Photodegradation Kinetics of Toluene in Indoor Air at Different Humidities Using UVA, UVC and UVLED Light Sources in the Presence of Silver Titanium Dioxide

Abstract

This study investigated the photo-decomposition kinetics of toluene in indoor air pollution by ultraviolet light using ultraviolet light emitting diodes (UVLEDs) instead of the more traditional ultraviolet lamp emitting at 254 nm (UVC) or 365 nm (UVA). The study was conducted at different humidities (RHs) and energy efficiencies of the lamps. Experiments were conducted over a range of residence times between 20 and 450 min, relative RHs of 0—50% and toluene concentrations between 20 and 350 ppm. Photo-catalytic decomposition of toluene at various initial concentrations and moisture contents were elucidated according to the Langmuir—Hinshelwood model. The reaction kinetics of the three light sources over 0.5 g of silver titanium oxide (Ag/TiO2) are proposed. A comparison of the simulation results with the experimental data was also made, indicating good agreement. The magnitudes of average energy effectiveness (Ee) under various RHs at the same degradation efficiency (η) were in the order of UVLED (6.7 × 10-4 mg · kW-1 · h-1) >UVC (1.1 × 10-4 mg · kW-1 · h-1) >UVA (9 × 10 -5 mg · kW-1 · h-1). The UVLED uses a lot less energy in comparison with traditional UV lamps. Thus, this study shows the feasible and potential use of UVLED for photocatalysis in the indoor environment with the advantage of energy conservation and greater security.