Visible light induced photocatalytic reduction of Cr(VI) over polymer-sensitized TiO2 and its synergism with phenol oxidation

In this study, both Cr(VI) reduction and phenol oxidation induced by polymer-sensitized TiO2 were investigated under visible light. Study of the reaction mechanism indicated that poly(fluorene-co-thiophene) (PFT) acted as a semiconductor and was by itself able to reduce Cr(VI) under visible light irradiation. When coupled with TiO2, PFT served not only as the electron donor for Cr(VI) reduction, but also as a sensitizer. Upon irradiation by visible light, electrons in the sensitizing PFT polymer are excited and are transferred to the conduction band of TiO2. PFT-catalyzed reduction of Cr(VI) was significantly promoted by the presence of phenol, and synergism between Cr(VI) reduction and phenol degradation was demonstrated both by analysis of the FT-IR spectrum of PFT/TiO2 and by measuring the effect of repeated use of PFT/TiO2 on its photocatalytic efficiency. The results provide a cost-effective method to remove organic and inorganic pollutants simultaneously in the complex wastewater.

► Visible light induced photocatalytic reduction of Cr(VI) by PFT-sensitized TiO2.
► The photoelectrons in LUMO of PFT played an important role in reducing Cr(VI).
► A synergistic effect between reduction of Cr(VI) and degradation of the phenol.
► Provide a cost-effective method for the treatment of complex wastewater.