Delignified wood filter functionalized with metal-organic frameworks for high-efficiency air filtration

Particulate matter (PM) pullution has emerged as a global concern. Herein, delignified wood functionalized with metal–organic frameworks (MOFs) was investigated for efficient PM removal. In particular, the lignin removal was realized by a deep-eutectic-solvent assisted process. By integrating three different MOFs into the porous wood matrix, wood-based filters with hierarchical structure were fabricated. The MOF particles including ZIF-8, MOF-199 and UiO-66 were deposited on the filters through in situ growth approach, thereby leading to a uniform MOF dispersion and strong wood-MOF adhesion. The ZIF-8 functionalized wood filter exhibited the highest PM removal performance, with PM 2.5 and PM 10 removal efficiencies of 89.8% and 91.6%, respectively. The superior PM capture ability of ZIF-8@Wood is attributed to the suitable surface property and sophisticated channels/pores. The gas transport pathways and PM capture mechanisms within wood filter were discussed in detail. This cost-effective and environmentally friendly filtration device provides a novel material platform for PM removal, and it could be extended for hazardous gas capture and volatile organic compound adsorption.