Research Outputs
Triazolium‐based ionic liquids supported on alumina as catalysts to produce 5‐HMF from fructose
The dehydration of fructose to selectively produce 5‐HMF was catalytically developed in a new type of ionic liquids based on triazoles supported on alumina (Al2O3). The synthesis of triazoles by 1,3‐dipolar cycloaddition allows for creating a tailor‐made triazole, that was eventually used to design catalysts based on triazolium‐based ionic liquids. In this work, four catalysts based on triazolium‐ionic liquids supported on Al2O3 were synthesized to produce 5‐HMF from fructose in DMSO as the reaction solvent. According to their molecular structure, the catalysts were tagged as TR1/Al2O3, TR1‐HSO4/Al2O3, TR2/Al2O3, and TR2‐HSO4/Al2O3.
Analysis of microwave-assisted heating and water extraction from imidazolium and phosphonium based ionic liquids
Ionic liquids have attracted widespread attention due to their low melting points, low vapor pressure, and non-flammability. However, their application at industrial scale is uncommon due to high costs and low recovering efficiency of the ionic liquids within the process. To reduce the costs and environmental effects of ionic liquids, this study proposes to use industrial microwave irradiation to recover eight different ionic liquids from water. The heating kinetics and identification between dielectric and convective heat properties were studied. Imidazolium-based ionic liquids showed the best results, reaching higher temperatures in shorter periods of time. Ionic liquid (bis(trifluoromethylsulfonyl) trihexyl(tetradecyl) phosphonium imide ([P6,6,6,14][Tf2N]) reached a temperature of 398 K in 360 s). On the other hand, the ionic liquid (1-butyl-3-methylimidazolium methylsulfate ([bmim][CH3OSO3]) reached a temperature of 417 K in 150 s). the ionic liquid Microwave heating experiments (water/ionic liquids) demonstrated a 90% recovery in ∼200 s for 1-octyl-3-methylimidazolium chloride ([omim][Cl]). Finally, the time used to heat-up ionic liquids with microwave irradiation was 15 times shorter than the time employed with vacuum-assisted distillation. Therefore, microwave-assisted heating has shown to be an excellent form to heat ionic liquids to decrease the cost of the extraction process and improve their reusability.
Succinic acid recovery from a glycerol-based solution using phosphonium ionic liquids supported by COSMO-RS
Succinic acid has been considered a promising chemical building block that can be bio-produced using renewable resources. However, one of the biggest challenges in the bioproduction of this acid is the extraction and purification process. Currently, to extract and improve the purity of the produced succinic acid, a liquid-liquid extraction using organic solvents and extractants is performed. In this work, a liquid-liquid extraction of succinic acid from a model fermentation solution of Yarrowia lipolytica yeast broth (succinic acid + glycerol + water) is studied. The liquid-liquid extraction was carried out using hydrophobic phosphonium-based ionic liquids as extractants, for a 1:1 phase-volume ratio during 24 h at two different temperatures (298.15 K and 310.15 K) measuring the differences in the concentration of succinic acid and glycerol in the aqueous feed phase after 24 h to quantify the extraction percentage and, the succinic acid / glycerol selectivity. To obtain the succinic acid /water selectivity, the water concentration in the IL phase was calculated using Karl Fischer titration. With an extraction percentage of 78.4% for succinic acid and, a selectivity of 103 and 157 respectively for succinic acid /water and succinic acid /glycerol at 310.15 K, the best studied ionic liquid was [P6,6,6,14][PHOS] being 10 times higher than octanol, which is commonly used as a comparative conventional solvent. On the other hand, a molecular simulation of liquid-liquid extraction generated in COSMO-RS, allowed to validate the experimental results, also indicating that the strong hydrogen bond interactions of [P6,6,6,14][PHOS] and succinic acid were responsible for the excellent values obtained. Finally, the dissolved succinic acid in the organic phase was easily removed with an ultra-pure water striping using liquid-liquid extraction at 298.15 K for 40 min with a 1:1 phase-volume ratio.
Challenges and possibilities of deep eutectic solvent-based membranes
Deep eutectic solvents (DES) are a category of a new class of solvents that can overcome some of the main drawbacks of typical solvents and ionic liquids (ILs). DES have been widely investigated and applied by the research community in several applications since their invention. Over the past years, the use of DES has been directed to the production of new materials and items for new products and processes. This is the case for the implementation of DES in various fields of chemical engineering directed to separations. DES have been very recently initiated to be combined into membranes for membrane processes. In this regard, this Review timely elucidates the current progress in utilizing this new generation of solvents in membrane preparation. In this work, different techniques, methods, and strategies for incorporating DES into polymer membranes for different concepts of membranes according to the final application have been reviewed. Particular emphasis has been devoted to the most relevant development works and results. After the current literature was analyzed, the main challenges and possibilities of DES in membranes were declared.
Development of PLA suture materials by extrusion, electrospinning and supercritical CO2 impregnation of ibuprofen and naproxen
Suture materials based on poly (lactic acid) (PLA) were developed by means of two different methods: extrusion and electrospinning, which were followed by a supercritical CO2 impregnation treatment. Both suture materials obtained by these techniques were impregnated with naproxen and ibuprofen using supercritical CO2 as impregnation medium. The impregnation assays were carried out at two different pressures (12 and 15 MPa), a temperature of 40 °C and, a depressurization rate of 1 MPa/min. Depending on the drugs incorporated into the suture materials, the concentrations varied from 5.60 to 26.73 wt%. The addition of both drugs and, the preparation process itself caused different changes in the structural and thermal properties of the final suture materials. Finally, tests to quantify the kinetic release of both drugs were carried out in vitro by using a Franz diffusion cell, obtaining the concentration profiles of delivered compounds as a function of the time.
COSMO-RS evaluation as a tool for prediction of solvents in dispersive liquid-phase microextraction: Evaluation of conventional solvents and ionic liquids as extractants
This work assesses the prediction capability of COSMO-RS for solvent selection in dispersive liquid phase microextraction systems. The assessment is performed by comparing experimental partition ratios from previous works and calculated ones for different systems, including pesticides, herbicides, polyaromatic aromatic hydrocarbons, and halogen-containing pollutants from water samples. Results indicate that COSMO-RS mainly overestimates the partition ratios. Despite this, a priori analysis was carried out for conventional solvents used as extractants. Results showed that for pesticides and herbicides, COSMORS predictions agree just for a few extractants. For polyaromatic hydrocarbons (PAHs), the ring structure is a crucial parameter in extractants’ selection, and for Halogenated pollutants, the halogen content and kind of substitution are crucial to correct trend prediction. Besides this, ILs also were studied, finding that COSMO-RS overestimates the use of ILs, and higher deviations are found for longer alkyl chain cations. However, the Dichlorodiphenyltrichloroethane (DDT) metabolite extraction with ILs is well predicted. Dispersants were also evaluated, but depending on the kind of pollutant, different deviations were found.
Design of a perstraction-based extraction system for the removal of polychlorinated biphenyls from bovine milk via COSMO-RS: Membrane screening
This study theoretically and experimentally selected a membrane for application in a perstraction process for PCB-77 removal using COSMO-RS predictions. To validate COSMO-RS, different studies of pollutants were analysed and compared using the activity coefficient computed by COSMO-RS, and the experimental reported results were in accordance with the predicted thermodynamic parameters. Then, the main components in milk were optimised using TMoleX® to screen for different polymers. The screening revealed that polychloroprene, polybutadiene, and polyoctylmethylsiloxane had the lowest activity coefficients for PCB-77, and a high selectivity for other components in milk. The results obtained by COSMO-RS were compared with experiments using nitrocellulose, polydimethylsiloxane, polyether sulfones, and polystyrene, where the simulated values were validated. Finally, analysis of the membrane structures revealed that the best membrane to be applied in perstraction is polyoctylmethylsiloxane.
Hydrophobic eutectic solvents for the selective solvent extraction of molybdenum (VI) and rhenium (VII) from a synthetic pregnant leach solution
In this work, a study on the selective solvent extraction (SX) of molybdenum (Mo) and rhenium (Re) from a synthetic pregnant leach solution (PLS) has been carried out using nine different hydrophobic eutectic solvents (HES). Experiments were carried out using pure HES to evaluate the selective extraction and the subsequent stripping of these metal ions; then, the best HES was dissolved in kerosene to study the SX stoichiometry. Results indicated that only TOPO-based and N8881-Cl-based HES did not form emulsions, third phases or precipitates. These HES achieved a selective extraction because these obtained almost a 100% extraction towards Mo and Re from the PLS and very low extractions for Copper (Cu) and Iron (Fe) in one equilibrium stage. The stripping experiments showed that 95% of Mo and 22% of Re were stripped out from the loaded TOPO-based HDES, respectively, opening the possibility for the selective stripping of the metal species for further purification. Finally, the extraction stoichiometry was proposed based on an experimental slope analysis and the measurement of cations and anions transferred into the aqueous phase in which HES acts as a neutral extractant in the complexation of the Mo and Re salts. These promising results suggest that HES could be attractive for more sustainable mining industry.
Separation of biobutanol from fermentation solutions by perstraction using [P6,6,6,14][Tf2N] as receiving phase: Phase temperature analysis
In this work, the perstraction process was implemented to separate butanol, acetone and ethanol from a model fermentation aqueous solutions using [P6,6,6,14][Tf2N], which is a highly hydrophobic phosphonium based ionic liquid as receiving phase. Perstraction assays were carried out using a flat sheet dense membrane of polydimethylsiloxane (PDMS) to quantify the extraction percentage, transmembrane fluxes of butanol, water and butanol/water selectivity focused on the effect of the temperature difference between the feed and extractant phase. The results indicate that the fluxes of butanol were particularly high considering the PDMS membrane used in the experiments was relatively thick (160 µm). The highest average flux of butanol was obtained when the temperature of the aqueous phase was 60 °C and the temperature of the organic phase was 30 °C reaching a value of 6.3 · 10-3 kg h-1 m-2, showing a butanol-water selectivity of 58.2, generated by the different sensitivity to temperature of the vapor pressure of both compounds. Finally, this disruption technique combined with ILs could allow the design of a wide range of separation processes for purify a wide variety of molecules. In addition to this, the perstraction process could be considered as a good alternative for the selective separation of fermentation or reaction products with high commercial value.
Development of silicone-coated hydrophobic deep eutectic solvent-based membranes for pervaporation of biobutanol
Hydrophobic Deep Eutectic Solvents (HDES) are considered a relatively novel class of solvents, which show perfect features to incorporate them in pervaporation membranes. Composite HDES membranes offer a separation media, which shows a faster molecular diffusion than polymeric membranes, combining the best properties of liquid and polymer membranes, such a high selectivity with high burst pressure and durability. In this work, the separation of acetone–butanol–ethanol mixtures (ABE) from aqueous solutions, is carried out by pervaporation using membranes prepared with HDES lidocaine-thymol (Lidol) and CH3(CH2)8COOH-Thymol (Decadol), coated with two polydimethylsiloxane (PDMS) flat sheet membranes. The composite membranes showed improved results for the butanol/water selectivity compared to the single PDMS layer membrane used as a control. The total flux of butanol obtained with the Lidol-based membrane was 2.93 × 10−3 [kg m−2 hr−1]. The total flux of water was 1.22 × 10−4 [kg m−2 hr−1], showing a selectivity value for butanol/water of 1932, while the control membrane had a selectivity value of 6. The results obtained with the composite membranes exhibited a higher and more stable performance in separating butanol from the ABE solution. The improvement in the selectivity can be explained by the synergic effect of the PDMS coating with the HDES layer.