Sulfur hitchhiking on microplastic during dyeing sludge incineration: Simultaneous intensification release of gaseous sulfur and chlorine

Conventional pollutant (organic sulfur) and emerging pollutant (microplastics (MPs)) coexist in dyeing sludge (DS) medium, and their interaction during DS incineration might bring in unexpected secondary pollutions, which is still in a "fog". This study aimed to uncover the interaction between organic sulfur (mercaptan (M) and sulfone (S)) and polyvinyl chloride (PVC) MPs on combustion behavior and gases evolution incorporation of combustion kinetics and density functional theory (DFT) calculation. The presence of PVC advanced the thermal degradation of M and S, while M accelerated the dehydrochlorination and devolatilization of PVC. Contrary to the nature of materials, higher PVC enhanced combustibility and burnout performance of mixtures. The coexistence of PVC and M/S intensified the output of CHSH, SO and HCl, with growth rates reaching 2.18, 2.33, and 1.47 times. The interaction between M/S and PVC promoted combustion progress and intensified CHSH, SO, and HCl output. The combustion kinetic of M/S-PVC mixtures were accurately described by a four-stage model (all R > 0.97). PVC reduced the activation energy (E) of organic sulfur, while M reduced the E value of PVC. Detailly the concurrent presence of SO and HCl lowered the energy barrier for C-H, C-Cl, and C-S bond breakage in residues.