Virus Inactivation by Catalytic Air Converter Filters: The Role of Coating Methods

The airborne transmission of pathogens presents a high risk of infection in closed environments, where we spend more than 85% of our time. These infectious respiratory particles contaminated with pathogens remain infectious for hours and can be transported over long distances. To mitigate this threat, it is necessary to develop technologies that can remediate, remove, or decrease airborne pathogen concentration or infectivity in air. In this work, patented catalytic polymeric converter filters were prepared by spray coating and dip coating. The preparation of spray-coated filters was optimized by evaluating the effect of the air pressure and the distance between the filter and the airbrush. Micrographs and hyperspectral Raman maps demonstrated that the air converter filters prepared by spray coating present a more homogeneous coating than the dip-coated sample. Converter filters prepared by spray coating at 1 bar and a 6 cm airbrush-filter distance showed the best coverage. Moreover, this optimum filter exhibited the best adherence, with a mass loss of 0.5% after 180 min of ultrasound treatment. This catalytic polymeric converter filter has shown a reduction of 4 logarithm units after 60 min of exposure to HCoV-229E at room temperature. Overall, this work introduces an optimized spray-coating method as a low-cost and simple process to prepare a biocidal catalytic polymeric converter filters.