Development of carbon nitride-modified air filters for removal of airborne bacteria and viruses

A few years ago, millions of people died worldwide as a result of the fast-spreading coronavirus known as SARS-CoV-2 and the condition it caused, known as COVID-19. Additionally, another similar virus, influenza A, has also been reported to cause respiratory problems in healthy people. Because these diseases travel through the air, they are difficult to control. Since it is impossible to completely avoid these airborne diseases, the development of highly efficient antimicrobial air filters is required, as people cannot rely solely on protections such as social distancing and wearing masks. In the past few decades, nanotechnology has emerged as a promising field in the fight against infectious diseases. For example, various nanomaterials with outstanding physical and chemical properties have been extensively explored in biomedical applications such as the development of vaccines, drug delivery, and antibacterial treatments. Previous studies have shown that the application of metal based and metal oxide nanoparticles, including copper oxide (CuO) and silver oxide (Ag2O), as excellent antiviral and antibacterial filters, when coated on air filters. However, one of the limitations is that they cannot be simply disposed of, as they can be harmful to the environment. Therefore, in these studies, the use of sustainable nanomaterials that are environmentally friendly will be prioritized. Recently, graphitic carbon nitride (CN) has emerged as a prominent and sustainable photocatalyst, providing an innovative solution to address the environmental and energy challenges. However, since most of the reported CN absorbs light only up to 450 nm, it might not work well under solar light irradiation. Therefore, modification of CN with a dopant that can extend its light absorption to 700–800 nm is highly recommended. In this part, a red dopant (2,4,6-triaminopyrimidine) will be incorporated into the framework of CN, and the home air filters will be coated with the respective modified CN using nanospray drying. This product is expected to prevent the spread of a wide number of respiratory infections. Moreover, this study would also specifically investigate the effectiveness of the modified air filters to prevent the growth of two specific respiratory pathogens such as Streptococcus pneumoniae and Pseudomonas aeruginosa.