Air filters fabricated by fibrillated lyocell fibres and polyethylene terephthalate fibres with implantation of cellulose nanofibrils for high-efficiency particulate matter removal

Air pollution has become a serious threat to human health; hence, it is highly desirable to develop high-efficiency air filters. In this paper, porous cellulose nanofibril (CNF)-implanted air filters with hierarchical structures consisting of LC/PET/CNF composites were prepared using pressurized filtration. The frame of the composite was made of fibrillated lyocell fibres (LC), while polyethylene terephthalate (PET) fibres acted as spacers between the fibrillated LC fibres. CNFs serving as functional fillers were implanted in the LC/PET composite to decrease pressure drop. The results showed that the overall filtration efficiency of the LC/PET composite (50%:50%) with a basis weight of 30 g/m2 for particulate matter (PM) was only 52.69%, while the pressure drop was 56.50 Pa. However, after implantation of CNFs in the LC/PET composite with a weight concentration of only 0.5 g/m2, the overall filtration efficiency significantly improved to 98.22% with an acceptable pressure drop of 145.50 Pa (P50W30t3N0.5). The study provides a new way to achieve high-efficiency fabrication of air filters with high performance for PM removal.