A Packed-Type Reconfigurable Air Filtration System for Removal of Particulate Matter and HCHO

A flexible and packed-type air filter ball (AFB) system was developed for the efficient removal of particulate matter (PM) and formaldehyde (HCHO). The Mg/Si-embedded AFB (Mg/Si-AFB) was synthesized through sequential physical etching of a sponge, oxidation of glass fiber, and subsequent formation of Mg-Si components. The resulting Mg/Si-AFB exhibited a highly porous and roughened architecture with enhanced surface reactivity. A disk-type filtration device loaded with Mg/Si-AFBs demonstrated a PM_2.5 removal efficiency (RE) of 97.4% at a pressure drop of 57 Pa. The RE increased with packing density and PM concentration and notably remained constant even at high air velocities (7 m/s). In addition, the oxidized glass fiber (GF)-based AFB (O-GF-AFB) exhibited rapid HCHO adsorption capability, achieving 100% HCHO removal within 1 min. Hybrid air filters combining Mg/Si-AFBs and O-GF-AFBs in an equal ratio (8:8) exhibited synergistic performance, simultaneously achieving 97.1% PM_2.5 RE and complete HCHO removal within 1-6 min, while maintaining low pressure drops (55-57 Pa) over 50 reuse cycles.