Examinando por Autor "Gonzalez, Miguel A."

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Influence of the carboxylate anion on the CO2 absorption mechanism using based-imidazolium ionic liquid
(Elsevier, 2025-01) Murillo-Criado; Aguilar-Galindo, Fernando; Serrano, Isabel; Gonzalez, Miguel A.; Tojo, Emilia; Suárez, Inmaculada; Coto, Baudillo; Tenorio, Maria Jose
The reduction of atmospheric carbon dioxide (CO₂) levels is contingent upon the implementation of strategies such as the curtailment of fossil fuel usage, the adoption of renewable energy sources, and the utilization of CO₂ capture and utilization technologies. Although direct air capture (DAC) presents a significant opportunity for global mitigation, industrial efforts have primarily concentrated on pre-combustion, oxyfuel, and post-combustion capture methods to enhance environmental sustainability. Nevertheless, the economic viability of CO₂ reuse remains a significant concern, and the development of innovative solutions is imperative. In this study, the influence of the carboxylate anion on CO2 absorption process using imidazolium-derived ionic liquids (ILs) is compared. 1-Butyl-3-methylimidazolium formate ([BMIm][HCOO]), 1-butyl-3-methylimidazolium acetate ([BMIm][OAc]), and 1-butyl-3-methylimidazolium propionate ([BMIm][C3H5OO]) have been analyzed. The efficacy of the capture process was assessed by quantifying the formation of an IL-CO₂ adduct using nuclear magnetic resonance (NMR) and attenuated total reflection infrared spectroscopy (ATR-IR). Furthermore, this work studies, using Density Functional Theory (DFT) and COSMO modelling, the difference in the spontaneity of the proton transfer from the cation [BMIm]+ to the carboxylate anions of the ionic liquids used in CO2 absorption process. Based on experimental and modelling data, [BMIm][OAc] was identified as the optimal IL candidate, presents a CO2 molar fraction absorbed at 30 °C and 1 bar of 0.203, compared to 0.083 for [BMIm][HCOO] and 0.190 for [BMIm][C3H5OO]. Moreover, theoretical simulations support these results with the calculation of the acid deprotonation equilibrium constants with the highest value being obtained for [BMIm][OAc]
Membrane-Ion Interactions Modify the Lipid Flip-Flop Dynamics of Biological Membranes: A Molecular Dynamics Study
(American Chemical Society, 2020-06-10) Gonzalez, Miguel A.; Bresme, Fernando
La distribución asimétrica de lípidos en la membrana celular se mantiene gracias a transportadores proteicos y, en su ausencia, mediante el flip-flop espontáneo, un proceso que implica la formación de poros transitorios en la membrana. Este fenómeno es clave, ya que la composición lipídica de la membrana regula el metabolismo celular al modular la función de proteínas transmembrana. Las membranas están en contacto directo con soluciones acuosas que contienen iones, los cuales interactúan con los grupos cabeza de los lípidos o atraviesan la membrana a través de canales. Sin embargo, el efecto de los iones sobre las tasas de flip-flop no estaba claro. Este estudio demuestra que la valencia de los cationes influye significativamente en las tasas de flip-flop: con cationes monovalentes (Na⁺, K⁺), el proceso ocurre en minutos; con cationes divalentes (Mg²⁺, Ca²⁺), en horas; y con cationes trivalentes (Yb³⁺), se ralentiza drásticamente, llegando a tardar días. Estos hallazgos destacan cómo la interacción entre los iones y la membrana afecta la estabilidad lipídica y podría tener implicaciones importantes para el metabolismo celular y la funcionalidad de las membranas biológicas.