The studies of kinetic and atmospheric reaction mechanisms of pyrene in the presence of OH radicals

Pyrene (Py) is a carcinogenic, colorless, solid polycyclic aromatic hydrocarbon (PAHs) which is the most plenteous hydrocarbon in the contaminated urban atmosphere and less volatile. For losing of Py from the environment, the initial reaction of pyrene by hyrdroxyl radical to form hydroxypyrene is the most important atmospheric reaction. The possible reaction mechanism explained by density functional theory (DFT) calculations. Calculations of reaction pathways and kinetics show that the main products are produced via OH-addition as well as the H-abstraction pathways. RRKM (Rice Ramsperger–Kassel–Marcus) theory was used to calculate the kinetic parameters such as rate constants for the beginning steps of Py with OH radicals. The atmospheric lifetime of gas-phase reactions between Py and OH radicals is evaluated about 5.5 days, according to the calculated k_overall (overall rate constant) of 9.54×10−13 cm3 molecule−1 s−1 at T=298 K and P=1 atm. The accessible experimental information show that we obtained the good results.