Comparison of methods for activating sesame stalk lignin biochar for removing benzo[a]pyrene from sesame oil.

In this study, three activators and two activation methods were employed to activate sesame lignin-based biochar. The biochar samples were comprehensively characterized, their abilities to adsorb benzo[a]pyrene (BaP) from sesame oil were assessed, and the mechanism was analyzed. The results showed that the biochar obtained by one-step activation was more effective in removing BaP from sesame oil than the biochar produced by two-step activation. Among them, the biochar generated by one-step activation with ZnCl2 as the activator had the largest specific surface area (1068.8776 m3/g), and the richest mesoporous structure (0.7891 m3/g); it removed 90.53 % of BaP from sesame oil. BaP was mainly adsorbed by the mesopores of biochar. Mechanistically, pore-filling, π-π conjugations, hydrogen bonding, and n-π interactions were involved. The adsorption was spontaneous and heat-absorbing. In conclusion, the preparation of sesame lignin biochar using one-step activation with ZnCl2 as the activator was found to be the best for removing BaP from sesame oil. This biochar may be an economical adsorbent for the industrial removal of BaP from sesame oil.