# Characterization and Use of Char Produced from Pyrolysis of Post-Consumer Mixed Plastic Waste
## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Analysis** & & **PP** & **PS-HIPS** & **PS-EPS** & **Film** \\ \hline \multirow{6}{*}{Elemental Analysis} & \% C & 82.92 & 66.47 & 91.69 & 77.61 \\ \cline{2-6}  & \% H & 14.47 & 7.63 & 8.28 & 11.91 \\ \cline{2-6}  & \% N & 0.16 & 0.14 & 0.11 & 0.10 \\ \cline{2-6}  & \% S & 0.00 & 0.00 & 0.00 & 0.00 \\ \cline{2-6}  & \% O (by & & & & \\ difference) & 1.75 & 17.84 & 0.00 & 10.38 \\ \hline \multirow{6}{*}{Immediate or Proximate Analysis} & Moisture, \% & 0.00 & 1.80 & 0.00 & 1.00 \\ \cline{2-6}  & Volatile, \% & 99.3 & 88.9 & 99.8 & 95.5 \\ \cline{1-1} \cline{2-6}  & Fixed carbon, \% & 0.00 & 1.70 & 0.10 & 2.40 \\ \cline{1-1} \cline{2-6}  & Ash, \% & 0.70 & 7.60 & 0.10 & 1.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Results of immediate and elemental analysis contained in the non-recyclable mixed plastics bales from municipal solid waste. Table 3 shows that operating temperature has a great influence on the product yields. Solid product yield has clear tendency to decrease as the pyrolysis temperature increases, except in the case of PP where the yield decreases a lot when temperature increase from 450 to 500 \({}^{\circ}\)C and increase slightly when temperature change from 500 to 550 \({}^{\circ}\)C. The highest yield to solid product obtained is from the pyrolysis of film at lower temperature (450 \({}^{\circ}\)C), reaching almost 14%, followed by the value obtained with high impact polystyrene (PS-HIPS), which exceeds 10% at a temperature of 450 \({}^{\circ}\)C. This is due to the composition of the material, as the PS-HIPS were pyrolyzed together with the wrapping paper and the cellulose in the paper improves the yield of the solid product. With the mixture simulating the real proportions, a maximum solid yield of 4% is achieved at 450 \({}^{\circ}\)C, so it is clear that the solid product would be the minority product of pyrolysis, which could be considered as a by-product based on an industrial application. Regarding liquid fraction, in general, the liquid yield increased with temperature, for example, the liquid yield increased from 27.53% at 450 \({}^{\circ}\)C to 44.25% at 550 \({}^{\circ}\)C for the plastic waste mixture. The main reason for the increase in liquid yield and decrease in solid yield with temperature is that the volatilization reactions are favors by increasing temperature [44]. Finally, a maximum gaseous product yield of 67.91% was obtained at a pyrolysis temperature of 450 \({}^{\circ}\)C in the pyrolysis of plastic waste mixture, which decreased with rising temperature. When temperature increases, the pyrolysis vapor was converted to lower molecular weight organic products with lower molecular weight or other non-condensable gases. However, our results showed significant decrease in the gas yield as the temperature was increased. Perhaps a deficient recuperation of liquid product can occur and poor estimations of gas product are provided since gas yield was calculated by difference as it was indicated in Equation (11). Comparing these results with those found in the literature, there is a great similarity with the study carried out by [PERSON] et al. [45] using a fixed-bed reactor with a heating rate of 10 K/min in a temperature range between 400 and 700 \({}^{\circ}\)C. These authors determined that the yield of the different products depends directly on the temperature. Thus, they observe a decrease in the yield of solid product from 49.8-32.3% as temperature increases, while the yield of liquid product increases from 30-50%, and the yield of gaseous product is practically not affected by temperature. Along the same lines is the study by [PERSON] et al. [37]. [PERSON] et al. [11] studied the pyrolysis of a mixture of waste consisting of PS, PP, PE