Formation pathways of polychlorinated dibenzofurans (PCDFs) in sediments contaminated with PCBs during the thermal desorption process

► PCDF formation pathways from sediments contaminated with PCBs have been proposed. ► PCBs and PCDDs in sediment were almost completely decomposed by thermal desorption. ► Quantities of PCDFs increased in the effluent gas with decreased chlorine atoms. ► Three formation pathways and dechlorination were responsible for PCDFs formation.