Development of a Visible Light-Responsive Titanium Dioxide-Based Multiple Scattering Light System for Water Purification

Water pollution significantly impacts public health, necessitating immediate and effective remediation strategies. Conventional water purification systems are often large, costly, and energy-intensive. Photocatalytic reactions have traditionally been restricted to the ultraviolet (UV) spectrum (wavelengths below 380 nm). This study aims to develop an advanced purification system utilizing a multiple scattering amplification mechanism with visible light-responsive titanium dioxide. We utilized a nonwoven fabric substrate developed by Opes Co., Ltd., embedded with titanium dioxide (TiO2) that exhibits photocatalytic activity under visible light wavelengths up to 570 nm. The TiO2 nanoparticles range in size from 20 to 50 nm. Unlike conventional photocatalysts, this visible light-responsive TiO2 can be activated by commercial LED lighting. To further enhance the photonic efficiency, we incorporated a highly reflective material, MCPET, manufactured by Furukawa Electric, which is known for its superior total and diffuse reflectance properties in the visible spectrum. The integration of the nonwoven fabric with the MCPET reflector results in multiple scattering events, including Rayleigh scattering by the TiO2 nanoparticles, as well as enhanced total and diffuse reflection by the reflector. The primary objectives of this research are to evaluate the purification efficiency facilitated by photonic enhancement and to activate the photocatalytic reaction under visible light. By harnessing visible light-responsive TiO2 and optimizing light distribution through multiple scattering mechanisms, this study seeks to establish a cost-effective and energy-efficient water purification