Study of the PTFE multi-tube high efficiency air filter for indoor air purification

Abstract Particulate matter air pollution has become a severe environmental issue because it poses a great threat to human health. In this work, a new type of Polytetrafluoroethylene (PTFE) multi-tube high efficiency particulate air filter was successfully prepared by applying PTFE sheet membranes that wrapped the nonwoven tube for the improvement of the indoor air quality. The properties and filtration performance of three types of PTFE sheet membranes were explored. The PTFE tubular membrane filters with different diameters, lengths and membrane layers were prepared and tested for the ability to remove particulate matter. The results revealed that the PTFE sheet membranes had excellent hydrophobicity and possessed the microstructure of nodes interconnected by fibrils. The thicker and smaller pore size membranes had higher efficiency, and the efficiency curves for the PTFE sheet membranes demonstrated the typical shape of a “V” from 10 to 300 nm at face velocities from 0.3–15 cm/s. The best type of tubular membranes in terms of diameter and length was dependent on the packing density and the height of the filter cavity. According to the test results, the filter contained two layers of membranes had the lowest pressure loss while achieving an ultra-high particle removal efficiency of over 99.98 % for particles (0.3 μm) and nearly 100 % for particles (2.5 μm). The fouling tendency in the staggered arrangement of tubes was less than that in the aligned arrangement. Therefore, the PTFE multi-tube air filter based on the sheet membrane might have a positive potential application for PM removal from air pollution.