Degradation and Water-Soluble Particle Conversion of VOC by Photochemical/Photocatalytic Reaction under UV Irradiation —Possibility of Application to Air Washer System —

摘要

Even trace gaseous compounds, such as volatile organic compounds (VOCs), now cause air contamination in cleanroom because of their damage to wafer surface. Air purification system consisting of "Air washer" using water shower and "Chemical filter" is one of the good methods for treatment of fresh air from outdoors and circulation air in cleanroom. However, removal ratio of VOCs by Air washer is very low due to their water-insolubility. In this study, gas-to-particle conversion and water-solubilization of VOCs were performed by photochemical reaction under irradiated condition of short-wavelength UV light (254 nm + 185 nm) with or without TiO2 photocatalyst. Effects of photocatalysis under the short-wavelength UV light were also evaluated from removal ratio of VOCs, their mineralization ratio to CO2, and diameter and composition of particulate decomposition products. Water-soluble dicarboxylic acids were mainly identified in the particulate decomposition products. While, in case of TiO2 addition, the removal ratio of toluene and mineralization ratio to CO2 were enhanced. Finally, we proposed the water collection-UV/photocatalysis process with TiO2 photocatalyst to keep the water in “Air washer” clean.