Green‐Solvent‐Processable Composite Micro/Nanofiber Membrane with Gradient Asymmetric Structure for Efficient Microfiltration

Abstract

Electrospinning technology has attracted extensive attention in recent decades and is widely used to prepare nanofiber membranes from hundreds of polymers. Polyvinyl formal acetal (PVFA), as a polymer with excellent properties such as high strength and heat resistance, is not reported on the electrospun water treatment membrane. In this paper, the preparation process of electrospun PVFA nanofiber membrane is optimized, and the effect of sodium chloride (NaCl) addition on the physical and mechanical properties and microfiltration performance of nanofiber membrane is also explored. And the hydrophobic PVFA nanofiber filter layer is then combined with a hydrophilic nonwoven support layer to construct a composite micro/nanofiber membrane with a pore‐size gradient structure and a hydrophilic/hydrophobic asymmetric structure. Finally, unidirectional water transport and water treatment performance are further investigated. The results show that the tensile breaking strength of the composite membrane can reach up to 37.8 MPa, the retention rate for particles with the size of 0.1–0.3 µm is 99.7%, and the water flux is 513.4 L m−2 h−1 under the hydrostatic pressure. Moreover, it still has a retention of more than 98% after three repeated uses. Therefore, the electrospun PVFA composite membrane has a great potential in microfiltration.

Fabrication of PS/PVDF-HFP Multi-Level Structured Micro/Nano Fiber Membranes by One-Step Electrospinning

“…However, as technology advances and evolves, fiber membranes with a uniform diameter distribution are insufficient for application and are relatively more susceptible, limiting their use in practical applications. As a novel type of fiber membrane material, micro/nano fiber membranes with coarse and fine overlapping multi-stage structures are attracting attention because of their greater specific surface area [6], high porosity [7], high permeability flux [8], and high stability [9].…”