Sustainable and cost-effective antimicrobial cellulose filter papers functionalized with tannic acid-mediated silver and zinc oxide nanoparticles

This research describes a sustainable method for water purification using antimicrobial cellulose filters functionalized with silver and zinc oxide nanoparticles. Using the coordination chemistry of main group elements, citric acid and chitosan were employed to modify a biodegradable cellulose scaffold (Group 14 and 16 biopolymers). Tannic acid, an oxygen-rich plant polyphenol, served as a reducing and capping agent to immobilize nanoparticles. The resulting composites were characterized via FT-IR ATR, XRD, and SEM-EDX, confirming successful grafting and uniform distribution within the biopolymer matrix. Filtration assays against Staphylococcus aureus , Escherichia coli , and Candida albicans demonstrated significant efficacy. Silver-loaded filters achieved near-complete inactivation of E. coli (∼99.84%), while zinc-loaded filters excelled against S. aureus (∼99.78%) and C. albicans (∼96.79%). Dual-metal filters provided balanced antimicrobial action (90.28–95.13%). Release assays confirmed minimal leaching, with negligible nanoparticle detachment and only trace organic release, ensuring environmental safety. This work highlights how the manipulation of main group chemical environments, specifically carbon, oxygen, and nitrogen-based ligands, facilitates metal stabilization. These eco-friendly filters offer a cost-effective solution for water disinfection in low-resource settings.