A simple approach for the determination and characterization of ternary phase diagrams of aqueous two-phase systems composed of water, poly(ethylene) glycol and sodium carbonate

In this work, an experimental protocol to determine liquid-liquid phase diagrams of aqueous two-phase systems (ATPS) in a chemical engineering course is described. Throughout this laboratory set of experiments, students will determine liquid-liquid ternary phase diagrams, comprising the solubility curves, tie-lines, tie-line lengths and critical points, for systems composed of poly(ethylene) glycol, sodium carbonate and water. Furthermore, students will apply the NRTL (Non-Random Two Liquid) model to fit the experimental tie-lines.publishe

Enhancing artemisinin solubility in aqueous solutions: searching for hydrotropes based on ionic liquids

Artemisinin is a sesquiterpenoid lactone peroxide, known for its potent antimalarial activity that can be extracted from Artemisia annua L. This compound is only sparingly soluble in water, making its extraction using environmental-friendly and non-toxic aqueous solvents difficult. In the attempt to overcome this limitation, hydrotropes, which are a class of compounds that can assist in increasing the solubility of hydrophobic solutes in water, were investigated in this work. In particular, the hydrotropic capability of ionic liquids (ILs) on the aqueous solubility of artemisinin was studied. The effects of IL concentration and anion nature of 1-butyl-3-methylimidazolium-based ILs on the solubility of artemisinin at 303.2 K in water were evaluated. It is here shown the excellent capacity of ILs containing thiocyanate or dicyanamide anions to enhance the solubility of artemisinin in aqueous media, with a magnitude comparable to that obtained with the best organic solvents. Furthermore, solvatochromic parameters of the ILs aqueous solutions were also measured and combined with COSMO-RS and the cooperative hydrotropy model to establish relations between the artemisinin solubility enhancement and the solvent characteristics. The solubility enhancement of artemisinin is favored by the apolarity of the medium and the lower hydrogen-bond acceptor character of the hydrotrope.This work was developed within the scope of the projects CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, CIMO-Mountain Research Center, UIDB/00690/2020, all financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. Isabela Sales and Silvana Mattedi thanks the finantial support from CAPES and CNPq/Brazil (CAPES: Proc. 88881.189075/2018-01 and 88887.494428/2020-00. CNPq: Grant 303089/2019-9 and Proc.438036/2018-2).info:eu-repo/semantics/publishedVersio

Modeling of the binodal curve of ionic liquid/salt aqueous systems

Ionic Liquid-based Aqueous Two Phase Systems (ILATPS) are an innovative technique to separate biomolecules that combines the advantages of liquid–liquid extraction and hydrophilic ionic liquids. Most ILATPS are based on ionic liquids and conventional inorganic salts, and the phase envelope, described by the binodal curve, is usually modeled by empirical equations that are used to determine the phase compositions and assess the ionic liquid recyclability. However, these empirical equations may provide a poor extrapolation ability or low accuracy at the extreme regions of the binodal curve or suffer from problems of convergence. Therefore, the aim of this work is the analysis of the binodal curve equations, comparing the models reported in the literature to describe ILATPS and proposing alternative equations to improve accuracy or to reduce the mathematical complexity. For this purpose, a database compiling binodal experimental data of 100 ILATPS has been built, so that the analysis could make it possible to obtain representative conclusions for all these systems. Several models were developed, and different statistical criteria were used to assess the advantages and disadvantages of each one of these models for the binodal curve. The results show that, when accuracy is critical, a proposed model with just an additional parameter reduced more than 25% the residual mean squared error (RMSE) with respect to the commonly used equation, without losing the statistical significance of the parameters. For complex problems where an explicit equation in both the concentration of ionic liquid and of salt is needed, the use of an explicit model developed with 3 adjusted parameters that kept high accuracy (R2 > 0.996 and RMSE < 0.66) is proposed. Finally, the analysis also revealed that a fitting method based on the minimization of relative errors is recommended to increase the accuracy of the binodal curve at high salt concentrations, which is the crucial region for assessing the recyclability of the ionic liquid.This work was developed in the scope of the project CICECO Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and co-financed by FEDER under the PT2020 Partnership Agreement. The authors also acknowledge FCT for the Post-doctoral grant SFRH/BPD/79263/2011 of S.P.M. Ventura

Ionic liquid-mediated recovery of carotenoids from the bactris gasipaes fruit waste and their application in food-packaging chitosan films

In this work, a process for the extraction and purification of carotenoids from the fruit Bactris gasipaes was developed. Ethanolic and aqueous solutions of ionic liquids (ILs) and surfactants were evaluated on the extraction of these pigments. Thus, we developed an optimized sustainable downstream process mediated by the best solvent with further isolation of the carotenoids and the recyclability of the IL used. The process was characterized not only in terms of efficiency but also regarding its environmental impact. The recyclability of the solvents as well as the high efficiency (maximum yield of extraction of carotenoids = 88.7 ± 0.9 μgcarotenoids·gdried biomass–1) and the low environmental impact of the integrated process developed in this work were demonstrated. In the end, in order to incorporate functional activity for an alternative food-packaging material, carotenoids were successfully applied on the preparation of chitosan-based films with excellent results regarding their mechanical parameters and antioxidant activity.publishe

The antagonist and synergist potential of cholinium-based deep eutectic solvents

The design of environmentally friendlier solvents has gained increasing relevance in the last decade. Deep eutectic solvents (DES) have recently emerged, with advantages like low-cost and putative lower environmental impact. However, information about DES toxicity is still scarce. This work aims to contribute to profiling the ecotoxicity of DES based on cholinium chloride ([Chol]Cl). Six DES were addressed, combining [Chol]Cl (as hydrogen bond acceptor - HBA) with ethylene glycol, glycerol, 1,2-propanediol, propionic acid, 1-propanol, and urea as hydrogen bond donors (HBD), in different molar ratios. The Microtox® Acute Toxicity Test, was used for assessing their toxicity towards the marine bacteria Allivibrio fischeri . Because the dissociation of DES in water is expected, analysis appraising the mixtures toxicity theory should be considered, which is a step forward in this field. This analysis suggested that [Chol]Cl and all HBD with the exception of propionic acid:[Chol]Cl 1:2 and 4:1 behave antagonistically, which is contrary to what has been suggested previously. The most extreme cases are Urea:[Chol]Cl and 1-Propanol:[Chol]Cl, with EC50 values higher than their starting materials dosed singly, configuring very promising and biocompatible alternative solvents. Toxicity was found to be dependent on DES composition, as well as on molar proportions of the starting materials.publishe

Emerging seaweed extraction techniques using ionic liquids

In the last few decades, interest in primary and secondary metabolites from seaweeds has increased due to their high potential in important fields such as pharmaceuticals and cosmetics. In this context, the development of processes of extraction and purification that overcome the principal disadvantages of conventional methodologies is of utmost importance. Ionic liquids (ILs) have emerged as an alternative class of solvents in the extraction of compounds from a biomass. In this chapter, literature addressing the use of ILs in studies of extraction, purification, and biomass dissolution regarding seaweeds will be analyzed and discussed.publishe

Multiproduct Microalgae Biorefineries Mediated by Ionic Liquids

Ionic liquids (ILs) are salts with low melting points that can be used as solvents for mild extraction and selective fractionation of biomolecules (e.g., proteins, carbohydrates, lipids, and pigments), enabling the valorisation of microalgal biomass in a multiproduct biorefinery concept, while maintaining the biomolecules’ structural integrity and activity. Aqueous biphasic systems and emulsions stabilised by core-shell particles have been used to fractionate disrupted microalgal biomass into hydrophobic (lipids and pigments) and hydrophilic (proteins and carbohydrates) components. From nondisrupted biomass, the hydrophobic components can be directly extracted using ILs from intact cells, while the most fragile hydrophilic components can be obtained upon further mechanical cell disruption. These multiproduct biorefinery concepts will be discussed in an outlook on future separations using IL-based systems.</p

Extraction of chlorophyll from wild and farmed Ulva spp. using aqueous solutions of ionic liquids

•Process to extract chlorophylls from Ulva sp.•Biomasses from two European locations were studied.•A tensioactive ionic liquid was selected as the best solvent.•The chlorophylls extracted are chemically stable. Products extracted from natural resources are an increasing trend in several fields promoted by consumer demand. Allied to the importance attached to the concept of “natural product” should be the way the “natural product” is obtained. In this work, chlorophyll was extracted from batches of wild-harvested and farm-raised green macroalgae Ulva spp. from two different European locations, Portugal and France. The performance of different aqueous solutions of tensioactive compounds such as ionic liquids and common surfactants in the yield of extraction of chlorophyll was studied and the operational conditions of extraction were optimized. The effect of drying the biomass on the yield of extraction of chlorophyll was evaluated as well as the effect of both locations (and the specific conditions of each location in terms of nutrients, water temperature and light intensity) in chlorophyll production. After optimization of all operational conditions, a maximum yield of extraction of 5.96 mgchl·gdry algae−1 was obtained using 250 mM of tributyltetradecylphosphonium chloride ([P4,4,4,14]Cl). The use of this solvent has allowed the development of a cost-effective (conclusion obtained after the economic analysis) and efficient process capable of maintaining the stability of the final product for more than one month

Evaluation of COSMO-RS for the prediction of LLE and VLE of water and ionic liquids binary systems

Ionic liquids (ILs) have achieved special and dedicated attention from the scientific community in recent years and a large number of studies involving different features of properties and applications of ILs have been presented. The complete understanding of the phase behaviour of ILs with water is an important issue yet there are few experimental data on their phase equilibria. In this work the predictive capability of COSMO-RS, a predictive model based on unimolecular quantum chemistry calculations, was evaluated for the description of the liquid–liquid equilibria (LLE) and the vapour–liquid equilibria (VLE) of diverse binary mixtures of water and ILs. The effect of the ions conformers on the quality of the predictions was assessed and the quantum chemical COSMO calculation at the BP/TZVP level derived from the lowest energy conformations was adopted. While the LLE predictions degrade with increasing the hydrophilic IL anion character, in general a good qualitative agreement between the model predictions and experimental VLE and LLE data was obtained. COSMO-RS showed to be very helpful as an a priori predictive method in order to find suitable candidates for a certain task or specific applications before extensive experimental measurements.publishe

Chiral ionic liquids in the development of enantioselective aqueous biphasic systems

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