Lanthanide-Based Organic Salts: Synthesis, Characterization, and Cytotoxicity Studies.

The formulation of magnetic ionic liquids (MILs) or organic salts based on lanthanides as anions has been explored. In this work, a set of choline-family-based salts, and two other, different cation families, were combined with Gadolinium(III) and Terbium(III) anions. Synthetic methodologies were previously optimized, and all organic salts were obtained as solids with melting temperatures higher than 100 °C. The magnetic moments obtained for the Gd(III) salts were, as expected, smaller than those obtained for the Tb(III)-based compounds. The values for Gd(III) and Tb(III) magnetic salts are in the range of 6.55-7.30 MB and 8.22-9.34 MB, respectively. It is important to note a correlation between the magnetic moments obtained for lanthanides, and the structural features of the cation. The cytotoxicity of lanthanide-based salts was also evaluated using 3T3, 293T, Caco2, and HepG2 cells, and it was revealed that most of the prepared compounds are not toxic.

Remediation of soils contaminated with total petroleum hydrocarbons through soil washing with surfactant solutions.

Soil fulfils vital functions for life on Earth and so, just like water and air, its protection from all sources of contamination is a major concern. However, the extensive use of petroleum derived products, either as energy sources or as commodities, leads to important environmental liabilities. Ex situ soil washing is a technology to concentrate contaminants, allowing soil cleaning and the reuse of extracted petroleum derived products. This work focuses on the optimization of ex situ soil washing process using surfactants, introducing an evaluation of the washing solution recycling and its after use safe disposal, promoting the reduction of raw materials, energy and water resources costs. Two surfactants, sodium dodecyl sulphate (SDS) and polyoxyethylene sorbitan monooleate (Tween 80), were tested in the decontamination of an artificially contaminated soil with engine lubricant oil waste. The optimization of the washing conditions, such as stirring speed, liquid-solid ratio, number of washing stages, and surfactant concentration, was carried out using a design of experiments (DOE) software, so that the maximum extraction efficiency of total petroleum hydrocarbons (TPHs) was achieved. A TPH removal efficiency of (80.7 ± 3.2)% was obtained with Tween 80 after 5 h of washing and (90.7 ± 2.8)% with SDS after 2 h at 200 rpm on an orbital shaker with a liquid to solid ratio (L/S) of 15. The potential for reuse of the washing solutions was evaluated. Finally, the discharge of the washing solution was considered using activated carbon to remove the surfactants and ensure its safe disposal.

Tunning CO2 Separation Performance of Ionic Liquids through Asymmetric Anions.

This work aims to explore the gas permeation performance of two newly-designed ionic liquids, [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2], in supported ionic liquid membranes (SILM) configuration, as another effort to provide an overall insight on the gas permeation performance of functionalized-ionic liquids with the [C2mim]+ cation. [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] single gas separation performance towards CO2, N2, and CH4 at T = 293 K and T = 308 K were measured using the time-lag method. Assessing the CO2 permeation results, [C2mim][CF3BF3] showed an undermined value of 710 Barrer at 293.15 K and 1 bar of feed pressure when compared to [C2mim][BF4], whereas for the [C2mim][CF3SO2C(CN)2] IL an unexpected CO2 permeability of 1095 Barrer was attained at the same experimental conditions, overcoming the results for the remaining ILs used for comparison. The prepared membranes exhibited diverse permselectivities, varying from 16.9 to 22.2 for CO2/CH4 and 37.0 to 44.4 for CO2/N2 gas pairs. The thermophysical properties of the [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] ILs were also determined in the range of T = 293.15 K up to T = 353.15 K at atmospheric pressure and compared with those for other ILs with the same cation and anion's with similar chemical moieties.

Recovery of ß-carotene from pumpkin using switchable natural deep eutectic solvents.

The aim of the present research was to develop green and sustainable extraction procedure for ß-carotene recovery from pumpkin. A series of hydrophobic natural deep eutectic solvents (NADESs) based onfatty acids were prepared to establish high extraction efficiency of ß-carotene and to increase stability of extracted carotenoids from the pumpkin. To intensify extraction process, NADES composed of C8 and C10 fatty acids (3:1) was selected and coupled with ultrasound assisted extraction. Response surface methodology and artificial neural network model (ANN) model was adopted to analyze significance of extraction parameters demonstrating high prediction levels of the ß-carotene yield, experimentally confirming the maximum ß-carotene content of 151.41 µg/mL at the optimal process condition. Extracted carotenoids in the optimal NADES extract have shown high stability during the storing period of 180 days. A switchable-hydrophilicity eutectic solvent system has been introduced as a successful way to recover extracted carotenoids from the NADES solvent. It was capable of precipitating 90% of carotenoids present in the extract. The proposed procedure is simple, easily scalable and has minimal impact on operators and the environment.

Beneficial and detrimental effects of choline chloride-oxalic acid deep eutectic solvent on biogas production.

Deep eutectic solvents (DES), a new class of alternative solvents, have recently been used in the pre-treatment of lignocellulosic biomass. Due to the ability to dissolve phenolic compounds, they have been efficiently applied as delignification agents. However, to extend DES application to bioprocesses, such as Anaerobic Digestion (AD), their toxicity to microbial consortia must be evaluated. In this work, an effective delignifying DES, composed of choline chloride (ChCl) and oxalic acid (OA) (1:1) was prepared and its effect evaluated, for the first time, in biogas production. Results show that the presence of DES had both beneficial and detrimental effects on the anaerobic consortium, depending on its concentration. In the concentration range of 0.3-12.5 g/L, the presence of DES led to a lag-phase of 1 to 8 d as the DES concentration increased. However, after the lag-phase has been surpassed, DES up to a concentration of 12.5 g/L improved the biogas production, reaching an accumulated biogas volume three times higher than the control assay for the concentration of 12.5 g/L. For the highest DES concentrations (19.8-78.1 g/L), the biogas production was inhibited. The assays performed with DES components alone have indicated that OA at 3.2 g/L was the main responsible for the inhibition of biogas production (50% less biogas produced than the control). ChCl at 4.9 g/L has not presented a lag-phase and produced an accumulated biogas volume like the control assay (1200 mL for 30 d incubation). This work points out that ChCl:OA DES may be used in the delignification of biomass further submitted to AD, provided the inhibitory concentrations of OA are not achieved.

Mesoporous silica nanoparticles with manganese and lanthanide salts: synthesis, characterization and cytotoxicity studies.

Several organic salts based on the combination of two different choline derivative cations and MnCl3-, GdCl4- and TbCl4- as anions were immobilized in mesoporous silica nanoparticles (MSNs) by a two-step synthetic method. Firstly, MSNs were functionalized with choline derivative cations with chloride anions and then the metals were incorporated by the reaction of the chloride with the respective metal chloride salts. These nanomaterials were fully characterized by different characterization techniques such as 1H-NMR, FT-IR, elemental analysis, TEM, TGA, N2 adsorption, XRD and DLS. These characterization data were important to confirm the successful functionalization of the nanomaterials and to access their textural properties and colloidal stability. The final materials were also characterized by ICP-MS that indicated the metal contents. The cytotoxicity profile was evaluated in four different cell lines (3T3, 293T, HepG2 and Caco-2), which shows some relevant differences between the metal organic salts and their immobilized analogues.

Tuning the miscibility of water in imide-based ionic liquids.

Liquid-liquid phase behavior measurements were performed for binary mixtures of water and ionic liquids (ILs) containing the same 1-ethyl-3-methylimidazolium ([C2mim]+) cation and different imide-based anions, having symmetric (bis(fluorosulfonyl)imide ([FSI]-)) or asymmetric structures (2,2,2-trifluoromethylsulfonyl-N-cyanoamide ([TFSAM]-) and 2,2,2-trifluoro-N-(trifluoromethylsulfonyl)acetamide ([TSAC]-)). An inversion of phase behavior was observed: while below ∼298 K, the miscibility of water in the studied ILs increases according to the order [C2mim][TSAC] < [C2mim][FSI] < [C2mim][NTf2], for temperatures above ∼303 K, the reverse trend is observed [C2mim][NTf2] < [C2mim][FSI] < [C2mim][TSAC]. In turn, above ∼306 K the [C2mim][TFSAM] is completely miscible with H2O in all ranges of concentrations. The obtained results also revealed an unusual water solubility variation of 11% in [C2mim][FSI], and 20% in [C2mim][TSAC], when the system temperature was changed by less than 1 K, around 298 K and 301 K, respectively. Molecular Dynamics (MD) simulations were used to understand the IL-water interactions and rationalize the experimental observations. These results suggested that the miscibility trends are mainly related to the ability of the water molecules to form water-anion and water-water aggregates in solution.

Vapor Pressure Assessment of Sulfolane-Based Eutectic Solvents: Experimental, PC-SAFT, and Molecular Dynamics.

Since their discovery, deep eutectic solvents (DES) have been explored in multiple applications. However, the complete physicochemical characterization is still nonexistent for many of the proposed and used DES. In particular, vapor pressure, which is a crucial property for the application of DES as solvents, is very rarely available. In this work, the measurement of the total and partial pressures of two sulfolane-based DES, tetrabutylammonium bromide:sulfolane and tetrabutylphosphonium bromide:sulfolane, in several proportions, from 40 to 100 °C and atmospheric pressure, was performed using headspace gas chromatography mass spectrometry, HS-GC-MS. A large decrease on the total pressure was recorded which, together with the finding that total pressures showed negative deviations from Raoult's law, is indicative of the favorable, strong interactions between the two components within the DES. Additionally, the study of vapor pressure change with DES molar composition was carried out, and surprisingly, the existence of inflection points in the pressure curve was observed. Experimental results were modeled using the PC-SAFT equation of state, and in addition, MD simulations were performed to provide a molecular understanding of the pressure data. Considering the different results and insights obtained from the used strategies, it can be concluded that both DES systems have especially strong interactions between salt and sulfolane, at high sulfolane content, due to the different structural rearrangement of the liquid state.

Enzyme-assisted extraction of carotenoids and phenolic compounds from sunflower wastes using green solvents.

The aim of this work is to develop an optimized enzymatic assisted extraction methodology to extract carotenoids and phenolic compounds from sunflower wastes (petals and florets) using natural hydrophobic green solvents. Several natural green hydrophobic solvents were used as well as natural hydrophobic eutectic solvents composed of d,l-menthol and different acids, with different hydrophobicity. The multi-enzyme complex Viscozyme® was used to disrupt the cell wall of petals and disc florets. The extracted carotenoids content into the hydrophobic phase was quantified using UV-Vis spectrophotometry and the carotenoids profile was studied using high-performance liquid and thin layer chromatography. The amount of total sugars in the aqueous phase was also analyzed using the dinitrosalicylic acid (DNS) method to infer about the enzymatic action in cell wall. Phenolic compounds also in the aqueous phase were analyzed by Folin Denis method. The eutectic solvent d,l-menthol:d,l-lactic acid (M:HLac) (1:2) was the best solvent for extraction of carotenoids from sunflower wastes, with 147 ppm of carotenoids extracted, in comparison to 115 ppm obtained with the standard solvent, n-hexane. In what concerns phenolic compounds, M:HLac was again better than the standard solvent. The use of the multi-enzyme complex Viscozyme® had different responses, depending on the solvent tested. For the green solvent M:HLac, the enzyme improved the carotenoids extraction, achieving 335 ppm of carotenoids in the extract. The role of enzyme, solvent, water and sunflower quantity in the carotenoid extraction was evaluated and optimized through a central composite rotatable design (CCRD), using the M:HLac as solvent. According to the analysis of CCRD, the most efficient extractions were carried out using more solvent and less raw material, whose best result reached 1449 mg carotenoids/100 g biomass ppm of carotenoids. This work emphasizes the possibility of developing more sustainable enzyme-assisted separation processes, through the substitution of toxic solvents with natural, environmentally friendly, solvents.

Thin Porous Poly(ionic liquid) Coatings for Enhanced Headspace Solid Phase Microextraction.

In this contribution, thin poly(ionic liquid) (PIL) coatings with a well-defined pore structure built up from interpolyelectrolyte complexation between a PIL and poly(acrylic acid) (PAA) were successfully used for enhanced solid phase microextraction (SPME). The introduction of porosity with tunable polarity through the highly versatile PIL chemistry clearly boosts the potential of SPME in the detection of compounds at rather low concentrations. This work will inspire researchers to further explore the potential of porous poly(ionic liquid) materials in sensing and separation applications.

Molecular Dynamics Insights and Water Stability of Hydrophobic Deep Eutectic Solvents Aided Extraction of Nitenpyram from an Aqueous Environment.

In recent times, deep eutectic solvents (DES) have received attention as an extractive media for separations. In this work, the water stability of eight menthol-based DESs and two tetrabutylammonium chloride (N4444Cl) based DESs with organic acid-based hydrogen bond donors (HBD) at a temperature of 298.15 K and atmospheric pressure were studied. dl-Menthol and N4444Cl were considered as the hydrogen bond acceptors (HBA). Molecular dynamics simulation (MD) was used as a tool to examine the distribution of molecules of DES and water in either phase. The intermolecular nonbonded interaction among the species of the systems was analyzed with radial distribution function, interaction energy, and hydrogen-bonding analysis to understand the stability of DESs in an aqueous medium. The results showed that the strong hydrogen bond plays a crucial role in the water stability of the DES. The degree of hydrogen bonding in HBD-water in terms of HBDs obtained by MD simulation can be presented in the order of acetic acid > levulinic acid > butanoic acid > pyruvic acid > hexanoic acid > octanoic acid > decanoic acid > dodecanoic acid. The strength of the hydrogen bond was attributed to the structure of solvents and the alkyl chain length of the HBD group. Overall, the order of stability of DES in water based on a "relative stability factor" was found as dl-menthol:acetic acid (1:1) < dl-menthol: levulinic acid (1:1) < dl-menthol:butanoic acid (1:1) < dl-menthol:pyruvic acid (1:2) < dl-menthol:hexanoic acid (1:1) < dl-menthol:octanoic acid (1:1) < dl-menthol: decanoic acid (1:1) < dl-menthol:dodecanoic acid (2:1). The transfer of molecules in the system from the aqueous phase to the DES rich phase was analyzed with the help of mean-square displacement and diffusion-coefficients. dl-Menthol and organic acids starting from octanoic acid and higher ones can be used in aqueous systems as solvents. Finally, dl-menthol:octanoic acid (1:1) -based DES was used to benchmark and predict the extraction efficiency of a pesticide (nitenpyram) from an aqueous feed. Hydrogen bond analysis demonstrated higher interactions of nitenpyram with dl-menthol and octanoic acid as compared to water. The MD simulation of the ternary system consisting of DES, water, and nitenpyram showed encouraging results, and gave an excellent agreement with experimental literature data in terms of extraction efficiency (∼42 to 46.7%) and distribution ratio (0.72).

Antimicrobial Activities of Highly Bioavailable Organic Salts and Ionic Liquids from Fluoroquinolones.

As the development of novel antibiotics has been at a halt for several decades, chemically enhancing existing drugs is a very promising approach to drug development. Herein, we report the preparation of twelve organic salts and ionic liquids (OSILs) from ciprofloxacin and norfloxacin as anions with enhanced antimicrobial activity. Each one of the fluoroquinolones (FQs) was combined with six different organic hydroxide cations in 93-100% yield through a buffer-assisted neutralization methodology. Six of those were isomorphous salts while the remaining six were ionic liquids, with four of them being room temperature ionic liquids. The prepared compounds were not toxic to healthy cell lines and displayed between 47- and 1416-fold more solubility in water at 25 and 37 °C than the original drugs, with the exception of the ones containing the cetylpyridinium cation. In general, the antimicrobial activity against Klebsiella pneumoniae was particularly enhanced for the ciprofloxacin-based OSILs, with up to ca. 20-fold decreases of the inhibitory concentrations in relation to the parent drug, while activity against Staphylococcus aureus and the commensal Bacillus subtilis strain was often reduced. Depending on the cation-drug combination, broad-spectrum or strain-specific antibiotic salts were achieved, potentially leading to the future development of highly bioavailable and safe antimicrobial ionic formulations.

Dual nanofibrillar-based bio-sorbent films composed of nanocellulose and lysozyme nanofibrils for mercury removal from spring waters.

The present study explores the preparation of dual nanofibrillar-based bio-sorbent films composed of cellulose nanofibrils (CNFs) and lysozyme nanofibrils (LNFs) for application in the removal of Hg(II) from aqueous solutions. The free-standing films were fabricated via simple vacuum filtration of water suspensions of CNFs and LNFs and disclose good mechanical and thermal properties. The Hg(II) removal efficiency was evaluated by atomic fluorescence spectroscopy in ultra-pure and natural spring waters contaminated with environmental realistic levels of mercury (50 µg L-1). The removal efficiency is pH-dependent reaching a maximum of 99 % after 24 h at a pH value close to the isoelectric point of the protein. Under the experimental conditions, the sorption kinetics are well described by the pseudo-second-order and Elovich models, suggesting a chemisorption mechanism. These results demonstrate the ability of the dual nanofibrillar-based films to remove Hg(II) from water samples reaching a residual concentration lower than the guideline value for water intended for human consumption (1 µg L-1). Therefore, the CNFs/LNFs bio-sorbents might be a solution to treat low-concentrated mercury-contaminated waters.

Neat ionic liquids versus ionic liquid mixtures: a combination of experimental data and molecular simulation.

Simple mixtures of ionic liquids (IL-IL mixtures) can become a promising approach for the substitution of task-specific ILs. Such a concept was explored in this article by comparison of the thermophysical properties of neat 1-ethyl-3-methylimidazolium 2,2,2-trifluoromethylsulfonyl-N-cyanoamide, [C2mim][TFSAM], and equimolar mixtures of two structurally similar ILs having more common ions. Molecular dynamics (MD) simulations were additionally used to further highlight structural aspects of these systems at a molecular level.

Poly(ionic liquid) embedded particles as efficient solid phase microextraction phases of polar and aromatic analytes.

In this work, a facile preparation of SPME fibers with increased surface area is presented. The SPME fibers were prepared by grinding poly(ionic liquids) (PILs) to obtain particles of 1-16 µm and, with the aid of a silicon adhesive, attach these particles to a steel wire support. Three different PILs, poly(1-vinyl-3-benzylimidazolium-co-styrene bromide) [poly(ViBnIm-co-Sty Br)], poly(1-vinyl-3-benzylimidazolium-co-styrene bis(trifluoromethanesulfonyl)imide) [poly(ViBnIm-co-Sty TFSI)] and poly(diallyldimethylamine bis(trifluoromethanesulfonyl)imide) [poly(Pyrr11 TFSI)], were used. The first two PILs were obtained by reversible addition-fragmentation chain transfer polymerization followed by metathesis reactions. The thicknesses of the prepared fibers were found to be 19 ±â€¯4 µm and 85% of the particles used have diameters between 2 and 10 µm. The prepared fibers were tested by performing the headspace extraction of two standard solutions, one containing a mixture of alcohols with different chain lengths, and the other a mixture of aromatic compounds, leading to sorption times of 10 - 15 min due the large surface area attained with this method. PILs with aromatic moieties containing the bromide anion showed high selectivity towards polar compounds, due to the hydrogen basicity of the anion, and also towards aromatic analytes, due to the aromatic nature of styrene moieties and the cation pendant groups. The limits of detection fall in the sub ppb level, while relative standard deviations and reproducibility from fiber-to-fiber found maximums of 16.2% and 22.5%, respectively. Furthermore, the PIL based fibers showed up to 90% higher extraction efficiencies compared to the commercial fibers of polydimethylsiloxane and polyacrylate.

Quest for Green-Solvent Design: From Hydrophilic to Hydrophobic (Deep) Eutectic Solvents.

Deep eutectic solvents (DESs) consist of a mixture of two or more solid components, which gives rise to a lower melting point compared to the starting materials. Until recently only hydrophilic DESs were available, and despite their revolutionary role in the alternative-solvents field, important issues in chemistry, and chemical engineering (such as water-related problems and the replacement of toxic volatile organic compounds) could not be tackled. Hydrophobic (deep)-here in parenthesis due to the different depths of the eutectic melting points-eutectic solvents are a subclass of DESs where both components are hydrophobic. The low toxicity, high biodegradability, and straightforward preparation without further purification steps of naturally occurring low-cost compounds are among the key advantages. Although research on hydrophobic DESs is scarce (the first report was only published in 2015), some interesting features and applications have been reported and deserve to be evaluated and comparisons established. This Minireview is divided into two parts: The first part provides a brief general introduction to DESs and the second part discusses the nomenclature using solid-liquid phase diagram analysis, chemical stability, thermophysical properties comparison, and finally the most important emerging fields of application.

Towards Biohydrogen Separation Using Poly(Ionic Liquid)/Ionic Liquid Composite Membranes.

Considering the high potential of hydrogen (H2) as a clean energy carrier, the implementation of high performance and cost-effective biohydrogen (bioH2) purification techniques is of vital importance, particularly in fuel cell applications. As membrane technology is a potentially energy-saving solution to obtain high-quality biohydrogen, the most promising poly(ionic liquid) (PIL)⁻ionic liquid (IL) composite membranes that had previously been studied by our group for CO2/N2 separation, containing pyrrolidinium-based PILs with fluorinated or cyano-functionalized anions, were chosen as the starting point to explore the potential of PIL⁻IL membranes for CO2/H2 separation. The CO2 and H2 permeation properties at the typical conditions of biohydrogen production (T = 308 K and 100 kPa of feed pressure) were measured and discussed. PIL⁻IL composites prepared with the [C(CN)3]- anion showed higher CO2/H2 selectivity than those containing the [NTf2]- anion. All the membranes revealed CO2/H2 separation performances above the upper bound for this specific separation, highlighting the composite incorporating 60 wt% of [C2mim][C(CN)3] IL.

Supramolecular hydrogel based on a sodium deep eutectic solvent.

A supramolecular hydrogel based on a metal-containing deep eutectic solvent (DES) is presented here for the first time. The phase diagram of the DES-based hydrogel was drawn and its rheological properties were determined.

Tuning lysozyme nanofibers dimensions using deep eutectic solvents for improved reinforcement ability.

Deep eutectic solvents (DESs), a novel generation of solvents, have recently been described as efficient and timesaving fibrillation agents for proteins. In this context, the present work aims at assessing the effect of the hydrogen bond donor (HBD) of cholinium chloride ([Ch]Cl):carboxylic acid based DESs on the dimensions (length and width) of lysozyme nanofibers (LNFs). Mono-, di- and tri-carboxylic acids (acetic, lactic, levulinic, malic and citric acids) were used to prepare different DES formulations, which were successfully used on the fibrillation of lysozyme. The results showed that the carboxylic acid (i.e. the HBD) plays an important role on the fibrillation efficiency and on the length of the ensuing LNFs with aspect-ratios always higher than those obtained by fibrillation with [Ch]Cl. The longest LNFs were obtained using lactic acid as the HBD with an average length of 1004 ±â€¯334 nm and width of 31.8 ±â€¯6.8 nm, and thus an aspect-ratio of ca. 32. The potential of these protein nanofibers as reinforcing additives was evaluated by preparing pullulan (PL)-based nanocomposite films containing 5% LNFs with different aspect-ratios, resulting in highly homogenous and transparent films with improved mechanical performance.