Silk-Based Fine Dust Filters for Air Filtration

State-of-the-art air filter devices have been well-characterized and optimized for particle deposition of a huge range of particle sizes. However, sustainability of the employed filter materials is usually neglected. In this study, several polymers (recombinant spider silk, recombinant lacewing silk, poly(lactic acid), and poly(ethylene oxide)) are electrospun into fine dust filter layers to evaluate relevant filter parameters such as particle deposition, air permeability, and pressure drop for sub-micrometer fiber materials. Filters comprising silk proteins show a much lower demand on fine-dust-layer material (40-210 mg m(-2)) in comparison to that of conventional filters (50 g m(-2)). Filters equipped with silk meshes with fiber diameters in the sub-micrometer regime (<250 nm) show improved filter qualities in comparison to that of commercially available air filter devices (with melt blown fibers in the >20 mu m regime). In particular, sub-micrometer particles (0.2-1 mu m) are filtered more efficiently by the silk-based filters due to interception and impaction effects yielding a low pressure drop, and therefore these filters show an improved air permeability and lowered pressure drop of, for example, a vacuum cleaner bag in which they can be employed.