Degradative and disinfective properties of carbon-doped anatase–rutile TiO2 mixtures under visible light irradiation

Carbon-doping of TiO2 was performed to improve the visible light response and photocatalytic activity of this catalyst. In this work, the high temperature annealing of TiC was studied and the anatase–rutile doped TiO2 mixtures created were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible light absorption spectrophotometry (UV–Vis). It was found that the TiC fully reacts at 400 °C. Transformation of the anatase to rutile phase was observed since the latter form is more heat stable. XPS analysis revealed that the carbon in the sample was present as carbonate species. The UV–Vis spectrum of the doped powders were red shifted compared to P25 TiO2, and a band gap narrowing of 0.2 eV was observed. The photocatalytic activity of the powders was quantified by the degradation of methylene blue under visible light irradiation. Langmuir–Hinshelwood kinetics were applied, and the maximum pseudo-first order degradation rate observed was 0.015 min−1 for the powder annealed at 400 °C for 8 h. Disinfection of Escherichia coli K12 was performed using the catalyst in an immobilized configuration under visible light, and up to 80% inactivation was observed, compared to negligible inactivation with P25. The modified Hom disinfection kinetic model was used to describe the data.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (78 K)Download as PowerPoint slideHighlights► Carbon-doped anatase–rutile TiO2 mixtures prepared by the oxidative annealing of TiC. ► Band gap narrowing of 0.2 eV observed. ► Photocatalytic activity of prepared powders tested under visible light for degradation of methylene blue. ► A maximum kinetic constant of 0.015 min−1 observed for powder annealed at 400 °C for 8 h. ► Carbon-doped powder was also able to inactivate up to 80% of Escherichia coli K12 in 30 min.