Abstract:

In response to the temperature dependent solubility and dissolution rate of zinc oxide in the choline chloride oxalic acid dihydrate（CC-OA） system，thermogravimetric analysis was used to investigate the effects of zinc oxide concentration w（ZnO），holding time，and temperature on the thermal stability of the CC-OA-ZnO system.The research results indicated that the thermal decomposition process of CC-OA could be divided into three main stages，first of which was the removal of water and the breaking of hydrogen bonds，CC-OA was decomposed back into ChCl and OA.Subsequently，it entered the thermal decomposition stage of OA.The final stage was the thermal decomposition of ChCl.For the CC-OA-ZnO system，its thermal decomposition mechanism could also be divided into three stages，with the second and third stages being the same as CC-OA.In the first stage，the CC-OA-ZnO system need to overcome hydrogen bonding and polymerization.With the increase of w（ZnO），the thermogravimetric （TG） and differential thermogravimetric（DTG） curves of the CC-OA-ZnO system showed a trend of shifting towards high temperatures，indicating that the system had better short-term thermal stability with the increase of w（ZnO）.Within the insulation time range of 0 h to 64 h，a higher w（ZnO） was beneficial for improving the long-term thermal stability of the system，and the final phenomenon of the system did not show significant changes compared to the original sample.

Key words: eutectic solvent, zinc oxide, thermal stability, choline chloride, oxalic acid dehydrate