Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

The present work attempts to measure the solid-liquid equilibrium (SLE) of glucose in three novel low cost deep eutectic solvents (DES) namely tetrabutylammonium bromide [TBAB]-Imidazole, [TBAB]-ethylene glycol, and [TBAB]-glycerol over the temperature range 299.15 to 353.15 K. The [TBAB]-Imidazole DES gave the highest solubility among all the DES. The experimental solubility data was correlated with the Apelblat empirical equation along with regression using local composition models namely NRTL and UNIQUAC models. The thermodynamic functions of dissolution such as enthalpy , Gibbs energy and entropy of dissolution were also calculated from the modified van't Hoff equation. The dissolution functions gave positive values for all the studied systems indicating that the process is endothermic in nature while being non-spontaneous and entropically favourable. In addition, classical Molecular Dynamic (MD) simulations were performed to disclose the glucose-DES interactions. From MD simulations, the anion and hydrogen bond donor (HBD) molecules is seen to overall dominate the dissolution of glucose. From the MD simulations, the anion of hydrogen bond acceptor (HBA) and the hydrogen bond donor (HBD) molecules are primarily responsible for the dissolution of glucose. The isomerization of glucose to fructose in [TBAB]-Imidazolium DES was observed for temperatures above 313.15 K, which resulted in a lower concentration of glucose at higher temperatures.