Banana crop biomass-derived chemically activated filters for concurrent removal of particulate matter and volatile organic compounds

Abstract

Air pollution caused by particulate matter (PM) and volatile organic compounds (VOCs) poses a critical threat to public health, contributing to millions of premature deaths each year. This growing problem underscores the urgent need for sustainable and efficient air filtration systems. This study presents the development of biodegradable filters based on biomass from banana cultivation in the Canary Islands, a residual and abundant natural resource, enabling dual valorization by using the cellulose as a structural matrix and the same biomass to produce activated carbon. Filters were fabricated via freeze-drying and incorporated activated carbon produced through chemical activation with H3PO4 or KOH at varying concentrations. Comprehensive characterization was conducted using scanning electron microscopy, Fourier-transform infrared spectroscopy, and porosity analysis, in addition to performance testing for both PM filtration (0.3-10 mu m) and toluene gas adsorption. Filters with 10 % H3PO4-activated carbon showed the highest PM filtration efficiency, reaching 95 % for particles >= 0.5 mu m and exceeding 90 % for submicron particles, with cumulative efficiencies over 80 % for PM2.5 and PM1. These results were attributed to higher surface area and internal porosity, though accompanied by an increased pressure drop (similar to 800 Pa). In contrast, KOH-activated carbon demonstrated superior toluene adsorption capacity, remaining unsaturated for up to 350 min, due to its surface functional groups' greater affinity for non-polar compounds. The findings reveal a functional complementarity between both activation methods, allowing for the design of application-specific or dual-layer multifunctional filters. This work supports the use of banana biomass as a sustainable alternative to synthetic materials in air pollution control technologies.