Browsing by Author "Held, Christoph"

Now showing 1 - 6 of 6
  • No Thumbnail Available
    Item
    Assessing the Effect of Deep Eutectic Solvents on α-Chymotrypsin Thermal Stability and Activity
    (2024) Gajardo-Parra, Nicolás F.; Cea-Klapp, Esteban; Chandra, Anshu; Canales Muñoz, Roberto; Garrido, José Matías; Held, Christoph; Guajardo Ramírez, Nadia Verónica
    Optimizing the liquid reaction phase holds significant potential for enhancing the efficiency of biocatalytic processes since it determines reaction equilibrium and kinetics. This study investigates the influence of the addition of deep eutectic solvents on the stability and activity of α-chymotrypsin, a proteolytic enzyme with industrial relevance. Deep eutectic solvents, composed of choline chloride or betaine mixed with glycerol or sorbitol, were added in the reaction phase at various concentrations. Experimental techniques, including kinetic and fluorometry, were employed to assess the α-chymotrypsin activity, thermal stability, and unfolding reversibility. Atomistic molecular dynamics simulations were also conducted to assess the interactions and provide molecular-level insights between α-chymotrypsin and the solvent. The results showed that among all studied mixtures, adding choline chloride + sorbitol improved thermal stability up to 18 °C and reaction kinetic efficiency up to two-fold upon adding choline chloride + glycerol. Notably, the choline chloride + sorbitol system exhibited the most substantial stabilization effect, attributed to the surface preferential accumulation of sorbitol, as corroborated by the computational analyses. This work highlights the potential of tailoring liquid reaction phase of α-chymotrypsin catalyzed reaction using neoteric solvents such as deep eutectic solvents to enhance α-chymotrypsin performance and stability in industrial applications.
  • No Thumbnail Available
    Item
    (-)-Epicatechin Solubility in Aqueous Mixtures of Eutectic Solvents and Their Constituents
    (2024) Bastias-Barra, Arturo I.; Gajardo-Parra, Nicolas F.; Cea-Klapp, Esteban; Arroyo-Avirama, Andres F.; Garrido, Jose Matias; Held, Christoph; Perez-Correa, Jose R.; Canales, Roberto I.
    (-)-Epicatechin is a polyphenol present in diverse natural sources. It shows positive human health effects, which makes it interesting for the pharmaceutical and food industries. Conventional solvents used for polyphenol extraction are mostly toxic and flammable, leaving unwanted impurities in the final product. Thus, solubility of (-)-epicatechin at 101.3 kPa and 293.15, 303.15, and 313.15 K was experimentally measured in water and binary systems composed of 25 wt % of water + 1,3-propanediol (13PD), glycerol (Gly), and two deep eutectic solvents based on choline chloride as hydrogen-bond acceptor and the previous polyols as hydrogen-bond donors (DES1 and DES2). Solubility results in water were obtained using spectrophotometric and gravimetric methodologies. Overall, (-)-epicatechin solubility varies widely among the studied solvents but only slightly within the experimental temperature range. Solvents in ascending order according to (-)-epicatechin solubility are water < Gly + water < 13PD + water < DES2 + water < DES1 + water. The solubility of (-)-epicatechin is significantly enhanced by introducing choline chloride into the investigated hydrogen-bond donors (HBDs) at a molar ratio of 1:3, accompanied by 25 wt % water. Perturbed-chain statistical associating fluid theory (PC-SAFT) solubility calculations were in quantitative agreement with experimental data.
  • Thumbnail Image
    Item
    Impact of deep eutectic solvents and their constituents on the aqueous solubility of phloroglucinol dihydrate
    (2021) Gajardo-Parra, Nicolas F.; Do, Hoang T.; Yang, Mengyi; Perez Correa, Jose Ricardo; Garrido, Jose Matias; Sadowski, Gabriele; Held, Christoph; Canales, Roberto, I
  • No Thumbnail Available
    Item
    Improving the separation of guaiacol from n-hexane by adding choline chloride to glycol extracting agents
    (2022) Arroyo-Avirama, Andres F.; Ormazabal-Latorre, Sebastian; Jogi, Ramakrishna; Gajardo-Parra, Nicolas F.; Pazo-Carballo, Cesar; Ascani, Moreno; Virtanen, Pasi; Matias Garrido, Jose; Held, Christoph; Maki-Arvela, Paivi; Canales, Roberto, I
    Bio-oil is an important candidate to replace oil-derived products since it origins from renewable sources such as biomass. However, oxygenated bio-oil-based compounds require upgrading and further separation and purification for obtaining valuable compounds. Guaiacol is an important lignin derivative obtained from bio-oil, and it is a precursor for obtaining high-value-added molecules through heterogeneous catalysis. Alkanes are typical solvents for the guaiacol catalytical upgrading, so it is important to understand the extraction of guaiacol or guaiacol-like molecules from alkanes systems. This work reports the potential applicability of glycols and their corresponding eutectic mixtures with choline chloride as liquid-liquid extracting agents of guaiacol from n-hexane. The liquid-liquid equilibrium of six ternary systems composed of guaiacol +n-hexane + glycol or eutectic mixture is reported at 313.15 K and 101.3 kPa. Glycols selected as hydrogen bond donors were ethylene glycol, 1,2-propanediol, and 1,4butanediol, while choline chloride was chosen as the hydrogen bond acceptor for preparing three eutectic mixtures using the glycols mentioned earlier. Density and viscosity of pure components and binary mixtures composed of guaiacol + glycols or guaiacol + eutectic mixture were measured at temperatures between 293.15 K and 333.15 K at 101.13 kPa. Density and liquid-liquid equilibrium data were modeled with PC-SAFT, and binary parameters were only used between the studied glycols and guaiacol. The results showed that the constituents of the eutectic mixtures did not distribute in the n-hexane phase, which was validated by NMR and GC. The viscosity of the pure components was correlated using PCSAFT + Free Volume Theory, which allowed predicting the viscosity of mixtures by using binary parameters that were fitted to viscosity-independent data. The results obtained show that there is a high affinity between the guaiacol and the eutectic mixtures, based on observations about the negative excess volumes and the liquid-liquid equilibria. The eutectic mixtures are better for extracting guaiacol than their respective glycol-based constituents since they have higher selectivity and distribution coefficients and are larger miscibility gaps with the n-hexane phase compared to the studied glycols.(c) 2022 Elsevier B.V. All rights reserved.
  • Thumbnail Image
    Item
    Predicting the Solubility of CO2 in Toluene plus Ionic Liquid Mixtures with PC-SAFT
    (2017) Canales Muñoz, Roberto; Held, Christoph; Lubben, Michael J.; Brennecke, Joan F.; Sadowski, Gabriele
  • Thumbnail Image
    Item
    Separation of furfuryl alcohol from water using hydrophobic deep eutectic solvents
    (2023) Cea Klapp, Esteban; Arroyo Avirama, Andrés Felipe; Ormazábal Latorre, Sebastián Alejandro; Gajardo Parra, Nicolás F.; Pazo Carballo, César Alexander; Quinteros Lama, Héctor; Marzialetti, Teresita; Held, Christoph; Canales Muñoz, Roberto; Garrido, José Matías
    Furfuryl alcohol (FA) is an important organic chemical feedstock that must be separated from water to upgrade it into high-value-added products. Since FA forms an azeotrope with water, liquid-liquid extraction is a suitable option for separating both compounds. This work evaluates the separation of FA from water using hydrophobic deep eutectic solvents (DES). Three DES were prepared using menthol, thymol, and octanoic acid by combining them in molar ratio as follows: thymol + octanoic acid (1:2), menthol + octanoic acid (1:2), and thymol + menthol (1:1). Experimental liquid-liquid equilibria (LLE) of ternary systems water + FA + DES measured at 313.15 K and 101.13 kPa were used to determine the distribution coefficient and selectivity values for FA when using each DES. The experimental results were compared with molecular dynamics (MD) using Martini 3 force field and modeled using Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) without any adjustable binary parameters. According to the results, selectivities and distribution coefficients using hydrophobic DES have comparable values to traditional volatile organic compounds (VOCs) used to separate FA from water. In general, DES shows better distribution coefficients compared with typical organic solvents. According to the results, a good alternative would be menthol + octanoic acid (1:2) or thymol + menthol (1:1) to replace typical VOCs. MD and PC-SAFT provide accurate estimations for ternary LLE in the range of examined thermodynamic conditions, which confirms the predictive consistency of both approaches. Microscopic properties computed with MD simulations evidence a surface activity or absolute adsorption of FA in the interfacial region, which is correlated with favorable distribution coefficients and selectivities.