Mesh-Engineered Photocatalyst/Hydrogel Composite for Sustainable Removal of PM2.5-Bound Polycyclic Aromatic Hydrocarbons

Airborne polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants that pose significant risks to human health. In this study, a photocatalyst-based polyacrylamide/zinc oxide (PAM/ZnO) hydrogel composite mesh with an open-mesh architecture was successfully fabricated via photoinduced polymerization of acrylamide, in which ZnO served as both the photoinitiator and photocatalyst. The resulting composite exhibited a three-dimensional interconnected porous structure with ZnO particles uniformly distributed throughout the polyacrylamide hydrogel matrix. The hydrogel exhibited typical swelling–deswelling behavior, reaching an equilibrium swelling ratio of 2.71 within 360 min, along with good water-retention capability. The photocatalytic performance of the PAM/ZnO hydrogel composite mesh was evaluated through the degradation of particulate matter (PM)-bound PAHs generated from incense smoke. The concentrations of two- to five-ring PAHs progressively decreased with increasing ultraviolet irradiation time. Complete degradation of naphthalene was achieved after 4 h of UV irradiation, whereas all detected five-ring PAHs were completely removed after 8 h. Furthermore, the mesh-engineered architecture exhibited excellent air permeability with an exceptionally low pressure drop (<120 Pa), even with multiple mesh layers, enabling energy-efficient continuous air recirculation. These characteristics, together with the photocatalytic degradation of particle-bound PAHs, make the PAM/ZnO hydrogel composite mesh a promising platform for sustainable air purification.