Bio-based electrospun polyamide membrane – sustainable multipurpose filter membranes for microplastic filtration†

Electrospinning is a highly versatile method for manufacturing filter membranes, contributing to advanced concepts for the production of sustainable membranes for waste water treatment. The use of bio-based polymers could expand the sustainability of such filter membranes significantly. Bio-based PA 6.9, for example, shows great potential for the creation of bio-sourced electrospun filter membranes (EFMs) with high mechanical properties and high resistance to solvents. The polyamide is synthesized from plant oil-based azelaic acid and electrospun from chloroform/formic acid to produce self-standing electrospun nonwovens. These highly porous membranes show high efficiencies of up to 99.8% for the filtration of polystyrene microparticles (PS-MPs) from water. Additionally, the electrospun nonwovens exhibit comparable filtration efficiencies to FFP3 masks for the removal of 0.3 μm particles from air. The membranes show hydrophobic surface behavior (water contact angle of >120°) making them suitable for water oil separation. Efficiencies of up to 99.9% can be achieved for the separation of water and chloroform from 50 vol% mixtures, while maintaining a high permeate flux of up to 5345 L m⁻² h⁻¹. Additionally, the membranes can be reused for at least ten times without any significant reduction in efficiency or flux.