Using heteroatom in nitrogen-mediated pyrolysis to suppressed polycyclic aromatic hydrocarbon derived from cellulose and polyethylene waste

The conversion of waste plastic to biochar is an environmentally friendly and economically feasible approach to handle the current global crisis of plastic pollution. This study investigates the fabrication of biochar from cellulose and polyethylene plastics composites (CLPE) via co-pyrolysis under various temperatures ranging from 300 to 900 °C, focusing on hazard associations of pyrogenic-derived polycyclic aromatic hydrocarbons (PAHs). CLPE900, synthesized at 900 °C under N 2 as a carrier gas, exhibited a higher concentration of PAHs (15,849 ± 315 ng g –1 ) than CLPE700 (2,480 ± 56 ng g –1 ) produced in a CO 2 atmosphere. Further, different heterogeneous atoms including B, N, NB, S, SB, and NS were used as dopants to reduce PAHs formation and improve CLPE co-pyrolysis. Specifically, by combining boron moieties with CLPE potentially suppressed the formation of PAHs, resulting in a 99.7% removal performance. These findings reveal a promising avenue for mitigating the environmental impact of PAHs via heteroatom-assisted thermal chemical processing. • CLPE900 had high PAH content, particularly LPAH naphthalene. • CLPE pyrolysis under CO 2 atmosphere significantly suppressed PAH formation. • B-modified CLPE exhibited the highest PAH removal efficiency among all heteroatoms. • Heteroatom modification effectively removed PAHs in biochar.