Green electrospinning ethyl cellulose/chitosan bimodal nanofiber membrane based on internal-external synergistic enhancement strategy for high-flux air filtration.

The preparation of electrospinning air filtration membranes based on fully bio-based materials is the key to alleviate the energy and environmental crises. However, for the lack of reasonable materials matching and structural design strategies, it is difficult to balance the mechanical and filtration properties of bio-based fiber membranes. In this study, ethyl cellulose (EC)/chitosan (CS) bimodal nanofiber membrane was prepared by one-step electrospinning. In detail, EC was intended to construct a low binding energy system while CS was introduced to enhance split. And the ethanol and water were used as solvents. More importantly, the "internal-external synergistic enhancement strategy" was proposed creatively: on the one hand, the hydrogen bonding was enhanced for the incorporation of CS; on the other hand, bonding structures were formed among the fibers after the heating-annealing process, which was attributed to the melting and solidification of CS. The combination of hydrogen bonding and bonding structures dramatically improved the mechanical properties of the membrane. The elastic modulus and tensile strength of the 15EC/1.5CS membrane were 103.13 and 5.97 MPa. At 85 L/min, the filtration efficiency of 15EC/1.5CS membrane for PM0.3 was 99.01 %, the pressure drop was only 56.2 Pa, and the quality factor was 0.082 Pa-1.