Researchers in Korea have proposed an antibacterial filter that can kill microorganisms in the air trapped in the filter with sunlight and visible light from indoor lighting. Senior Researcher Dongyoon Choi of Korea Institute of Industrial Technology and Professor Jaehee Jeong of the Department of Mechanical Engineering at Sejong University developed a filter to sterilize airborne microorganisms using visible light. The study was published in’Nano Letters’.
Indoor lighting kills microorganisms in the air
Microorganisms such as viruses, bacteria and fungi are floating in the air along with fine dust. Previously, antibacterial filters using inorganic antibacterial materials such as silver, copper oxide, and zinc oxide or natural organic antibacterial materials such as chitosan have been introduced. There was a fear that the effect would decrease.
Therefore, the research team wanted to devise a filter that could affect the surrounding microbes on the filter surface. Accordingly, we have manufactured titanium dioxide-organic dye composite nanoparticles that produce active oxygen when exposed to visible light, and improved the surface to have high moisture durability and photochemical sterilization performance.
Titanium dioxide, a representative photocatalyst, reacts with surrounding oxygen and water when absorbing ultraviolet rays to produce active oxygen that can sterilize microorganisms. However, UV rays are limited to use in real life spaces. Accordingly, there was a research on activating a photocatalyst using visible light, but it was regrettable that the process was complicated.
The research team simplified the manufacturing process by dyeing a visible light-reactive organic dye on the hydrophobic surface-modified titanium dioxide nanoparticles, and formed a three-dimensional nanostructure on a filter with a complex fiber structure through a single aerosol method. Through this, it has secured excellent fine dust removal performance and moisture stability at the same time while increasing the active oxygen generation efficiency.
The filter produced by the actual research team is indoor lighting for staphylococcus epidermis (2.9 mW/cm).2) Showed antibacterial activity of 99.9% after 4 hours and 99.98% after 1 hour in sunlight (18~21 mW/cm2). For reference, at this stage, it was confirmed that it has an excellent antibacterial activity of over 99% against various Gram-negative and positive bacteria, but antiviral characterization has not been performed. However, for practical use, research on optimizing the generation of active oxygen in connection with the safety evaluation of the human body according to the concentration of active oxygen and improving the stability of nanoparticle adhesion is required.
This study introduces a highly efficient photochemical antibacterial method using sunlight and indoor lighting in daily life. It is expected to be applied as a more effective mask and air purifier filter material as it is expected to simultaneously remove fine dust, harmful gases and viruses in the air by generating active oxygen using visible light.
The research team plans to continue research to improve photoregeneration and photoreaction performance in order to overcome the limited lifespan due to photolysis of organic dyes and to achieve excellent antibacterial properties even at lower light levels.
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