Phototransformation rate constants of PAHs associated with soot particles

► PAHs on soot were evaluated by a model of coupled photolysis and diffusion. ► Photodegradation rate at the surface, diffusion coefficient, and light penetration path were determined. ► Low MW PAHs were influenced by fast photodegradation and fast diffusion. ► High MW PAHs were controlled either by slow photodegradation and slow diffusion or by diffusion alone. ► Fitted parameters were useful for describing empirical results of photodegradation of PAHs on soot.