Effect of various carbon supports for TiO2 and N-doped TiO2 photocatalysts for inactivation of Escherichia coli in water under UV–visible light

Abstract

This study evaluates the effectiveness of various carbon nanostructures carbon glassy spheres (CGS), carbon nanopowder (CNP), and activated carbon (AC) as supports for TiO₂ and N-TiO₂ photocatalysts in the inactivation of Escherichia coli (E. coli) in water. The photocatalysts were synthesized using a sol-gel method. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses confirmed the presence of anatase-phase TiO₂ on the carbon supports, with the synthesized TiO₂ nanoparticles exhibiting particle sizes below 10 nm. Fourier transform infrared (FTIR) spectroscopy identified metal‑oxygen bonds and surface hydroxyl groups on the photocatalyst surface, while X-ray photoelectron spectroscopy (XPS) confirmed the Ti⁴⁺ oxidation state and nitrogen incorporation in nitrogen-doped TiO₂ (N-TiO₂) samples. The photocatalytic performance of these materials was investigated for E. coli inactivation under both UV and UV–visible light irradiation. Results demonstrated that carbon-supported TiO₂ and N-TiO₂ nanocomposites exhibited significantly enhanced photocatalytic activity compared to their unsupported counterparts. Superior photocatalytic performance was observed under UV–visible light compared to UV light. Among the three carbon-supported systems, TiO₂ and N-TiO₂ nanocomposites deposited on CGS achieved the highest photocatalytic activity. The enhanced performance was attributed to the morphology and particle size of the carbon supports, which played critical roles in optimizing photocatalytic inactivation of E. coli in water.