An eco-friendly, dual-dimensional and multi-functional fibrous filter enables efficient indoor air purification

Abstract

Indoor air quality has garnered critical concern, driven by the pervasive presence of fine particulate matter (PM) and toxic gases such as formaldehyde. Despite the advancements in filtration technologies, developing sustainable filters that deliver efficient air purification without an increase in pressure drop remains a formidable challenge. Here, we present a straightforward and scalable fibrillation strategy for fabricating sustainable and efficient air filters composed of micro-/nano-fibres. By sonicating lyocell nonwovens in an NaOH solution, followed by stirring in water, we integrated chemical hydrolysis, ultrasonic cavitation and vortex shearing to generate abundant nanofibrils on the microfibre surface. The elongation and entanglement of these nanofibrils resulted in a stable nanofibre network with an enlarged specific surface area (SSA) and reduced pore size, thereby enhancing the filtration efficiency (78.1%) while maintaining an ultralow pressure drop (7.4 Pa). Furthermore, synthesis and loading of hydroxyapatite (HAP) catalysts onto the nonwovens revealed a significant increase in the catalyst loading capacity after fibrillation. The resultant filter exhibited a high removal efficiency for both PMs (81.7%) and formaldehyde (99.1%) at room temperature. We believe that the combination of a biodegradable dual-dimensional fibrous network with an eco-friendly catalyst may provide a major inspiration for developing next-generation indoor air filters.