Investigation on the Characteristics of Tetrabutylammonium Chloride Based Deep Eutectic Solvent Aqueous Solution

Deep eutectic solvents (DES) have attracted more attention due to the excellent performance and environmental protection. In the study and application of DES, the presence of water cannot be ignored. Thus, it is of importance to study the effect of water on DES. In this work, tetrabutylammonium chloride (TBAC) was chosen as the hydrogen bond acceptor (HBA). Decanoic acid (DEC) and octanoic acid (OC) were chosen as the hydrogen bond donor (HBD). Then, two kinds of DES were prepared with the mole ratio of 1:2 for HBA:HBD. The water was added into the sample to form the mixing system. The properties of these DES and their aqueous solutions were analyzed. The thermogravimetric (TG) experiment was conducted to obtain the TG curves for the thermal stability evaluation. The data of density and viscosity for (1 − x)DES–xH₂O (x represents the molar fractions of H₂O) were measured at the temperatures ranging from 303.15 K to 343.15 K. Furthermore, the hard sphere model was introduced for the predictions of viscosity with the average absolute relative deviation for the pure DES and their aqueous solution less than 2.71 % and 7.65 %, respectively. It indicates the fine prediction of these models. Moreover, the excess molar volume, the viscosity deviation and the excess molar Gibbs energy of activation were calculated for the further analysis of the interactions between DES and water.