Inactivation of airborne viruses using vacuum ultraviolet photocatalysis for a flow-through indoor air purifier with short irradiation time

Abstract

Many ultraviolet (UV)-based disinfection methods have been developed; however, these methods usually use the recirculating mode or need long irradiation periods due to its low photon energy. Vacuum UV (VUV) was recently found to be a promising light source, despite its ozone generation. In this study, we investigated photocatalysis reactions by VUV with short irradiation times (0.004-0.125s) for simultaneously inactivating airborne MS2 viruses and degrading the generated ozone toward a flow-through air disinfection system with high flow-rates. We developed three effective shapes for the catalyst frame: 2mm and 5mm pleated, and spiral-type Pd-TiO 2 catalysts. The 2mm pleated Pd-TiO 2 /VUV photocatalyst exhibited the highest activity ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 for simultaneous MS2 inactivation and ozone degradation, and the catalytic activity was effective regardless of relative humidity. Considering the gas phase and catalyst surface effects, and the natural inactivation of VUV-irradiated but live MS2 viruses, the 2mm pleated PdTiO 2 /VUV and succeeding UV photocatalysis showed more than 90% in the overall inactivation efficiency with residual ozone of 35ppb at an irradiation time of 0.009s (flow-rate: 33 l/min). In contrast, most UV-based purifiers take longer times for disinfection. This system has the potential for an alternative to conventional UV-based air purifiers.

Inactivation of airborne bacteria using different UV sources: Performance modeling, energy utilization, and endotoxin degradation

“…Inactivation performance under other UV wavelengths has also been explored. Kim and Jang (2018), for example, investigated several photocatalytic reactions by UVD (185 nm) with short irradiation times to inactivate airborne MS2 viruses. Araud et al (Araud et al, 2018) also investigated the inactivation mechanisms of viruses via solar UVA and visible light.…”

UVC LED Irradiation Effectively Inactivates Aerosolized Viruses, Bacteria, and Fungi in a Chamber-Type Air Disinfection System

“…indoor air disinfection and development of air purification systems to control pathogenic microorganisms, including viruses, bacteria, and fungi (10). In order to ensure microbial safety of air, many studies utilizing UV irradiation have been performed (11)(12)(13)(14). The Centers for Disease Control and Prevention recommended UV germicidal irradiation (UVGI) as a supplementary process in order to prevent transmission of bacteria causing tuberculosis (15).…”

Ultraviolet-C and other methods of decontamination of filtering facepiece N-95 respirators during the COVID-19 pandemic

“…10 Studies have found that the disinfection time required to inactivate bacteriophage MS2 is much lower with light sources emitting UVC and ozone combined than with UVC alone. 12 These systems are limited due to the restrictions related to ozone emission and the toxic effects of ozone on human health. In addition, due to the concerns of mercury pollution, the United Nations Environment Programme (UNEP) convened in 2013 to propose a ban on the export and import of mercury-containing lamps and have them be replaced by UV light emitting diode (UV-LED) light sources; 13 however, countries can still manufacture mercurybased products for their own use.…”