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

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.