Recyclable aligned carbon nanotube-sheet-based particulate air filter with high filtration efficiency and low pressure drop

There is an increasing demand for particulate matter filters to primarily block viruses and fine particulate matter floating in the air from entering the human body. The most commonly used microfiber-based filter has a technical flaw in which the filtration efficiency cannot be maximized as there is a trade-off in terms of performance; the pressure drop increases when the filtration efficiency increases. Here, we report the development of a recyclable macroscopic carbon nanotube (CNT)-based filter consisting of unidirectionally arranged multi-walled carbon nanotube sheets. Owing to the uniform arrangement of the 10–20 nm carbon nanotubes, uniform nanopores are formed. As a result, the CNT-sheet-based particulate matter filter exhibited low pressure drop characteristics, even at a high filtration efficiency. In addition, it was confirmed that the collected particulate matter could rapidly be removed through heat generated by applying a voltage to the conductive CNT sheet.