The majority of raw materials used for filtration are not sustainable, as they are mainly plastics of fossil origin -such as polyethylene, polyester and polyamide- which are poorly biodegradable. As a result, they accumulate, rather than decompose, in the natural environment. The fate of these products is becoming an urgent environmental issue, as the case of disposable masks, recently considered as a threat to the oceans.

As an alternative, the use of biopolymer is considered a viable perspective to reduce the environmental impact of filter devices. To this purpose, we investigate the use of silk fibroin (SF) for the conception of high-performance filtration media.

In this work, SF membranes have been successfully fabricated by a green electrospinning process, which uses water as solvent. To control the viscosity of the solution, a reduced amount of polyethylene oxide (PEO) is employed, in a final ratio 70:30 with respect to the amount of fibroin. The obtained electrospinning solution is a mixture of water, silk fibroin, and PEO, resulting in a non-toxic precursor solution.

By varying the time deposition of electrospinning, we evaluated the effect of the weight factors on the filtration performance of SF membranes. Efficiency is tested by measuring the penetration of NaCl aerosols through the membranes, at a fixed velocity of 5.3 cm/sec. The pressure drop is measured by a differential pressure gauge (Testo Manometer 512). Quality factor is retrieved from pressure drop and filtration efficiency at the most penetrating particle size.

Results show a significant anti-correlation between ...