New strategy for enhanced degradation of regulated polycyclic aromatic hydrocarbons in coal tar pitch by long chain alkene modification

The presence of toxic polycyclic aromatic hydrocarbons (PAHs) in coal tar pitch (CTP) restricts its sustainable application and poses severe environmental risks. This study developed an alkylation method by using 1-tetradecene to modify CTP, aiming to reduce hazardous compound content while comprehensively evaluating sample toxicity through chemical and biological indicators. The modification achieved 92.73% reduction rate for the 16 priority PAHs regulated by the U.S. Environmental Protection Agency (EPA) in real CTP and decreased PAHs emissions in CTP fumes by 97.47%. In exploratory experiments, the four model PAHs, phenanthrene, anthracene, fluoranthene, and pyrene, were reduced by 99.97%, surpassing all previously reported literature. Comprehensive evaluations using cytotoxicity, toxicity calculations, and ecological indicators confirmed a significant decline in overall toxicity. The study successfully explained the molecular mechanism of the alkylation reaction and clarified why the long-chain alkene prevented cellular carcinogenicity. The study supplied a crucial theoretical foundation for the safe utilization of CTP in road construction. Furthermore, extending this method to waste plastic pyrolysis products established a sustainable framework for resource recycling and waste treatment.