4.6 Thermo-kinetics parametersKinetic parameters were calculated using the Coats-Redfern method31 was used to calculate the activation energy (Ea) and the pre-exponential factor (A).32 The results are presented in Table 4. The Ea of N0 and N2 were the same, indicating no effect of the BZC/rGO catalyst on the activation energy of NTO. However, the pre-exponential factor of the N2 was increased indicating a slower decomposition of N2 than N0. Both, the pre-exponential factor and activation energy of N1 were decreased indicating the faster decomposition of N1 than pure N0, indicating a good catalytic effect of BZC on the thermal decomposition of NTO than BZC/rGO. The activation energy of A0 for both HTD and LTD steps was increased when BZC/rGO (A2) additive was incorporated in AP, suggesting a negative effect of the additive on the kinetic parameters of AP. In A1, both the activation energy and the pre-exponential factor were in between that of LTD and HTD Ea and A of A0, this could be the result of the merging of the two exothermic peaks of A0 into a single peak in the case of A1 containing BZC additive. Various thermodynamics parameters were evaluated using Eq. (1) to (3).33\(H=E-RT\) (1)\(G=E+RTln\left(\frac{K_{B}T}{A}\right)\) (2)\(S=\frac{H-G}{T}\) (3)
Where, R, T, E, G, H, and S represents the Universal gas constant (kJ mol-1 K-1), temperature (K), activation energy, Gibbs free energy, enthalpy, and entropy, respectively. KB and h represent Boltzmann constant and plank’s constant, respectively. Thermo-kinetic data of the various samples are given in Table 3. N1 has the least value of thermo-kinetic parameters than N0 and N1, suggesting a very good catalytic effect of BZC on the thermal decomposition of NTO. A similar effect of BZC was observed on the thermo-kinetic parameters of AP. Hence, thermo-kinetics parameters also suggest that BZC was indeed a good catalyst than BZC/rGO for the thermal decomposition of both AP and NTO. High energy materials are assumed to undergo various oxidation and reduction reactions during their decomposition. BZC has lower bandgap energy than the BZC/rGO and hence, in BZC electron/hole transfer becomes easy during the decomposition and therefore BZC acts as a better catalyst than BZC/rGO.
Table 4. Kinetic and thermodynamic parameters obtained using Coats-Redfern method.