Enhancing the self-cleaning properties of ball-milled TiO₂ nanoparticles: Sustainable utilization of natural rutile and leucoxene from Thailand

This study explores the self-cleaning improvement of natural titanium dioxide (TiO₂) minerals—rutile and leucoxene—sourced from Thailand, using a green ball milling process. High-energy milling was performed for 2–10 h with zirconia balls in ethanol, avoiding the use of hazardous chemicals. X-ray diffraction (XRD) results showed that the crystallite sizes of rutile and leucoxene decreased from 36.7 nm to 15.5 nm and from 45.4 nm to 20.5 nm, respectively. Contact angle tests indicated enhanced hydrophilicity after UV exposure, with values dropping from 30.5° to 23.1°. Surface morphology changes were confirmed by Scanning Electron Microscopy (SEM), and Brunauer–Emmett–Teller (BET) analysis revealed an increase in surface area from 6.6 m²/g to 12.2 m²/g. Photocatalytic activity was assessed using Rhodamine B degradation under Xenon light. The efficiency improved with milling time, reaching 12.8 % for rutile and 0.7 % for leucoxene after 8 h. Although the photocatalytic performance was modest, the overall improvements in surface and structural properties point to a promising, sustainable and low-cost method for developing self-cleaning materials from natural minerals, particularly in contexts where eco-friendliness is prioritized over peak performance, such as when compared to commercial photocatalysts like nano P25, a standard TiO₂ benchmark composed of ∼80 % anatase and ∼20 % rutile. • Ball milling reduced crystallite size and improved self-cleaning of TiO₂ minerals. • Photocatalytic activity increased with longer milling under UV and visible light. • A green, low-cost synthesis route using natural minerals and ethanol was demonstrated.