Enhancement of water soluble PDI-NapSO3H on the photocatalytic performance of Fe-TiO2 under visible light

In this paper, we successfully constructed two composite photocatalysts TiO2@PDI-NapSO3H and Fe-TiO2@PDI-NapSO3H by utilizing water-soluble PDI derivatives to bond with TiO2 or iron-doped TiO2. Their photocatalytic performance to degrade phenol and diclofenac sodium (DCF) under visible light were investigated. The results show that PDI-NapSO3H can effectively improve the optical absorption properties of TiO2. Furthermore, the oxygen vacancy produced by doping of Fe in TiO2 prevents the recombination of photogenerated carriers effectively. The larger conjugate plane of PDI-NapSO3H provides a convenient channel for the migration and separation of photogenerated carriers. Thus almost 99 % of phenol or DCF can be degraded by Fe-TiO2@PDI-NapSO3H within 90 or 120 min, respectively. However, the photocatalytic activity of Fe-TiO2@PDI-NapSO3H is better. The rate of phenol degradation is much higher than that of TiO2@PDI-NapSO3H. Further, through the photoelectric response characteristic analysis, radical trapping experiment and EPR test, the effects mechanism of the energy band structure, photogenerated carrier separation efficiency on the photocatalytic performance of Fe-TiO2@PDI-NapSO3H were discussed. In addition, the possible degradation pathways of DCF and the reasons for the obvious reduction of environmental toxicity after photocatalytic degradation were proposed.