Biochar derived from chitin by ultrasonic and calcination for efficient adsorption removal of benzo(a)pyrene from fragrant rapeseed oil: Characterization, kinetics and mechanism

Biochar derived from chitin by ultrasonic and calcination (BC1) could efficiently remove benzo(a)pyrene from fragrant rapeseed oil in the pre-experiment, while the underlying mechanism was unknown. Therefore, the characteristics of BC1 and the adsorption kinetics, isotherms and thermodynamics of BC1 for benzo(a)pyrene (BaP) from fragrant rapeseed oil were analyzed. The results showed that the removal efficiency of BaP by BC1 was 7.33 times higher than that by chitin, with an adsorption capacity of 105.37 μg/g. The synergistic effect of ultrasonic and calcination changed the appearance and functional groups, increased the surface area of chitin. The adsorption of BaP onto BC1 involved a mechanism initiated by the mesoporous structure of BC1. During this process, BC1 captured BaP by filling the pores and combining specific intermolecular forces including hydrogen bonds and π-π interactions caused by surface functional groups on BC1. Additionally, BC1 not only effectively removed BaP, but it most retained nutritional components and flavor substances in oil. • Biochar (BC1) derived from chitin showed promising adsorption capacity of BaP. • Ultrasonic and calcination had a synergistic effect on removal of BC1 for BaP from oil. • Compared with chitin, the removal efficiency of BaP by BC1 was increased by 7.33 times. • Strong π-π interaction of BC1 contributed to the high adsorption capacity for BaP. • BC1 had little impact on the quality of fragrant rapeseed oil.