Fabrication of Water-Based ${\mathrm{TiO}}_2$-Coated Pleated Synthetic Fiber toward Photocatalytic Oxidation of VOCs and CO for Indoor Air Quality Improvement

While titanium dioxide (${\mathrm{TiO}}_2$) is highly regarded as one of the most promising catalysts for air-pollution mitigation, its practical use has been challenging due to structural complexity, process scalability, and high cost of existing fabrication methods. In this study, a facile spray-coating method is employed for fabrication of a ${\mathrm{TiO}}_2$-coated filter, with fibrous structure allowing for satisfactory airflow, sufficient pollutant–catalyst interactions, and reusability. Scanning electron microscopy (SEM) analysis shows that ${\mathrm{TiO}}_2$ nanoparticles were immobilized firmly on the surface of the membrane’s fibers. Energy dispersive X-ray (EDX) analysis reveals a homogeneous layer of ${\mathrm{TiO}}_2$ nanoparticles on the pleated washable synthetic (PWS) fibers. The photocatalytic oxidations of volatile organic compounds (VOCs) and carbon monoxide (CO) are analyzed in both the laboratory and field tests. ${\mathrm{TiO}}_2$-coated PWS filter membrane ($60\times 60\times 5\mathrm{cm}$) shows higher benzene and toluene removal efficiency (approximately 80%–86%) under UV radiation than that in the dark (less than 10%). This result indicates that photocatalytic oxidation on the surface of ${\mathrm{TiO}}_2$-coated PWS filter membrane contributes greatly to benzene and toluene degradation. The corresponding pilot-scale photocatalytic air filtration unit shows ethylene reduction rate of $1.59\pm 0.52{\mathrm{ppm}\min }^{-1}$ in a $45{\mathrm{m}}^3$ postharvest storage room. In a demonstrative elimination of automotive exhaust gases, the ${\mathrm{TiO}}_2$ coated PWS filter membrane shows a 16% decrease in CO generated from a motorcycle. This study shows the potential use of the cost-effective ${\mathrm{TiO}}_2$-coated filter membrane for indoor air quality improvement.