Environmentally Sustainable Particulate Filter Fabricated via Induced Phase Separation of Bioderived Fungal Chitin and Poly(lactic acid)

With the increasing demand for filtering face pieces as daily personal protection, inevitable problems associated with filter wastes have been addressed. To mitigate this concern, an eco-friendly alternative filter material is developed using plant-sourced biomaterials, poly(lactic acid) (PLA) and fungal chitin. Heterogeneous electrospun fibers with distinctive chitin-rich and PLA-rich regions are formed by inducing phase separation between hydrophilic chitin and hydrophobic PLA polymers. The PLA and chitin-incorporated PLA (ChPLA) webs are evaluated for filtration performance against NaCl nanoparticles, examining the contribution of mechanical and electrostatic particle capture mechanisms, with and without aging under two different environmental conditions of 40 °C and a 3% relative humidity and 25 °C and a 90% RH. The adverse effect of humid treatment on filtration efficiency is apparent for the ChPLA web, and the loss of overall filtration efficiency is mostly attributed to the reduced electrostatic filtration mechanism, as is evidenced by the decreased surface potential measurement. The ChPLA web displays lower tensile stress than the PLA web, and the mechanical strength is further reduced when ChPLA is exposed to moisture. In the soil burial test, ChPLA shows higher degradability than PLA during 56 days of burial. This research provides practical information to design environmentally sustainable filter media, primarily with biobased polymers, especially shedding light on accelerated biodegradation via induced phase separation.