Corn-Based Biodegradable Air Filter with Ultra-High PM0.3 Filtration Efficiency
As industrialization and urbanization accelerate, particulate matter (PM) pollution has become a major threat to public health. Conventional air filters are typically made from petroleum-based synthetic materials such as polyester, polypropylene, or fiberglass, which are non-degradable and pose long-term environmental risks when incinerated or landfilled. Although biomass materials are seen as ideal alternatives due to their biodegradability, their inherent drawbacks—such as uneven pore structures and poor connectivity—make it difficult to effectively capture ultra-fine particles like PM0.3 (around 300 nanometers in diameter). Developing a high-efficiency air filter using biomass materials has remained a significant technical challenge.
A research team led by Professors Han Guangping and Cheng Wanli, and Associate Professor Wang Dong from Northeast Forestry University, in collaboration with researchers Ding Bin and Zhang Shichao from Donghua University, Professor Wei Yan from Tsinghua University, and Associate Professor Yue Yiying from Nanjing Forestry University, has successfully developed a fully bio-based high-performance air filter. This innovative filter is made from corn processing residues—corn protein and straw cellulose—and utilizes an eco-friendly electrospinning technique to create a dual-network structure composed of grooved microfibers (2.61 ± 1.11 μm) and nanofibers (0.29 ± 0.18 μm). The result is an air filter with over 99.99% PM0.3 removal efficiency and an ultra-low pressure drop of just 45 Pa. Importantly, the material is fully biodegradable, and life cycle assessments confirm its carbon footprint and overall environmental impact are significantly lower than conventional petroleum-based alternatives.
Innovative Dual-Network Structure from Corn Waste
The researchers innovatively combined the complementary properties of corn protein and straw cellulose, employing a “dynamic solvent exchange” process (Figure 1b). Under high humidity conditions (90%), an ethanol/water solvent (80:20 wt.%) evaporates from the spinning jet while ambient water vapor diffuses in, triggering a partial nonsolvent-induced phase separation. This creates a radial solvent gradient, causing the fiber surface to solidify first and form longitudinal grooves (Figure 1c). The addition of cellulose nanofibrils (CNFs) introduces viscoelastic mismatch with corn protein, leading to jet splitting (Figure 1d), and resulting in a one-step formation of the micro–nano intertwined dual-network structure (Figure 1e–f). This structure maintains an ultra-low pressure drop (45 Pa) while achieving 99.9994% PM0.3 filtration efficiency—outperforming traditional non-biodegradable filters (Figure 1g).
Figure 1 | Sustainable fabrication strategy, fiber formation mechanism, and dual-network (D-net) structure of corn-based electrospun fibers
a. Schematic of the design concept promoting green, circular, and low-carbon development.
b. Dynamic solvent exchange process driving incomplete non-solvent-induced phase separation.
c. Illustration of inward shrinkage mechanism based on a tubular fiber model controlled by solvent diffusion.
d. Jet splitting behavior induced by viscoelastic mismatch between corn protein and cellulose nanofibers (CNFs).
e. Schematic of the dual-network (D-net) architecture.
f. SEM image of the corn-based D-net membrane composed of microfibers and nanofibers.
g. Comparison of PM0.3 filtration efficiency and pressure drop between this study and various previously reported filtration technologies.
Superior Structural and Functional Performance
The dual-network architecture significantly enhances material performance (Figure 2a–b). Nanofibers (0.29 ± 0.18 μm) fill the gaps between microfibers, raising porosity to 94.62% (Figure 2g) and reducing the dominant pore size to 1–4 μm (Figure 2h). Confocal microscopy reveals CNFs aligned along the fiber axis (Figure 2d), reinforcing groove depth and improving particulate capture. Rheological tests show that adding CNFs dramatically increases solution viscosity (Figure 2e), facilitating stress concentration during spinning. FTIR analysis confirms that corn protein and CNFs are bound through physical interactions like hydrogen bonding, without introducing harmful chemical residues (Figure 2f).
Figure 2 | Structural properties of the corn-based filtration membrane
a–b. SEM images of (a) pure corn protein fibers and (b) corn protein/CNFs composite fibers under 90% relative humidity (RH).
c. Diameter distribution of D-net fibers.
d. Confocal laser scanning microscopy (CLSM) image of D-net fibers labeled with FITC-zein (corn protein) and CW-CNFs.
e. Viscosity changes of corn protein and corn protein/CNFs solutions during solvent evaporation.
f. FTIR spectra of CNFs, D-net fibers, corn protein, and raw corn protein.
g–h. (g) Porosity and (h) pore size distribution of corn-based membranes with ribbon-like, rod-like, and D-net structures.
i. Cross-sectional SEM images of fibers with ribbon-like structure (RH 30%) and rod-like structure (RH 90%).
(Note: Data are presented as mean ± standard deviation, n = 5; see source data file for details.)
Real-World Performance and Pollutant Removal
Application tests (Figure 3a–c) demonstrate the outstanding performance of the ultra-lightweight corn-based membrane (10.2 g·m⁻²): at a wind speed of 5.33 cm·s⁻¹, it achieves 99.9994% PM0.3 capture with just 45 Pa pressure drop—meeting ULPA (ultra-low penetration air filter) standards. Even at 16.6 cm·s⁻¹ (medical respirator standard), filtration efficiency remains above 98.5%. Formaldehyde adsorption capacity is also remarkable: in 240 minutes, the filter absorbed 1.26 times its own weight in formaldehyde (Figure 3f), far outperforming commercial HEPA filters, which managed only 0.017 times (Figure 3e). Mechanistic studies (Figure 3g) reveal a “full-structure filtration” mechanism: grooved microfibers embed particles, while nanofibers adsorb them via charge, polarity, and hydrogen bonding, jointly overcoming the size-sieving limitation of traditional filter media.
Figure 3 | Functional mechanisms of air filtration and formaldehyde adsorption
a. PM0.3 filtration efficiency and pressure drop of corn-based membranes with different structural types (airflow velocity: 5.33 cm·s⁻¹).
b. PM0.3 filtration performance of D-net membranes with varying basis weights (airflow velocity: 5.33 cm·s⁻¹).
c. PM0.3 filtration efficiency and pressure drop of a D-net membrane (basis weight: 11.6 g·m⁻²) under different airflow velocities.
d. Comparison of filtration efficiency and pressure drop between commercial filters and D-net membranes.
e. Comparison of formaldehyde adsorption efficiency between the corn-based D-net membrane and commercial HEPA filters.
f. Time-dependent relative weight gain of formaldehyde adsorption on the corn-based D-net membrane.
g. SEM image illustrating the full-structure filtration mechanism of the D-net membrane, including embedded PM0.3 capture.
(Note: Data are presented as mean ± standard deviation, n = 5; see source data file for details.)
Life Cycle and Environmental Sustainability
Life cycle assessment (Figure 4a–b) shows the corn-based membrane outperforms petroleum and fiberglass filters across all environmental metrics, including fossil resource use, marine eutrophication, and ecotoxicity. Its biodegradability is especially important: the material fully decomposes in soil within two weeks (Figure 4c), and degrades gradually in phosphate-buffered solution (Figure 4d), eliminating the need for post-use recovery and enabling a true cradle-to-cradle lifecycle.
Figure 4 | Environmental feasibility of the corn-based filtration membrane
a. System boundary of the life cycle assessment.
b. Environmental impact comparison among corn-based, polyester, polypropylene, and fiberglass filtration materials.
c–d. Degradation behavior of corn-based membranes (15.5 cm × 7.5 cm) under different conditions: (c) soil burial and (d) PBS solution immersion.
Conclusion: A Breakthrough in Sustainable Air Filtration
This breakthrough offers a new paradigm for developing sustainable, high-performance filtration materials. By turning agricultural waste into a biodegradable dual-network structure, the team has achieved both ultra-high PM0.3 filtration efficiency and ultra-low airflow resistance. Looking ahead, this type of material can be used independently or integrated into respiratory protective equipment, HVAC systems, medical devices, and engine air intakes—accelerating the transition to greener, low-carbon air filtration technologies.
