## 3 Results and Discussion
### Chlorine Content  
Chlorine content is one of the major considerations for the use of wastes as a feedstock for energy production. In this study, the chlorine content of the waste at different extents of torrefraction was measured, and the results are shown below in Figure 2a. The term \"CE material\" represents both  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \(a_{1}\) & 0.39 & \(a_{2}\) & 0.61 \\ \hline \(A_{1}^{*}\) & \(2.81\times 10^{7}\) & \(A_{2}^{*}\) & \(7.58\times 10^{5}\) \\ \hline \(T_{a_{1}}\) & \(1.53\times 10^{4}\) & \(T_{a_{2}}\) & \(1.55\times 10^{4}\) \\ \hline \hline \end{tabLC and HC materials since they have similar behavior for chlorine removal efficiency. The release of chlorine started at \(\sim\)340 \({}^{\circ}\)C, which also aligned with the findings of the mass loss behavior in Section 3.1 since the PVC would release chlorine in the form of hydrochloric acid (HCl) during the torrefaction process [32]. The results showed chlorine reaching an asymptotic value at \(\sim\)80% removal efficiency after 20 min of torrefaction at 400 \({}^{\circ}\)C.  
The previous study showed that the chlorine removal efficiency through torrefaction of PVC would increase as the residence time increased, eventually reaching 100% [24]. However, we noticed that the chlorine removal efficiency of the waste material did not reach 100%, which contradicted the previous results if PVC were the only source of chlorine in the waste. Since the chlorine removal efficiency reached an asymptotic value of \(\sim\)80%, it indicated that all the chlorine from PVC was removed, while the remaining 20% was from an unknown source. The organic chlorine reduction efficiency of CE material through torrefaction was calculated by normalizing the results to its peak value and denoted as organic chlorine removal efficiency. The de-chlorination reaction of chlorine from PVC was assumed to be the first-order reaction, and the organic chlorine removal efficiency was determined by the following equation:  
\[\alpha=1-A_{3}^{*}e^{-\frac{T_{a_{3}}}{T(t)}}. \tag{8}\]  
where \(A_{3}^{*}=1.11\times 10^{9}\) and \(T_{a_{3}}=1.51\times 10^{4}\). The results are shown in Figure 2b, denoted as correlation. To compare the chlorine removal behavior of PVC to the solid waste, torrefied PVC samples at 400 \({}^{\circ}\)C  
Figure 1: Mass loss and temperature transient vs. time. Figure 2: (a) Chlorine removal efficiency (from waste) and temperature vs. time; (b) organic chlorine removal efficiency from waste and from PVC vs. time. with different times were also characterized. Figure 2b also presents the results of organic chlorine removal efficiency from waste and from PVC vs. time, showing that the chlorine release from PVC was not affected by the composition difference. This indicated that chlorine removal from PVC and waste materials, containing PVC, during torrefraction depended on temperature and residence time, not on the waste composition. It also showed that the chlorine removal behavior was independent of the initial chlorine levels and that removal of chlorine was not affected by the presence of other waste components in the surrounding during the process. It was also essential to identify the sources of the remaining 20% of chlorine. [PERSON] et al., 2010 studied the existence of inorganic chlorine in the waste that was found to release in the temperature range of 700 \({}^{\circ}\)C to 1000 \({}^{\circ}\)C using a thermal treatment. According to [PERSON] et al., 2018, alkali chlorides (salt, e.g., KCl, NaCl) were the main sources of the inorganic chlorine in the waste [33]. The method of measuring the chlorine content in the current study was by analyzing the HCl in gaseous form after the combustion of the sample with the combustion temperature of the waste over 850 \({}^{\circ}\)C [34].