Wastepaper-Based Cylindrical Hollow Air Filter Module for the Removal of Particulate Matter (PM₁₀ and PM_2.5) and HCHO

Abstract

A wastepaper (WP)-based cylindrical hollow air filter (CHAF) is prepared by oxidative heat treatment of WP fragments, followed by vacuum filtration of a WP solution to form a WP column that underwent boring. The CHAF shows excellent PM2.5 removal efficiency (99.12%) and an extremely low pressure drop (4 Pa) at a flow rate of 1.5 m/s because of the structural and chemical characteristics of the CHAF. CHAFs that are connected in series and parallel demonstrate the advantages of an increased removal efficiency and a decreased pressure drop, respectively. Thus, combinations of CHAFs connected in series and parallel further increase the PM2.5 removal efficiency and decrease the pressure drop at a high PM2.5 concentration of 644,000 μg/m3 and a high flow rate of 5–10 m/s. The CHAFs are also able to simultaneously remove particulate matter (PM) and formaldehyde (HCHO) at very low concentration levels (below 0.1 ppm). A miniature air cleaner equipped with the CHAF can effectively remove 5 L of PM2.5 at extremely high concentrations of over 650,000 μg/m3 and a high flow rate of 5 m/s with a high efficiency (99.24–96.88%), low pressure drop (31–34 Pa), and short removal time (3.5 min) for up to 270 cycles.