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Projeto de investigação
Valleytronics Excitons Qubits
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Estimating the melting temperatures of type V deep eutectic solvents
Publication . Teixeira, Gabriel; Abranches, Dinis O.; Ferreira, Olga; Coutinho, João A.P.
The recently proposed category of type V deep
eutectic solvents (DESs), composed only of non-ionic species, has
attracted great interest in the literature. However, despite their
importance in solvent design, measuring the solid−liquid equilibrium
(SLE) diagrams of all possible type V DES precursor
combinations is unfeasible. Therefore, a reliable computational tool
must be found to estimate SLE phase diagrams and, thus, the
melting points of type V DESs. In this work, a total of 134 different
binary eutectic systems (1744 datapoints) were gathered from the
literature, and the calculation capabilities and accuracy of three
different models COSMO-RS, UNIFAC of Dortmund, and Group
and Group-Interaction Contribution method (GGIC) were
evaluated. UNIFAC and COSMO-RS were, by far, the best
performing models, with average absolute deviations (AADs) of, respectively, 6.9 K for 94 systems and 7.4 K for 133 systems.
Due to a lack of group interaction parameters, UNIFAC could only describe 94 systems, a severe disadvantage over COSMO-RS.
Moreover, despite being able to describe all 134 systems, the GGIC model resulted in an AAD of 37 K. Finally, the effect of using the
different parametrizations or multiple conformers in COSMO-RS predictions was also evaluated, and the validity of neglecting heat
capacity terms when performing SLE calculations was verified.
Polyol-based deep eutectic solvents: betaine versus choline chloride
Publication . Teixeira, Gabriel; Abranches, Dinis O.; Yu, Gangqiang; Held, Christoph; Santos, Luís M. N. B. F.; Ferreira, Olga; Coutinho, João A. P.
This work investigates the potential of betaine as a substitute for choline chloride in the formation of polyol-based DES. The solid-liquid equilibrium (SLE) phase diagrams of binary mixtures of betaine with one polyol (ethylene glycol, 1,3-propanediol, glycerol, meso-erythritol, xylitol, or sorbitol) were studied across the entire composition range. Experimental measurements of the phase diagrams were limited by the thermal degradation of betaine and by the boiling points or high viscosities of some polyols. Overall, betaine exhibited negative deviations from ideality, while most polyols displayed near-ideal behaviour. COSMO-RS, a thermodynamic model, satisfactorily predicts these deviations from ideality and the observed phase behaviour. Mixtures of betaine and polyols yielded a narrower liquid-phase window for room-temperature applications than the corresponding choline chloride systems. The cross-association of betaine with polyols is more favourable than its self-association, and stronger interactions between the polyols and betaine than with choline chloride are expected, leading to more negative deviations; thus, the smaller melting temperature depression must result from a higher enthalpy of fusion of betaine than that of choline chloride.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
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OE
Número da atribuição
SFRH/BD/151114/2021