Thermal Kinetics of Monocationic and Dicationic Pyrrolidinium-Based Ionic Liquids

This work presents an in-depth kinetic thermal degradation comparison between traditional monocationic and the newly developed dicationic ionic liquid (IL), both coupled with a bromide (Br(−)) anion by using non-isothermal thermogravimetric analysis. Thermal analyses of 1-butyl-1-methylpyrrolidinium bromide [C(4)MPyr][Br] and 1,4-bis(1-methylpyrrolidinium-1-yl)butane dibromide [BisC(4)MPyr][Br(2)] were conducted at a temperature range of 50–650 °C and subjected to various heating rates, which are 5, 10, 15, 20 and 25 °C/min. Thermogravimetric analysis revealed that dicationic IL, [BisC(4)MPyr][Br(2)] is less thermally stable compared to monocationic [C(4)MPyr][Br]. A detailed analysis of kinetic parameters, which are the activation energy (E(a)) and pre-exponential factor (log A), was calculated by using Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO) and Starink. This study revealed that the average E(a) and log A of [BisC(4)MPyr][Br(2)] are lower than [C(4)MPyr][Br], which may be contributed to by its low thermal stability. Conclusively, it proved that the E(a) and log A of ILs are strongly related to the thermal stability of ILs.