Photocatalytic treatment of volatile organic compounds emitted from mosquito repel incense burning

Abstract

Mosquito-repellent incense (MRI) is a widely used product in the household. Although the quality of MRI has been strictly managed, it still has certain health effects in practical use. This study investigated the level of volatile organic compounds (VOCs) in MRI smoke and its removal ability by photocatalysis. An online survey was conducted using Google form to select three typical types of MRI which are the most popular use in Vietnam (i.e., MOSFLY, RAID, and JUMBO VAPE) as well as their use level and condition. These types of MRIs were then burnt in a normal room for 8 h to determine the level of air pollution emission. Results from room test show that the tVOCs concentration emitted from one of the MRIs was as high as 1621 ppb, which was the highest pollution level among the three MRIs tested. This type of MRI was then employed as VOCs pollutant source for testing the treatment ability of a photocatalytic equipment in a closed chamber. The experimental treatment of emitted VOCs by the photocatalytic treatment equipment showed that titania nanotubes (TNTs) modified with metal salt and heat treatment achieved high removal efficiency. It has reached indoor air standards of ≤ 490 ppb after 180 min of treatment with an input concentration of about 1,600 ppb. By changing the conditions of TNTs modification and operation conditions, the highest treatment efficiency was achieved with 2 g of zinc doped TNTs at a Zn/Ti molar ratio of 0.5%, calcined at 500 oC, in which the treatment to meet the standard reached the shortest treatment time. The results in this study indicate that burning MRI could cause indoor air pollution that may affect human health and photocatalysis is a potential technology for treating VOCs from indoor MRI burning.