Hierarchical fiber with granular-convex structure for highly efficient PM2.5 capture

•A high-efficiency, ecofriendly and biosafety fiber membrane was prepared.•The hierarchical fiber with novel granular-convex structure was fabricated.•The ecofriendly and sustainable method were carried out during the preparation process.•The hierarchical fiber membrane exhibited excellent filtration performance. Air pollution has seriously affected human health and the atmospheric environment. Preparation of fiber membrane with hierarchical structure provides an advanced method for high-performance air filtration. However, indistinctive secondary structure and complicated preparation present constantly in the formation of fiber with hierarchical structure, inevitably limited in the application of air filtration. In this work, a typical granular-convex structure was created in the surface of thermal-crosslinked sodium phytate/polyvinyl alcohol (T-PANa/PVA) fiber via green preparation. Unique secondary structure endowed fiber with efficient physical interception and polar adsorption, which exhibited excellent the removal of air pollutants (removal of PM2.5 high than 99.9% while low air resistance of 36.5 Pa). In addition, due to the exist of crosslinked network, T-PANa/PVA fiber membrane expresses water-resistant and mechanical properties. This work provides a positive strategy to fabricate hierarchical fiber membranes via green preparation for high-performance air filtration, which is expected to substitute traditional air filtration materials and adapt to the sustainable development of future.