Impact of inorganic additives and ageing on polycyclic aromatic hydrocarbon emission from polyurethane foam...

The formation of polycyclic aromatic hydrocarbons (PAHs) during polyurethane foam (PUF) combustion poses major environmental and health concerns. Yet, the roles of inorganic additives and thermal ageing in PAH emissions remain poorly understood. This study systematically investigated the influence of inorganic additives (CaCO₃ and CaCl₂, at 5% and 10% w/w) and thermal ageing on PAH emissions across a temperature range of 650-900 °C. Flexible PUFs were synthesized under controlled conditions, subjected to standard ageing protocols, and combusted in an electrically heated tube furnace. The particle-bound PAHs were collected on quartz filters and then quantified by gas chromatography coupled with mass selective detection (GC-MS). Statistical analyses (three-way ANOVA and Tukey's HSD) were performed to evaluate the main and interaction effects of ageing, additive concentration, and combustion temperature. The results demonstrate that temperature is the dominant factor, with PAH emissions rising sharply above 850 °C, particularly in aged foams. Ageing consistently promoted the formation of heavier PAHs, consistent with structural degradation of the polymer facilitating aromatic growth. Inorganic additives exhibited distinct and compound-specific influences on PAH emissions. CaCO₃ had only low, mostly suppressing effects in the case of non-aged foams, while CaCl₂ showed a dual role, promoting PAHs at 750-850 °C but suppressing them at 900 °C. These results highlight the contrasting mechanistic roles of carbonate and chloride additives in controlling aromatic growth pathways. These findings provide mechanistic insights that can inform safer PUF design and guide emission control strategies in waste management.