Investigation of molecular polarity and thermal stability of monoethanolamine based deep eutectic solvents

In this work, sigma profile and sigma potential were generated using COSMOtherm software to examine the molecular polarity of choline chloride with monoethanolamine based deep eutectic solvents at various mole ratios (i.e., 1:2, 1:3, 1:4, 1:5, 1:6 and 1:7). It is used to analyses the interaction between the molecules during extraction process. The result revealed that the selected DES are feasible for use as extracting solvents for polyphenol extraction process. Also, it shows that the prepared DES was hydrophilic in nature and it denotes ability of the amine to act as a base. Then, using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), the similar molar ratio of amine-based DES was synthesized and their thermal stability was described in terms of decomposition temperatures, mass loss and melting temperature. When heating rate increased, the TGA curves of 1:6 and 1:7 DES, temperature shifted to higher direction when compared to other mole ratios of DES. When HBD is increases thermal stability also increases in this case. HBD plays an important role in thermal stability of DES which mainly depends on intermolecular interactions. Similarly, in DSC 1:6 and 1:7 high melting temperature and high enthalpy was observed when compare to other mole ratios. It denotes by increasing the HBD ratio melting temperature also increased due to stronger intermolecular force and stronger interaction between HBA and HBD. In end the synthesized DES was suggested to be used as intermediate for the extraction of polyphenols from agricultural wastes.