Thermal degradation mechanism of the 1,2,3-trichlorobenzene as PCDD/Fs precursor by waste polyurethane

Polyurethane (PU) is a widely used polymeric material that can be valorized through thermal treatment, utilizing its calorific value while reducing waste. However, the thermal processing of waste polyurethane (WPU) can generate secondary pollutants such as NH 3 and HCN. Previous studies have shown that the co-treatment of municipal solid waste with WPU can inhibit polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) formation. Therefore, this study focused on 1,2,3-trichlorobenzene (1,2,3-TCB), a known precursor of PCDD/Fs, to preliminarily investigate its degradation efficiency and mechanism during the combustion of WPU. Experimental results indicated that the hydrodechlorination rate (HDR) of 1,2,3-TCB was significantly enhanced at temperatures exceeding approximately 450 °C, reaching 3.5 times that of the control group. This trend is consistent with previous findings, and such behavior may be attributed to the nitrogenous species released from WPU. With a further increase in temperature, the total degradation rate (TDR) of 1,2,3-TCB reached a maximum of 70% in the 500–550 °C range. Compared to traditional methods relying on external chemical inhibitors, this study utilizes the inherent inhibitory effects of waste polyurethane, offering a sustainable waste-treating-waste strategy for the degradation of persistent organic pollutants. Finally, the degradation mechanism of 1,2,3-TCB was elucidated. This study provides a novel approach for reducing the emissions of PCDD/Fs during the co-combustion of municipal solid waste.