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

Abstract 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 (NO 3 − , HCO 3 − , Fe 3+ ) and organic matter (humic acid) was studied with {101} and {010}-TiO 2 as sunlight-driven photocatalysts. Meanwhile, the effect of dissolved oxygen (DO) on photocatalytic degradation of AQ was evaluated. The results showed that NO 3 − had a slight suppressing effect, while HCO 3 – and Fe 3+ promoted the photocatalytic activity due to formation of new oxidizers (CO 3 − and H 2 O 2 ). Interestingly, HA could envelope {101}-TiO 2 to inhibit photodegradation; however, it had almost no effect on {010}-TiO 2 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 O 2 – 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.