Dr. Cabezas-Cornejo, René

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.

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.

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 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.

In this work, the factors that determine a high or low extraction performance when using ionic liquids (ILs) as diluents in the solvent extraction of Rhenium (Re(VII)) from aqueous solutions were studied by means of experiments, quantum chemical (QC) calculations, and COSMO-RS. For this purpose, kerosene and the ionic liquids (ILs) 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [C4C1im][Tf2N], or 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide [C8C1im][Tf2N] were used as diluents to determine de effect of alkyl chain of ILs, and two high molecular weight amines: trioctylamine (TOA) and Alamine 336 (Al336) were used as the extractants. The results indicated that the so-called reference extracting phase TOA in kerosene achieved 99% extraction percentages. On the contrary, a lower performance was observed when replacing kerosene with any of both ILs. This reduction was mainly due to two reasons. First, the IL dissociates where the cation takes part in the formed complex, hindering the TOA-perrhenate bonding, and second, the formed complex that contains IL cations shows poor dissolution in the diluent phase. This could be avoided by means of long alkyl chain imidazolium bis(trifluoromethylsulfonyl)imide-based ILs. Additionally, operating parameters such as equilibrium stages and concentration of the stripping agent were studied. Promising results were obtained by replacing TOA with Al336 dissolved in the IL [C8C1im][Tf2N], showing very similar results with the reference extracting phase.

The selective removal of butanol from a fermentation broth continues to be a challenge for the generation of alternative biofuels. In this work, a continuous extraction of a model acetone-butanol-ethanol (ABE) solution, using a perstraction membrane system with ionic liquid [omim][Tf2N] as extractant phase coupled to a vacuum extraction system of the extractant phase has been studied. Perstraction assays were carried out using a tubular polydimethylsiloxane (PDMS) membrane to quantify the extraction percentage and transmembrane fluxes of butanol, acetone, ethanol, and water. The results indicate that the transmembrane fluxes of butanol were particularly high considering that the PDMS membrane used in the experiments was relatively thick (3.175 mm). The highest average flux of butanol was obtained at 37 °C using [omim][Tf2N] as extractant reaching a value of [kg h−1 m−2] with a separation performance showing a highest butanol/water selectivity value equal to 6.73. The mass transfer model based on the resistance-in-series theory, demonstrated a good correlation to the experimental data verifying that the membrane generates a higher resistance to mass transfer (∼98 %). This perstraction technique combined with the use of ILs could allow to design a wide range of separation processes to purify a large variety of molecules. Additionally, the perstraction process could be considered a good alternative for the selective separation of fermentation or reaction products with high commercial value.