Faceted TiO2 photocatalytic degradation of anthraquinone in aquatic solution under solar irradiation

Anthraquinone (AQ), a common oxygenated polycyclic aromatic hydrocarbon (PAH) in the water environment, often occurs with higher concentrations than its parent anthracene as it is the dominant intermediate from anthracene during both wastewater treatment and transformation in natural waters. During the elimination of PAHs and their intermediates, the water matrix often induces positive or negative effects. In this paper, photocatalytic degradation of AQ in the presence of inorganic ions (NO3−, HCO3−, Fe3+) and organic matter (humic acid) was studied with {101} and {010}-TiO2 as sunlight-driven photocatalysts. Meanwhile, the effect of dissolved oxygen (DO) on photocatalytic degradation of AQ was evaluated. The results showed that NO3− had a slight suppressing effect, while HCO3– and Fe3+ promoted the photocatalytic activity due to formation of new oxidizers (CO3− and H2O2). Interestingly, HA could envelope {101}-TiO2 to inhibit photodegradation; however, it had almost no effect on {010}-TiO2 due to the different surface structures and properties. High dissolved oxygen content in water could markedly promote the photodegradation of AQ. This was consistent with the results of scavenging experiments, which demonstrated that O2– and h+ played more important roles than OH did. A small amount of benzene was detected as an intermediate product of AQ by LC-QTOF-MS analysis. Hopefully, this work can contribute to the understanding of the potential of water remediation by faceted photocatalysts. [Display omitted] •The photocatalytic removal of AQ by faceted TiO2 was higher than that by P25.•The addition of HCO3– could reduce OH and form CO3− promoting AQ degradation.•Fe3+ addition promote AQ degradation by forming Fe2+ and H2O2.•O2– and h+ played important roles in photocatalytic degradation of AQ.