Spent Coffee Grounds‐Derived Micro‐Nano‐Architectured Air Filtration Membranes for Multiwavelength Light‐Triggered Bioaerosol Inactivation

ABSTRACT

Indoor air carries particulate matter, toxic gases, and viable microorganisms, yet filtration systems treat them separately at an added energy cost. We introduce a membrane that targets all three by spatially segregating two metal‐organic frameworks (MOFs) within a micro‐nanostructured architecture: one for gas adsorption, and the other is positioned at the particle‐capture interface. The membrane is fabricated in a single step by simultaneous electrospinning of MOF‐177‐loaded polyacrylonitrile nanofibers and electrospraying of ZIF‐8‐decorated spent coffee ground (SCG) microparticles. SCG, a waste stream exceeding 10 million tons annually, exhibits multiwavelength photothermal activity via bio‐derived chromophores and develops hydrophobicity upon mild annealing. At 4.5 times the NIOSH respirator test velocity, the membrane captures 99.7% of PM _2.5 at roughly half the pressure drop of an equivalent MOF‐free membrane, while removing 83.4% of ammonia vapor. The membrane reaches above 80°C under simulated sunlight, enabling chemical‐free, external‐power‐free microbial inactivation of accumulated bioaerosols; after 3 days of real office‐air exposure, a single 10 min simulated solar exposure or a 20 min near‐infrared (NIR) exposure restored effective microbial suppression. This establishes a generalizable principle: spatially resolved co‐deposition of multiple functional agents via twin electrohydrodynamic techniques can convert an organic waste stream into a self‐sterilizing air‐purification platform.