Large-Scale Fabrication of 3d Gradient Hierarchical Fibrous Filter Materials with Micro-Submicro-Nanofibers for Efficient and Long-Duration Air Filtration

Atmospheric particulate matter pollution poses significant threats to human health and the environment. Submicron-fiber filtration materials have received widespread attention owing to their ultrafine dimensions, high porosity, and precise interception capabilities. However, their low dust-holding capacity and rapid resistance increase during use remain challenges. In this study, a modular helical linear free-surface multi-jet electrospinning device was employed to prepare multi-scale fibers (80–800 nm) and combine them with melt-blown non-woven fabrics in a single-step process, creating a three-dimensional gradient hierarchical filtration material (3D-MNFG). The 3D-MNFG exhibits a layered structure with gradient pore sizes transitioning from 18–32 μm to 0.5–2.4 μm, and 0.3–0.4 μm. Under an initial pressure decrease of 90 ± 3 Pa, it achieves high filtration efficiency (97%) and a quality factor of 0.038 Pa−1, even after electrostatic treatment. Furthermore, this novel material overcomes the limitations of existing submicron-fiber membranes by offering a dust holding capacity of 22.02 g/m2. In dynamic filtration tests at high air velocities (28 m/s), its resistance increased gradually, reaching its lifespan limit (450 Pa) after 29 d, significantly outperforming submicron-fiber materials, which saturated within 8 d. Simulations and dynamic tests validate the synergistic filtration mechanism of its multi-scale micro/nano-fibers. The fabricated filtration material shows promising potential for industrial production and commercial applications.