Photosensitized degradation of 2,4′,5-trichlorobiphenyl (PCB 31) by dissolved organic matter

► Addition of DOM accelerated the photodegradation of PCB 31 significantly. ► The allochthonous DOM showed higher reactivity in the photolysis of PCB 31. ► The maximum photodegradation rate of PCB 31 was observed in 5 mg/L DOM solutions. ► OH and intra-DOM 1O2 were more important for the photolysis of PCB 31.