Application of calorimetry and thermal analysis to determine the liquid range and the environmental toxicity of ionic liquids

This PhD Thesis is focused on the applicability of thermal analysis and calorimetry techniques to determine phase transitions (through Differential Scanning Calorimetry (DSC)), thermal stability (measured by Thermogravimetric Analysis (TGA)) and ecotoxicity (trhough Thermal Activity Monitor (TAM) and seed germination response tests) of ionic liquids (ILs) to be used as lubricants and/or absorbents in heat pumps. The studied compounds are based on different anions (imide, triflate, sulphonate, phosphate) and cations (phosphonium, pyridinium, pyrrolidinium, imidazolium, choline) in order to determine possible dependences of these properties according to a selected ion. From the results of DSC and TGA techniques, the liquid range of the selected ILs was estimated using as limits of this interval tm and tonset/t´0.10/10h

Temperature liquid range of two choline based ionic liquids

The 20th International Electronic Conference on Synthetic Organic Chemistry session Ionic LiquidsLiquid temperature range of two ionic liquids (ILs) with the common cation, Choline, is determined in this work. The selected ILs are Choline tosylate [Chol][Tos] and Choline dicyanamide [Chol] [DCN]. The lower limit of liquid range is given by solid-liquid transitions and it is determined using differential scanning calorimetry (DSC). Upper limit is given by degradation temperature which is determined using the thermogravimetric technique (TGA). Dynamic and isothermal methods have been combined to estimate the maximum operation temperature. Additionally, a deeper study of the effect of the heating and cooling rate on the temperature and shape of the transitions observed in DSC curves of [Chol] [DCN] was performed. A common trend has been observed for melting and degradation temperatures of selected liquids: [Chol][DCN]< [Chol][Tos]This study was financed by the project EM2013/031 (Xunta de Galicia, Spain) and the network REGALIS R2014/015 (Xunta de Galicia, Spain

Influence of Small Quantities of Water on the Physical Properties of Alkylammonium Nitrate Ionic Liquids

This paper presents a comprehensive study of two alkylammonium nitrate ionic liquids. As part of this family of materials, mainly ethylammonium nitrate (EAN) and also propylammonium nitrate (PAN) have attracted a great deal of attention during the last decades due to their potential applications in many fields. Although there have been numerous publications focused on the measurement of their physical properties, a great dispersion can be observed in the results obtained for the same magnitude. One of the critical points to be taken into account in their physical characterization is their water content. Thus, the main objective of this work was to determine the degree of influence of the presence of small quantities of water in EAN and PAN on the measurement of density, viscosity, electrical conductivity, refractive index and surface tension. For this purpose, the first three properties were determined in samples of EAN and PAN with water contents below 30,000 ppm in a wide range of temperatures, between 5 and 95 °C, while the last two were obtained at 25 °C. As a result of this study, it has been concluded that the presence of water is critical in those physical properties that involve mass or charge transport processes, resulting in the finding that the absolute value of the average percentage change in both viscosity and electrical conductivity is above 40%. Meanwhile, refractive index (≤0.3%), density (≤0.5%) and surface tension (≤2%) present much less significant changesThis research was funded by the Spanish MINISTRY OF ECONOMY AND COMPETITIVENESS, grant numbers MAT2017-89239-C2-1-P and MAT2017-89239-C2-2-P. D. Ausín thanks the funding support of Fundación Segundo Gil Dávila. J.J. Parajó thanks the funding support of I2C postdoctoral program of Xunta de GaliciaS

Effects of ethylimidazolium nitrate and the aluminium nitrate salt mixtures on germination of three forest species

This article belongs to the Proceedings of The 23rd International Electronic Conference on Synthetic Organic ChemistryIonic liquids are synthetic compounds with melting temperatures lower than 100 °C and with high ability of modification of their physical and chemical properties from changes in their chemical structure. Although the number of applications in the last years has been continuously increasing, their effects on the different terrestrial ecosystems have been scarcely studied. In this work, the effects of the ionic liquid ethylammonium nitrate (EAN), the aluminum nitrate salt (Al(NO3)3), and the saturated mixture of both components on the germination of three forest species were studied. Different doses, from 0% to 10% weight, of the three treatments were applied at seeds of three different forest species (Eucalyptus globulus Labill, Pinus radiata D. Don, and Pinus sylvestris L.) and the germination of these seeds was continuously monitored for 35 days. The results showed that the addition of ionic liquid, salt, and mixture provoke the reduction of germination for all the species. Concentrations of 5% and higher incite the total inhibition of the germination of all species for all the treatments, with the EAN treatment being the most harmfulThis work was supported by Xunta de Galicia through GRC ED431C 2016/001 and IN607A 2017/6 projects, the Spanish Ministry of Science, Innovation and Universities and the European Regional Development Fund (ERDF) in the framework of the FIRESEVES (AGL2017-86075-C2-2-R) project and the Competitive Reference BIOAPLIC (ED431C2019/07), the Strategic Researcher Cluster BioReDeS (ED431E 2018/09), and the Galician Network of Ionic Liquids (ReGaLIs) ED431D 2017/06. J. J. Parajó gives thanks for funding support from the I2C Postdoctoral Program of Xunta de GaliciaS

Ecological effects of ionic liquids on microbial activity of a soil and on tree seed germination

The 19th International Electronic Conference on Synthetic Organic Chemistry session Ionic LiquidsIonic liquids (ILs) are considered one of the most promising green alternatives to molecular organic solvents. Nevertheless, before a widespread use of these compounds in a determined application, the knowledge of their ecotoxicity and biodegradability must be defined. In this work the effect of addition of different doses of 1-butil-2,3-dimethylimidazolium trifluoromethanesulfonate, [C4C1C1Im][OTf], on microbial activity of a soil under Pinus pinaster Aiton and on the seed germination of species of P. pinaster , Pinus sylvestris L., Pinus radiata D. Don and Eucalyptus globulus Labill were analyzed. Additionally, seed germination test were also applied to this IL after being subjected to heat treatment. A microcalorimeter Thermal Activity Monitor (TAM-III) TA-Instruments was used to determine the influence of the addition of four doses (10 %, 25 %, 50 % and 75 %) on the microbial activity of a Galician soil, under P. pinaster. Methodology was widely exposed in previous works [1]. From the data obtained in these experiments, the calculation of microbial growth was performed [2]. Seed germination test of selected species were carried out for several doses of ILs (10 %, 1 %, 0.1 % and 0.01 %). The degradation treatment of the IL was carried out during 24 h in an oven at the temperature of 200 °C. Five replies with 25 seeds per Petri dish were incubated in a Phytotron (Climas AGP890) for every species and treatments. Seeds were maintained for 16 h under light at 24 °C and in the dark for 8 h at 16 °C during 45 days, when the germination was completed in all the species [3, 4]. Results of soil microbial activity and germination obtained for this IL were compared with the corresponding to other ILs, previously studied in our laboratory. Dose of 10 % inhibited totally the germination of the four species and dose of 1 % provoked an important reduction with regard to the control, both, for degraded and no-degraded IL. Nevertheless, in spite of all the doses showed differences on calorimetric parameters with regard to control; only the dose of 75 % does not show soil microbial response

Effect of the Addition of [C3C1im][NTf2] in Pine Seed Germination and in Soil Microbial Activity

The 18th International Electronic Conference on Synthetic Organic Chemistry session Ionic LiquidsDespite the increasing number of papers about the study of the properties of the ionic liquids (ILs), the knowledge of their ecotoxicity and biodegradability are not still well established. In this work the effect of the addition of five different concentrations of aqueous solutions (10%, 1%, 0.1%, 0.01% and 0% (control) in weight) of the IL [C3C1im][NTf2] on the seed germination of six species of pine and on the microbial activity of a soil under P. radiata was determined. This IL was selected taking into account that his thermophysical properties make it a good candidate to being used as lubricant. Seed germination test of species of Eucalyptus globulus, Pinus halepensis, Pinus nigra, Pinus pinaster, Pinus sylvestris and Pinus radiata were carried out. The reason to select these species was their wide geographical distribution and their great economic, social and ecological interest. Five replies with 25 seeds per Petri dish were incubated for every species and treatments, in total 3750 seeds were incubated (6 species x 5 treatments x 5 replicates x .25 seeds) Germinated seeds were monitoring every Monday, Wednesday and Friday. Germination had been completed in all the species 45 days of incubation. On the other hand, calorimetric experiments were performed using a microcalorimeter 2277 Thermal Activity Monitor (TAM) Thermometric AB. Measurements were carried out in hermetically sealed 5 ml stainless steel ampoules. Soil samples of 1 g size at water-holding capacity were treated with 0.2 ml of aqueous glucose solution to activate the microbial metabolism.Additionally, a comparison between the effects of this IL in the seed germination and soil microbial activity and the corresponding to two well-known salts, sodium chloride and potassium nitrate, in the same conditions was stablishedThis study was financed by the project EM2013/031 (Xunta de Galicia, Spain

Thermal characterization of ethylammonium nitrate

The 20th International Electronic Conference on Synthetic Organic Chemistry session Ionic LiquidsBeyond their traditional usage in fuel cell applications, the category of protic ionic liquids (PILs) has been recently signalled as a potential candidate for battery applications. Despite being the oldest known IL, and of having been extensively characterized in most of its properties, a full thermal and stability analysis of ethylammonium nitrate (EAN) both in its solid and liquid phases is still lacking. In the present work thermal analysis techniques were used to characterize its thermal transitions and thermal stability. A differential scanning calorimeter DSC Q100 TA-Instruments with aluminium pans hermetically sealed was used to determine the different state transitions experienced by the IL during heating and cooling cycles. Results showed that this IL is a very good crystal-former with melting and freezing peaks at 17ºC and -28ºC respectively. Moreover, stability analysis has been performed by means of a thermogravimetric analyser (TGA 7-Perkin Elmer) operating in dynamic and isothermal modes, under nitrogen and dry air atmospheres was used to perform thermal stability analysis. Similar onset temperatures in air and nitrogen of 248±4ºC were obtained. Additionally, activation energy of the degradation process of this IL has been determined using the Arrhenius equationThis work was funded by the Xunta de Galicia (Spain) through grants EM2013/031 and AGRUP2015/11 and by the network REGALIS R2014/015. The financial support of the Spanish Ministry of Economy and Competitiveness through grants MAT2014-57943-C3-1-P, MAT2014-57943-C3-2-P and MAT2014- 57943-C3-3-P is also gratefully acknowledged. Funding from the European Union (COST Action CM 1206) is also acknowledge

Thermophysical properties of n‑alkyl‑ammonium nitrate ionic liquids (n=2,3,4) pure and water saturated for energy applications

Phase transition temperatures of three ionic liquids (ILs) with ammonium cations of different alkyl chain length and nitrate common anion were determined in this paper by differential scanning calorimetry. Thermal stability of these ILs in air and nitrogen atmosphere and the maximum operation temperatures of the compounds were also studied using a thermogravimetric analyser. Furthermore, thermophysical properties as density, viscosity, thermal conductivity, and heat capacity against temperature of these pure ionic liquids were determined and compared with the corresponding values for water saturated samples. For this purpose, different techniques were employed: for density and viscosity a rotational automated viscodensimeter; for thermal conductivity measurements a thermal conductimeter that follows the transient hot-wire method; and for heat capacity measurements a microdifferential scanning calorimeter. Different behaviours were observed depending on the analysed thermophysical properties. In case of dried samples, density and thermal conductivity decrease with alkyl chain; for saturated samples, same tendency is observed for density but is the opposite in case of thermal conductivity. Isobaric specific heat and viscosity increase with alkyl chain length in case of dried samples; for saturated samples same tendency is observed for the viscosity, whereas the tendency is the contrary in case of isobaric specific heatAuthors acknowledge M. Gómez (RIAIDT-USC) for the technical support in DSC and TGA measurements. This work was supported by Spanish Ministry of Economy and Competitiveness and FEDER Program through the projects MAT2017-89239-C2-1-P, PID2020-112846RB-C22 as well as by Xunta de Galicia through GRC ED431C 2020/10 project and the Galician Network of Ionic Liquids (ReGaLIs) ED431D 2017/06. P. Vallet thanks funding support of FPI Program from Spanish Ministry of Science and J. J. Parajó and M. J. G. Guimarey thank the I2C postdoctoral Program of the Xunta de Galicia, for their support in funding the study. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer NatureS

On the physical properties of mixtures of nitrate salts and protic ionic liquids

We report a systematic study of the effect of salt concentration and its cation valence on several equilibrium and transport properties of mixtures of the model protic ionic liquid ethylammonium nitrate with monovalent (LiNO3), divalent (Mg(NO3)2 and Ca(NO3)2), and trivalent (Al(NO3)3) salts. These properties, determined by appropriate experimental techniques, include density, sound velocity, refractive index, surface tension, conductivity and viscosity. Single-particle dynamics and radial distribution functions were also analyzed by means of molecular dynamics simulations. The temperature dependence of the conductivity was studied in the Vogel-Fulcher-Tammann framework, and we obtained effective activation energies, fragility indexes, and Vogel temperatures. In addition, we performed a high-temperature Arrhenius analysis and we calculated the activation energies of both conductivity and viscosity. Finally, the exponents of the fractional Walden rule for the different mixtures were obtained and the ionicities and fragilities of the systems were analyzed, proving that all the mixtures are subionic and fragile. The distortion of the network of hydrogen bonds characteristic of protic ionic liquids and the formation of long-lived anionic aggregates composed of the cations of the added salt and the nitrate anions in their first solvation shell were found to have a deep impact on the analyzed properties. The role of the surface charge density of the salt cations on the structure and transport properties of the solutions is detailedly analyzed and related to solvation of salt species in the polar nanoregions of the ionic liquid (nanostructured solvation)The financial support of the Spanish Ministry of Economy and Competitiveness (Projects MAT2017-89239-C2-1-P and MAT2017-89239- C2-2-P) is gratefully acknowledged. Moreover, this work was funded by the Xunta de Galicia (ED431D 2017/06, ED431E 2018/08, GRC ED431C 2016/001 and GRC ED431C 2020/10). All these research projects were partially supported by FEDER. P. V. thanks the Spanish Ministry of Science, Innovation and Universities for his FPI grant (PRE2018-084212). T.M.-M. thanks the Spanish Ministry of Science, Innovation and Universities for her Juan de la Cierva grant (IJC2018-036774-I).J. J. Parajó thanks the funding support of I2C postdoctoral program of Xunta de Galicia. Y. A. thanks the funding support from postdoctoral Program of Xunta de Galicia (ED481B-2021-027)S

Ecotoxicity of binary mixtures of ILs and inorganic salts of electrochemical interest

The applicability of ionic liquids (ILs) has increased over the last years, and even new opportunities are becoming a reality, i.e. mixtures of pure IL and inorganic salt as electrolytes for smart electrochemical devices, yet the effects on the environment are almost unknown. In this work, the ecotoxicity of two pure protic ILs (Ethylammonium nitrate and Ethylimidazolium nitrate) and two pure aprotic ILs (butylmethylpyrrolidinium bis(trifluoromethylsulfonyl)imide and butyldimethylimidazolium bis(trifluoromethylsulfonyl)imide) and that of their binary mixtures with inorganic salts with common cation was tested towards changes in the bioluminescence of the bacteria Aliivibrio fischeri, using the Microtox® standard toxicity test. EC50 of these mixtures was determined over three standard periods of time and compared with the corresponding values to pure ILs. Results indicate that the aprotic ILs are more toxic than protic and that aromatic are more toxic than non-aromatic. The addition of inorganic mono (LiNO3), di (Ca(NO3)2·4H2O, Mg(NO3)2·6H2O) and trivalent (Al(NO3)3·9H2O) salts in binary mixtures with EAN was analysed first. The latter was found to induce an important increase in toxicity. Finally, mixtures of IL-inorganic lithium salt (LiNO3, for the protic ILs and LiTFSI for the aprotic ILs) toxicity was also studied, which showed toxicity levels strongly dependent on the IL of the mixtureOpen Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by the Spanish Ministry of Economy and Competitiveness and FEDER Program through the MAT2017-89239-C2-1-P project as well as by the Xunta de Galicia through the GRC ED431C 2020/10 project and the Galician Network of Ionic Liquids (ReGaLIs) ED431D 2017/06. P. Vallet and J. J. Parajó wish to thank the FPI program from the Spanish Ministry of Science, Education and Universities and the I2C postdoctoral program of the Xunta de Galicia for their support in funding the studyS