Purification of indoor air by non-thermal DBD plasma combined with photocatalysis
Machala Z, Destrieux A, Vazquez T, Lavrikova A,
14th Asian-European International Conference on Plasma Surface Engineering (AEPSE 2025), Phuket, Thailand, November 2-6, p. x (2025)
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Abstrakt: Indoor air contains many harmful contaminants (chemical pollutants, bio-pathogenic aerosols, tobacco smoke, etc.) that can cause respiratory, cardiovascular, and oncological diseases under long-term exposure. Many hospital-acquired infections are also spread through air contaminants. Finding an innovative technology that would efficiently remove all airborne pollutants without producing harmful by-products and with a low energy cost would be a major advance for public health. It would also help to prevent the spread of airborne pathogens such as the recent COVID-19 pandemic. Contrary to traditional filters that just trap the contaminants, the goal of this work is to develop non-thermal plasma DBD technology combined with UV-induced photocatalysis for the removal of volatile organic compounds (VOC) [1], fine and ultrafine particulate matter, and inactivation of aerosol-borne bacteria at high gas flow rates relevant for real indoor settings.
We designed an indoor air decontamination device that combines a DBD and a TiO2 coating activated on-demand by UV-C lamps or UV-A LEDs. The device uses a very short residence time of the pollutant in the reactor: the gas flow rate is high (>120 L/min), and uses a single-pass method. The chemical analysis of the VOC contaminants (formaldehyde) and the gaseous products by the DBD was performed by FTIR absorption spectroscopy. The water aerosol-borne bacteria E. coli and S. aureus were collected after a single-pass on Petri dishes and evaluated by thermostatic cultivation.
Formaldehyde stock solution always contains methanol; hence its removal is associated with methanol decomposition. The formaldehyde removal efficiency depends strongly on the air relative humidity, varying from 30 to 50% at 120 L/min air flow rate in the single pass. Higher humidity is favorable for the decomposition of ozone generated by the DBD, which should be decomposed by the photocatalytic process before exiting the device. The obtained decontaminations of bio-aerosols are very promising: 3.73 log (99.98%) and 3.32 log (99.95%) inactivation of water aerosol-borne E. coli and S. aureus, respectively [2].
In summary, we developed a new device for indoor air purification efficient for chemical (VOC, fine and ultrafine particles) and biological decontamination. It employs combined effects of DBD plasma and UV activated TiO2 photocatalysis. The device can operate at high gas flow rates (>120 L/min). High inactivation of both organic chemical pollutants and airborne bio-pathogens was achieved at a low specific input energy. This combined NTP-photocatalysis technology can be applied in multiple indoor settings, such as hospitals and public spaces, as well as in potential manned space missions.
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