Polyelectrolyte aerogels with regeneration capacity for efficient removal of particulate matters

With the rapid development of economy and global industrialization, the problem of air pollution has become a worldwide topic. The efficient filtration of airborne particulate matters (PMs) is critical for human health and environmental sustainability.

Herein, self-supporting bio-based polyelectrolyte aerogels were prepared and acted as the advanced filters for efficient removal of PMs. The natural choline cation (Ch⁺) or the organic cation, 1-butyl-3-methylimidazolium (Bmim⁺), are introduced into alginate (Alg^-) to form the polyelectrolytes of ChAlg or BmimAlg due to the electrostatic interaction. By the directional freeze-drying in liquid N₂, hierarchically porous aerogels with mechanical robustness, flexibility and thermo-stability were prepared. This specific structure may permit the polluted air to pass adequately through the aerogel channels, which are conducive to intercept various PMs with different diameters.

As an example, the removal efficiency of ChAlg aerogels for PM₁₀, PM_2.5 and PM_0.3 are respectively up to (99.24 ± 0.03)%, (99.22 ± 0.02)%, and (93.41 ± 0.22)% within 15 h durability test. One outstanding character lies in ensuring high removal efficiency, while achieving a good balance with the low pressure drop (10 Pa), which is driven by synergistic effect of passive trapping and electrostatic capture. Moreover, the polyelectrolyte aerogels exhibit excellent antimicrobial activity and regenerated capacity. These properties endow the aerogels of polyelectrolyte ChAlg or BmimAlg with remarkable potential as new advanced filters for masks and other personal protective equipment.