Thermodynamic Study of Aggregation of Cholinium Perfluoroalkanoate Ionic Liquids

To advance the ionic liquid (IL) platform to tailor fluorinated surfactant properties, the aim of this work is to evaluate the surfactant properties of cholinium-based salts bearing perfluoroalkanoate anions. Novel surfactant ILs containing the cholinium cation [Ch]⁺ combined with different perfluoroalkanoate anions, namely perfluoropentanoate [PFPent]⁻, perfluorohexanoate [PFHex]⁻, perfluoroheptanoate [PFHept]⁻, and perfluorooctanoate [PFOct]⁻, were synthesized. The critical micelle concentrations (CMCs) were determined using an ionic conductivity method, at different temperatures. Thermodynamic parameters of micellization were also evaluated. The results indicate that the CMC value decreases in a linear manner with the increment of the fluoroalkyl chain length in the anion. The evaluation of the thermodynamic parameters shows that the micellization is spontaneous and entropically driven and that the enthalpy of micellization is very small. It was also observed that the introduction of the cholinium cation in these surfactants allows for smaller CMC values when compared to that of other tetraalkylammonium-based surfactants with the same fluorinated anions, in short to more efficient and green surfactants. This result is probably due to counterion association and not to counterion binding to micelle surface

Fatty Acids-Based Eutectic Solvents Liquid Membranes for Removal of Sodium Diclofenac from Water

Nowadays, the scarcity of clean fresh water is a major concern to public health. One of the main issues linked with this topic is the unavoidable contamination of water bodies with active pharmaceutical ingredients, which results from production and metabolization of prescribed and over the counter drugs closely related to human health and wellbeing. As the currently available techniques for removal of micropollutants (MPs) from wastewater are not sufficiently broad, efficient, and cost effective, new sustainable alternatives are required to prevent the contamination of water bodies which can compromise the viability of aquatic ecosystems and, ultimately, life on earth as we know it. Herein, a natural eutectic solvent (ES), based on fatty acids, is proposed to remove important MPs, sodium diclofenac, the most used nonsteroid anti-inflammatory drug, and a plasticizer, Bisphenol A (BPA), through liquid–liquid extraction (LLE), as well as preparation of liquid membranes. The extraction of sodium diclofenac through LLE reached an efficiency of (97 ± 1)% that was maintained when shifting to the liquid membranes while reducing the quantity of solvent to only 1.5% of that required in LLE. These membranes were reused through 10 cycles of extraction without major loss of efficiency. The optimal extraction efficiency of BPA using ES supported in membranes reached (63 ± 1)%. The easy preparation of hydrophobic natural eutectic solvents-based absorbent materials through their impregnation in porous inert supports enables the development of highly efficient and cost-effective adsorption technology for the removal MPs from water

Understanding the Role of Cholinium Carboxylate Ionic Liquids in PEG-Based Aqueous Biphasic Systems

This work aims at exploring new sustainable separation processes based on ionic liquids. Aqueous biphasic systems (ABS) based on poly­(ethylene glycol) (PEG) with low molecular weight (600 and 4000 g mol^–1) and cholinium-based ionic liquids and salts containing anions derived from carboxylic acids (oxalate, malonate, succinate, l-malate, fumarate, glutarate and citrate), available in natural compounds, are here presented. Contrary to common ionic liquids, the cholinium-based ionic liquids used in this work are biodegradable, nontoxic, cheap, and simple to prepare, and PEG is also a cheap and nontoxic phase promoter agent. The data reported in this work allows novel insights into the phase splitting mechanism of these ABSs regarding the influence of alkyl chain length of the anion and the presence of substituent groups in the anion. The effect of PEG molecular weight in the ABS was also addressed. Furthermore, the possible application of these systems for the extraction/separation of antioxidants, namely, <i>tert</i>-butylhydroquinone (TBHQ), was evaluated

Menthol-based Eutectic Mixtures: Hydrophobic Low Viscosity Solvents

Inspired by one of the major problems in the pharmaceutical industry, we advantageously used the formation of eutectic mixtures to synthesize new solvents. The aim of this work is to identify low viscosity, cheap, biodegradable and hydrophobic eutectic solvents from natural resources. Consequently, novel eutectic mixtures based on dl-menthol and naturally occurring acids, namely pyruvic acid, acetic acid, l-lactic acid, and lauric acid, were synthesized and are here reported for the first time. The obtained dl-menthol-based eutectic mixtures were analyzed using NMR and FTIR spectroscopy in order to check their structures and purities and to confirm the interaction of the two compounds leading to the eutectic formation. Important solvent thermophysical properties, such as density and viscosity, of the prepared eutectic solvents with different water contents (dried and water-saturated) were measured. Finally, taking advantage of their hydrophobic character, namely the formation of two phases with water at room temperature, four different biomolecules, caffeine, tryptophan, isophthalic acid, and vanillin, were extracted and the extraction efficiencies of the prepared eutectic solvents compared

New Low-Toxicity Cholinium-Based Ionic Liquids with Perfluoroalkanoate Anions for Aqueous Biphasic System Implementation

This work explores the widening of properties of cholinium-based ionic liquids (ILs) through their combination with perfluoroalkanoate anions so that higher number of aqueous biphasic systems (ABSs) containing nontoxic cholinium-based ILs is available. For that purpose, six cholinium perfluoroalkanoate ILs were synthesized and their cytotoxicity was evaluated using three different animal cell lines, envisaging biotechnology applications. Ternary phase equilibrium data for ABSs composed of the cholinium perfluoroalkanoate, with fluoroalkyl chains from C₂ up to C₇, using a strong salting out agent, K₃PO₄, were determined at 25 °C. The results show the relevant role of the size of fluorinated alkyl chain length in the anion since, contrary to other ABSs containing ILs with increasing alkyl chain length in the anion, the ABSs with cholinium perfluoroalkanoates present well-spaced solubility curves, allowing the conclusion that these ABSs can be tuned by a proper choice of the IL. The phase splitting mechanism was also disclosed through water activity measurements