Lowering polycyclic aromatic hydrocarbon concentrations in vegetable oil deodorizer distillates and enhancing its utilization by graphene composites

Vegetable oil deodorizer distillates (VODDs), which are the main source of natural tocopherol, are easily contaminated by polycyclic aromatic hydrocarbons (PAHs), and pose health threats to human beings. To remove 16 priority-control PAHs in VODD, three graphene (GR) composites, including TiO2-GR, sepiolite-GR and Fe3O4GR, were prepared. PAH concentrations and removal rates were determined using gas chromatography-mass spectrum (GC-MS). Additionally, density functional theory (DFT) calculation was conducted to simulate and illustrate PAH adsorption on GR composites. The results indicated that the highest BaP removal rate was given to TiO2-GR with 90.37 +/- 3.23 % after 2 h in standard solution. The adsorption followed the pseudo-first order kinetic, with the constant of -0.0141. In contrast, 61.62 +/- 7.88 % total PAHs were removed in VODD using TiO2-GR. Moreover, DFT calculation verified that the strongest adsorption effect occurred between TiO2-GR and PAHs, with the adsorption energy of -2.69 eV. Additionally, GR composite morphology would be changed when LPAH concentrations are higher than 30 mu g kg-1. The results also indicated the retention rates tocopherol ranged from 91.91 +/- 1.92 % to 99.22 +/- 0.88 %. This study firstly provides a useful tool for PAH removal in VODDs while retaining tocopherol. Moreover, it will increase the understanding of adsorption process between PAHs and GR composites.