Photocatalytic remediation of fluoranthene contaminated soil by eco-friendly GQDs/TiO2/α-FeOOH composite photocatalyst: Efficiency, influence factors, mechanism, and toxicity analysis

Polycyclic aromatic hydrocarbons (PAHs), as a persistent organic pollutant, have adverse effects on soil environment and human health. In this study, a new type of iron-based material graphene quantum dots (GQDs)/ TiO2/alpha-FeOOH was used to construct a photocatalytic system to achieve effective degradation of fluoranthene in soil. The hydrothermal method and sol-gel method were used to synthesize GQDs/TiO2/alpha-FeOOH composite photocatalyst, which exhibited enhanced photocatalytic activity by promoting charge transfer, increasing specific surface area, and broadening light absorption range. The degradation ratio of fluoranthene in soil suspension by GQDs/TiO2/alpha-FeOOH was 67.37 % under the condition of 24 h of simulated sunlight irradiation, water/soil ratio of 10:1, and catalyst dosage of 50 mg/g. center dot O2- and h+ played the major roles in degradation process, and the catalytic mechanism was proposed. The degradation products and degradation pathway of fluoranthene were analyzed by GC-MS detection and DFT calculation, and the toxicity of degradation products was predicted by simulation calculation. The effect of remedial soil on seed germination was investigated through germination test of tomato seeds, and results showed that the productivity of fluoranthene contaminated soil was recovered in a certain extent.