# Characterization and Use of Char Produced from Pyrolysis of Post-Consumer Mixed Plastic Waste
## 3 Results and Discussion
### Effect of the Operating Temperature on the Properties of the Produced Solids  
#### 3.3.1 Elemental Analysis, Thermal Decomposition, Immediate Analysis, HHV and Surface Properties  
Table 4 presents the results of the characterization of the three solid samples obtained from the pyrolysis of the non-recyclable mixed plastics from municipal solid waste at different temperatures. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Temperature** & & **450 \({}^{\circ}\)C** & **500 \({}^{\circ}\)C** & **550 \({}^{\circ}\)C** \\ \hline \multirow{6}{*}{Elemental Analysis} & \% C & 55.24 & 34.33 & 17.82 \\ \cline{2-5}  & \% H & 5.74 & 1.46 & 0.55 \\ \cline{2-5}  & \% N & 0.46 & 0.40 & 0.24 \\ \cline{2-5}  & \% S & 0.00 & 0.00 & 0.00 \\ \cline{2-5}  & \% O (by difference) & 3.31 & 9.45 & 12.95 \\ \hline \multirow{6}{*}{Immediate or Proximate Analysis} & Moisture, \% & 0.61 & 1.02 & 0.84 \\ \cline{2-5}  & Volatile, \% & 51.00 & 31.22 & 24.90 \\ \cline{2-5}  & Fixed carbon, \% & 13.35 & 13.95 & 6.40 \\ \cline{2-5}  & Ash, \% & 35.04 & 53.81 & 67.87 \\ \hline \multirow{2}{*}{HHV, MJ/kg} & & 23.94 & 10.70 & 3.69 \\ \cline{2-5}  & Specific area, m\({}^{2}\)/g & 0.26 & 7.61 & 67.11 \\ \cline{2-5}  & Pore volume, cm\({}^{3}\)/g & 0.0011 & 0.0165 & 0.0403 \\ \cline{2-5}  & Pore size, Å & 166.76 & 87.04 & 60.09 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Elemental analysis, immediate analysis, HHV and surface properties of the solids obtained by pyrolysis of the non-recyclable mixed plastics from municipal solid waste at different temperatures. The sum of C, H, N and O is relatively low, since the samples present a high content of inorganic compounds (ash content) as evidenced in the immediate analysis. In addition, the carbon, hydrogen and nitrogen content decreases with increasing pyrolysis temperature. The decrease in carbon can be attributed to the transformation of carbonaceous materials into CH\({}_{4}\), CO\({}_{2}\), CO and other aromatic gases or compounds, favored by the increase in temperature. Similarly, the increased release of volatile matter with increasing pyrolysis temperature causes the loss of functional group, which explains the decrease in hydrogen and nitrogen content [27]. The research performed by [PERSON] et al. [45] revealed a similar trend. The C content decreased with increasing pyrolysis temperature from 400 \({}^{\circ}\)C (55.13%) to 700 \({}^{\circ}\)C (49.91%), as the H content (4.33-0.78%) and the N content (1.02-0.93%). The same tendency was presented by the study of [PERSON] et al. [40] since both the C and the H content of the solid product obtained from pyrolysis at 450 \({}^{\circ}\)C and 650 \({}^{\circ}\)C decreased with increasing temperature (from 87.6 to 84.3% and from 6.3 to 1.6% respectively), while the O content increased from 0.6 to 2% in the same temperature range. [PERSON] et al. [19] provided an elemental analysis very similar to the present work, with a C content of 42.65%, H content of 3.06% and N content of 0.43%. Similar results were also reported by [PERSON] et al. [5], where the film-rich sample pyrolyzed at 500 \({}^{\circ}\)C yields carbonaceous solids with a carbon, hydrogen and nitrogen content of 48%, 1.9% and 0.9%, respectively. In addition, [PERSON] et al. [30] found that the carbon content of solid products obtained from pyrolysis of PVC, PE and PET plastic waste decreased with increasing temperature. However, [PERSON] et al. [10] provided different results, as the solids resulting from the pyrolysis of different mixtures of PVC, PET and PE at different temperatures had a higher carbon content (ranging from 41.3-84.7%), while the nitrogen (0.1-2.78%) and hydrogen content (1.83-5.17%) were similar. Finally, [PERSON] et al. [18] using different mixtures of biomass waste, used tires and plastic waste in different proportions, obtained a solid product from pyrolysis at 420 \({}^{\circ}\)C with a high carbon content (around 80%), while the hydrogen (5-7%) and nitrogen (0.5-1%) contents were similar.