# Thermogravimetric Study of Refuse Derived Fuel Produced from Municipal Solid Waste of Kazakhstan
## 3 Results and Discussions
### Combustion Kinetics  
Linear plots by FWO, KAS, and Friedman methods for RDF samples were prepared and shown in Supplementary Figure S1a-c. The plots showed good correlations and were used to calculate activation energy at each conversion rate (<0.9). The correlation coefficients of these methods were all above 0.9 for RDF (except \(\alpha\) = 0.6), which suggests that these methods are applicable for defining the activation energy based on the TGA data. The results of an activation energy calculated for RDF are shown in Table 4. Since FWO, KAS and Friedman models produced almost similar results, we used FWO method for analysis of the components of RDF (mixed paper, mixed plastic, and textile). A similar procedure was used for the other samples, and the linear plots and kinetic parameters provided in the Supplementary Materials part as Figures S2-S4 and Tables S1-S3, respectively. The relationship between the calculated activation energy and conversion rate for all samples is shown in Figure 6.  
Figure S1 shows the isoconversional lines of FWO, KAS, and Friedman methods. It can be seen that FWO and KAS plots have good correlation. The activation energy values from Friedman methods are slightly lower than other methods, as noted in Table 4. The activation energy was recorded as 365.27, 375.13, and 331.47 kJ/mol at \(\alpha\) = 0.1 for each model. The slight increase in the activation energy was found at \(\alpha\) = 0.7 in all three methods, which means that there was the energy requirement for the final decomposition step of RDF. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \(\alpha\) & \multicolumn{3}{c}{**FWO**} & \multicolumn{3}{c}{**KAS**} & \multicolumn{3}{c}{**Friedman**} \\ \cline{2-10}  & **A (min\({}^{-1}\))** & **E\({}_{\textbf{a}}\) (k)/mol** & **R\({}^{2}\)** & **A (min\({}^{-1}\))** & **E\({}_{\textbf{a}}\) (k)/mol** & **R\({}^{2}\)** & **A (min\({}^{-1}\))** & **E\({}_{\textbf{a}}\) (k)/mol** & **R\({}^{2}\)** \\ \hline
0.1 & \(1.10\times 10^{35}\) & 365.27 & 1.00 & \(4.88\times 10^{35}\) & 375.13 & 1.00 & \(7.47\times 10^{29}\) & 331.47 & 1.00 \\
0.2 & \(1.55\times 10^{21}\) & 236.04 & 0.98 & \(2.55\times 10^{21}\) & 238.74 & 0.98 & \(7.58\times 10^{17}\) & 215.22 & 0.99 \\
0.3 & \(1.71\times 10^{18}\) & 208.55 & 0.94 & \(2.06\times 10^{18}\) & 209.57 & 0.94 & \(2.41\times 10^{15}\) & 191.04 & 0.95 \\
0.4 & \(8.90\times 10^{16}\) & 197.52 & 0.87 & \(9.17\times 10^{16}\) & 197.74 & 0.85 & \(2.47\times 10^{14}\) & 182.18 & 0.87 \\
0.5 & \(2.66\times 10^{16}\) & 195.28 & 0.69 & \(2.54\times 10^{16}\) & 195.11 & 0.66 & \(1.46\times 10^{14}\) & 182.41 & 0.68 \\
0.6 & \(7.94\times 10^{18}\) & 111.15 & 0.27 & \(2.14\times 10^{8}\) & 106.17 & 0.23 & \(1.61\times 10^{7}\) & 102.72 & 0.25 \\
0.7 & \(4.78\times 10^{15}\) & 203.62 & 0.81 & \(4.06\times 10^{15}\) & 202.83 & 0.80 & \(6.84\times 10^{13}\) & 193.26 & 0.81 \\
0.8 & \(2.69\times 10^{12}\) & 169.23 & 0.67 & \(1.40\times 10^{12}\) & 166.09 & 0.96 & \(6.57\times 10^{10}\) & 159.3 & 0.97 \\
0.9 & \(7.52\times 10^{9}\) & 140.31 & 0.98 & \(2.37\times 10^{9}\) & 135.00 & 0.97 & \(3.69\times 10^{8}\) & 131.11 & 0.98 \\ Mean & \(1.22\times 10^{34}\) & 203 & & \(5.42\times 10^{34}\) & 202.93 & & \(8.30\times 10^{28}\) & 187.63 & \\ SD & \(3.67\times 10^{34}\) & 71.63 & & \(1.63\times 10^{35}\) & 76.16 & & \(2.49\times 10^{29}\) & 63.99 & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Kinetic parameters of RDF fraction by Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Friedman methods.