Silk Nanofibrillar Aerogel as Sustainable Filters for Environmental Purification

Environmental pollution threatens human health and ecosystem sustainability, boosting a huge demand for filters. However, the petroleum-based filters are likewise environmentally hazardous since their non-degradability results in disposal in landfills. Although biodegradable synthetic polymers have been contemplated as alternative filtration materials, their utilization in fabricating ultrafine fibers to construct effective 3D filters remains an obstacle. In this study, all-biomass nanofibrous filters are developed with versatility and biodegradability based on silk nanofibrils (SNFs). Bulk aerogels with tunable structures can be fabricated through solvent-mediated ice crystal growth by using SNFs as a building block. The SNF-based aerogel exhibited excellent water purification performance, as evidenced by their ability to remove micro-nano plastics, organic dyes, and heavy metal ions. The practicability of this filter system is demonstrated by the successful production of purified water from simulated polluted water and dirty river water. Moreover, the versatility of the SNF aerogel is further proven by superior air filtration performance against PM_0.3 and oily smoking. Furthermore, the SNF aerogel filter has a low environmental impact as it can be safely biodegraded in the natural environment, with a ratio of 73.8% after one year of landfill. This work provides a path toward sustainable purification treatment of environmental pollution.