únicas que los diferencian de los disolventes convencionales. En particular, su presión de vapor despreciable y sus propiedades fisicoquímicas, como la polaridad, viscosidad y la afinidad por muchos compuestos orgánicos e inorgánicos, los convierten en posibles candidatos para su utilización en sistemas multifásicos como agentes de separación. En esta línea, el objetivo principal de este proyecto consiste en la aplicación de LI hidrofóbos y de DES como agentes de extracción en la eliminación/reducción del fenol y sus compuestos derivados (2-metilfenol, 2,4-dimetilfenol, 2-clorofenol, 4-nitrofenol,...) presentes en las corrientes de aguas residuales generadas a nivel industrial. Para ello será necesario realizar un estudio de solubilidad de entre los LIs y DESs y con los compuestos fenólicos, así como el equilbrio entre fases de los sistemas ternarios por LI o DES + comp. fenólico + agua. Estos resultados nos permitirán seleccionar el solvente más adecuado, que permita eliminar de manera efectiva los fenoles del agua. Una vez selecionados, el siguiente paso será su aplicación a mezclas acuosas formadas por un mayor número de compuestos fenólicos, con el fin de acercarnos, en la medida de lo posible, al comportamiento real de una corriente residual generada en la industria química y que contenga este tipo de compuestos. Con todos estos datos experimentales se llevará a cabo la simulación del proceso empleando software comercial y se pondrá a punto el proceso de extracción en continuo a escala laboratorio. fenol,compuestos fenolicos, extraccion liquido-líquido, liquidos ionicos, solventes eutecticos de bajo punto de fusión (DES)O desenvolvemento da actividade industrial levado a cabo nas últimas décadas leva asociado, en moitos casos, un aumento considerable do volume de augas residuales que, dependendo da súa procedencia, poden conter gran cantidade de sustancias orgánicas e/ou inorgánicas en concentracións perjudiciales para o medioambiente (MA). Entre estas sustancias atópanse os fenoles, sustancias altamente contaminantes e presentes nun gran número de procesos industriais (industria papelera, agroalimentaria, farmacéutica, petroquímica...) A eliminación destes compostos das correntes de augas residuales antes do seu vertido é fundamental para a protección do MA. Neste sentido, a lexislación española sobre vertidos industriais limita o contido de fenoles no auga residual a un valor máximo de 1 mg/l. As tecnoloxías máis utilizadas para eliminar ou reducir o contido de fenoles en correntes acuosas son a biodegradación, a descomposición térmica e a absorción, pero ningunha delas parece ser eficaz cando a corrente de auga residual presenta altas concentracións de fenoles. A extracción líquida con disolventes ten como principal vantaxe que permite tratar correntes de augas residuales que conteñan unha elevada concentración de fenoles. Con todo, unha das principais limitacións é que os disolventes utilizados nos sistemas tradicionais de extracción líquido-líquido adoitan ser compostos orgánicos volátiles, os cales son tóxicos, inflamables e, en moitos casos, altamente contaminantes. Polo tanto, é importante explorar disolventes alternativos que sexan igualmente eficaces pero máis limpos e respetuosos co MA. Neste sentido, nos últimos anos, os líquidos iónicos (LI) e máis recientemente líquidos eutécticos de baixo punto de fusión (DES) acapararon a atención de gran parte da comunidade científica debido, especialmente, a que posúen unha combinación de propiedades únicas que os diferencian dos disolventes convencionais. En particular, a súa presión de vapor despreciable e as súas propiedades fisicoquímicas, como a polaridad, viscosidad e a afinidad por moitos compostos orgánicos e inorgánicos, convértenos en posibles candidatos para a súa utilización en sistemas multifásicos como axentes de separación. Nesta liña, o obxectivo principal deste proxecto consiste na aplicación de LI hidrofóbos e de DES como axentes de extracción na eliminación/redución do fenol e os seus compostos derivados (2-metilfenol, 2,4-dimetilfenol, 2-clorofenol, 4-nitrofenol,...) presentes nas correntes de augas residuales xeradas a nivel industrial. Para iso será necesario realizar un estudo de solubilidad de entre os Lis e DESs e cos compostos fenólicos, así como o equilbrio entre fases dos sistemas ternarios por LI ou DES comp. fenólico auga. Estes resultados permitirannos seleccionar o liquide máis adecuado, que permita eliminar de xeito efectivo os fenoles do auga. Unha vez selecionados, o seguinte paso será a súa aplicación a mesturas acuosas formadas por un maior número de compostos fenólicos, co fin de achegarnos, na medida do posible, ao comportamento real dunha corrente residual xerada na industria química e que conteña este tipo de compostos. Con todos estes datos experimentais levarase a cabo a simulación do proceso empregando software comercial e poñerase a punto o proceso de extracción en continuo a escala laboratorio. fenol,compostos fenolicos, extraccion liquido-líquido, liquidos ionicos, liquides eutecticos de baixo punto de fusión (DES)España. Comisión Interministerial de Ciencia y Tecnología. CTM2013-46093-PEspaña. Comisión Interministerial de Ciencia y Tecnología. BES-2014-06769

Recovery and elimination of phenolic pollutants from water using [NTf2] and [Nf2]-based ionic liquids

At present, pollution is one of the most important problems worldwide. Industrial growth makes it necessary to develop techniques to remove pollutant substances from water, since water is an important natural source for life. One of these techniques is liquid–liquid extraction, which is used to remove phenolic compounds from wastewaters. Volatile organic compounds are used as common extraction solvents in liquid–liquid extractions; nevertheless, some of their properties, such as toxicity and volatility, make it necessary to replace them with other less toxic solvents. In this work, the capability of four ionic liquids, based on bis(trifluoromethylsulfonyl)imide [NTf2] and bis(fluorosulfonyl)imide [Nf2] anions and different cations to remove phenolic compounds from water was studied. The phenolic compounds used in this study were phenol, o-cresol, and 2-chlorophenol, and the effects of the extraction solvent and phenol structures were analyzed. For that, a liquid–liquid extraction was carried out, and the extraction yield was determined. In general, high extraction efficiencies were obtained for all studied systems, obtaining the highest extraction efficiencies using the pyrrolidinium cation-based ionic liquids.Comisión Interministerial de Ciencia y Tecnología (España) | Ref. CTM2013-46093-

Hydrophobic deep eutectic solvents as extraction agents of nitrophenolic pollutants from aqueous systems

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGNitrophenolic compounds are hazardous substances, listed as priority pollutants by World Health Organization, due to their toxicity on both the environment and human health. They are used in agriculture as insecticides and fungicides substances, and they can contaminate water reserves by filtering through the soil into groundwater. Therefore, these substances must be removed from agricultural wastewater before being discharged. In this work, several Deep Eutectic Solvents, based on menthol, thymol and organic acid, are used as separation agents in liquid–liquid extraction to remove 2-nitrophenol and 4-nitrophenol from water. The optimal extraction conditions were studied and the better extraction yields were obtained using: (1:1) VDES:VW ratio and 30 min of stirring time. All extraction experiments were carried out at 298.15 K and 30 min of centrifugation time at 6000 rpm. As the results show, these deep eutectic solvents based on menthol can be used to extract both nitrophenolic compounds, while those based on thymol can only be applied for the removal of 4-nitrophenol. All studied solvents present high extraction efficiencies, over to 90%, assuring their capability as extraction agents in aqueous systems.Ministerio de Economía y Competitividad | Ref. CTM2013-46093-PXunta de Galicia | Ref. ED431B 2020/08Foundation for Science and Technology | Ref. UIDB/50020/202

Effect of temperature on physical properties for binary systems: deep eutectic solvent and alcohols

Compared with the conventional Ionic Liquids, Deep Eutectic Solvents (DES) are more biodegradable and biocompatible. Moreover, they are easily prepared with high purity at low cost. Because of this, an extensive study of both properties of pure DES and of their binary mixtures with alcohols, in function of temperature is very necessary and of considerable importance for the development and design of new processes using these solvents. Density, speed of sound, refractive index and viscosity of choline chloride and levulinic acid DES pure and their mixtures with alcohols have been studied at several temperatures and atmospheric pressure.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Densities and Derived Volumetric Properties of Ionic Liquids with [Nf(2)] and [NTf2] Anions at High Pressures

The densities of four ionic liquids: 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([E(3)Mim][Nf(2)]), n-propyl-n-methylpyrrolidinium bis(fluorosulfonyl)imide ([PMpyr][Nf(2)]), 1-butyl-l-methylpyrrolidinium bis(fluorosulfonyl)imide ([BMpyr][Nf(2)]), and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonil)imide ([BMpyr][NTf2]) were measured at temperatures (293.15 to 413.15) K and pressures (0.1 to 60) MPa. The experimental density data were modeled using the modified Tammann-Tait equation and the average absolute percentage deviations between measured and calculated values for all studied ionic liquids were less than 0.004%. The optimized parameters were used to calculate the isothermal compressibility, the isobaric thermal expansivity, the internal pressure, and the difference between specific heat capacities at constant pressure and at constant volume. The cation and anion influences on the properties of the ionic liquids were examined. The longer alkyl chains on cations are related to lower density of ionic liquids and ionic liquids with imidazole based cation are denser than those with pyrrolidinium cation. The presence of more stabile [NTf2](-) anion in ionic liquids leads to greater densities comparing to [Nf(2)](-) anion

High pressure densities and derived thermodynamic properties of deep eutectic solvents with menthol and saturated fatty acids

Densities of four Deep Eutectic Solvents (DESs) based on menthol and organic acids (menthol:octanoic acid (1:1), menthol:decanoic acid (1:1), menthol:dodecanoic acid (2:1) and decanoic acid:octanoic acid (1:3)) were measured at high pressures (0.1 to 60) MPa and several temperatures (293.15 to 413.15) K. Tammann-Tait equation was used to model the experimental density data; the average absolute percentage deviations between calculated and experimental data were less or equal 0.012 %. The influence of the temperature and pressure on the derived volumetric properties: isothermal compressibility (k(T)), isobaric thermal expansivity (alpha(p)), internal pressure (p(int)) and difference between heat capacity at constant pressure (c(p)) and constant volume (c(v)) was analysed. Considering the experimental results, it is possible to observe that deep eutectic solvent formed by linear organic acids presents higher density values than those formed by menthol, being the densest the solvent formed by dodecanoic and octanoic acid. Attending to the derived volumetric properties in general, isothermal compressibility and isobaric thermal expansivity increase as temperature increases and decrease with pressure for all studied systems, being the octanoic acid based DESs slightly more compressible than the other studied DESs

High pressure densities and derived thermodynamic properties of deep eutectic solvents with menthol and saturated fatty acids

Densities of four Deep Eutectic Solvents (DESs) based on menthol and organic acids (menthol:octanoic acid (1:1), menthol:decanoic acid (1:1), menthol:dodecanoic acid (2:1) and decanoic acid:octanoic acid (1:3)) were measured at high pressures (0.1 to 60) MPa and several temperatures (293.15 to 413.15) K. Tammann-Tait equation was used to model the experimental density data; the average absolute percentage deviations between calculated and experimental data were less or equal 0.012 %. The influence of the temperature and pressure on the derived volumetric properties: isothermal compressibility (kT), isobaric thermal expansivity (αp), internal pressure (pint) and difference between heat capacity at constant pressure (cp) and constant volume (cv) was analysed. Considering the experimental results, it is possible to observe that deep eutectic solvent formed by linear organic acids presents higher density values than those formed by menthol, being the densest the solvent formed by dodecanoic and octanoic acid. Attending to the derived volumetric properties in general, isothermal compressibility and isobaric thermal expansivity increase as temperature increases and decrease with pressure for all studied systems, being the octanoic acid based DESs slightly more compressible than the other studied DESs.Ministerio de Economía y Competitividad | Ref. CTM2013- 46093-PMinisterio de Economía y Competitividad | Ref. BES-2014-067694Ministerio de Economía, Industria y Competitividad | Ref. CTQ2016-77422-C2-1-