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.