Abstract In this study, the plant biomass from the phytoremediation was recovered, prepared, and investigated catalytic ability for the α-pinene isomerization. The results show that the Fe_loaded AAL biochar can catalyze the isomerization of a-pinene, with the α-pinene conversion of 90.5 % and the selectivities for monocyclic terpenes (limonene, terpinolene and γ-terpinene) of 57.1 %, bicyclic terpene (camphene) of 24.6 %. Iron in the plant biomass from phytoremediation is considered a decisive factor that heightened the conversion of α-pinene and the yield of isomers. This research has initially opened up a new application for the plant biomass absorbing heavy metal from the phytoremediation stage to resolve contaminants efficiently.