Exploring the antimicrobial properties of dark-operating ceramic-based nanocomposite materials for the disinfection of indoor air.

As people spend more and more time inside, the quality of indoor air becomes crucial matter. This study explores the germicidal potential of two dark-operating germicidal composite materials designed to be applied for the indoor air disinfection under flow conditions. The first material, MnO2/AlPO4/γ-Al2O3 beads, is a donor-acceptor interactive composite capable of creating hydroxyl radicals HO∙. The second one is a ZnO/γ-Al2O3 material with intercropped hexagons on its surface. To determine the antimicrobial efficiency of these materials in life-like conditions, a pilot device was constructed that allows the test of the materials in dynamic conditions and agar diffusion inhibitory tests were also conducted. The results of the tests showed that the MnO2/AlPO4/γ-Al2O3 material has a germicidal effect in static conditions whereas ZnO/γ-Al2O3 does not. In dynamic conditions, the oxidizing MnO2/AlPO4/γ-Al2O3 material is the most efficient when using low air speed whereas the ZnO/γ-Al2O3 one becomes more efficient than the other materials when increasing the air linear speed. This ZnO/γ-Al2O3 dark-operating germicidal material manifests the ability to proceed the mechanical destruction of bacterial cells. Actually, the antimicrobial efficiency of materials in dynamic conditions varies regarding the air speed through the materials and that static tests are not representative of the behavior of the material for air disinfection. Depending on the conditions, the best strategy to inactivate microorganisms changes and abrasive structures are a field that needs further exploration as they are in most of the conditions tested the best way to quickly decrease the number of microorganisms.