Dr. Cabezas-Cornejo, René

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.

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.

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.