Application of ultraviolet light-emitting diode photocatalysis to remove volatile organic compounds from indoor air.

Photocatalytic oxidation (PCO) is a promising technology for indoor air purification due to low operating cost, potentially long service life, and low maintenance. Ultraviolet light-emitting diode (UVLED) is a new concept in the field of PCO, which has several advantages over conventional UV light sources. Limited research has been conducted using UVLED PCO for air treatment. This study demonstrated the potential application of UVLED for the removal of volatile organic compounds (VOCs; toluene and xylene) from indoor air under different operating conditions including flow rate (25-117 cubic feet per minute [cfm]), types of catalysts (Degussa P25, sol-gel TiO2, nitrogen-doped TiO2, clay TiO2, and Bi2O3), LED intensity, and humidity in a continuous reactor. About 7-32% VOC removal occurred depending on the experimental conditions. The results show that UVLED can activate different types of photocatalysts effectively. This study demonstrates the effectiveness of UVLED in photocatalytic oxidation applied for indoor air cleaning. Several TiO2 catalysts (Degussa P25, sol-gel TiO2, nitrogen-doped TiO2, clay TiO2, and Bi2O3) were used in the reactor to characterize the removal performance of indoor air pollutants, for example, VOCs. This is one of the very few studies that have, to date, examined toluene and xylene removal from indoor air using these catalysts with UVLED in a continuous reactor. The intent is to develop an energy-efficient continuous reaction system to remove VOCs from indoor air. The performance of the system was characterized with respect to air flow rate, humidity, types of catalysts, and light intensity.