Yong Woo Song

High-efficiency particulate air (HEPA) and charcoal filters have been applied to ventilation systems to save energy and reduce pollutants. However, such filters only work for specific types of pollutants, and their performance is not always sustainable. This study compares the pollutant reduction performance of TiO2 photocatalytic filters with HEPA and charcoal filters in mock-up experiments with toluene as the pollutant, changing air volume, and varying ventilation frequencies. The results show that the HEPA filter was ineffective at reducing toluene, and the charcoal filter was found to have the fastest reduction rate until 180 min after the start of the experiment. However, after 180 min when the charcoal filter was saturated, its pollutant reduction performance rapidly declined, resulting in low persistence. Conversely, the TiO2 photocatalytic filter had a lower reduction rate than that of the charcoal filter but had a continuous pollutant reduction performance during 720 min. Comparing the pollutant reduction effect of the TiO2 photocatalyst filter and the charcoal filter with a reduced amount based on the experimental time, the TiO2 photocatalyst filter has a maximum pollutant reduction effect of about seven times and at least about two times. This study confirms that HEPA and charcoal filters reduce gas pollutants, and it was found that combining TiO2 photocatalysts with ventilation devices can improve indoor air quality in apartment buildings.