Biogenic CaO Nanoparticles-Loaded Chitosan/PVA Electrospun Nanofibers for Antibacterial Water Disinfection

Abstract

Chitosan-based nanofibers are especially attractive owing to their biodegradability, biocompatibility and intrinsic antibacterial activity. In present study, chitosan/poly(vinyl alcohol) (PVA)/calcium oxide (CaO) composite nanofibers were fabricated by electrospinning using CaO nanoparticles derived from eggshell waste as a sustainable antibacterial additive. Chitosan and PVA were blended to improve solution spinnability, fiber continuity and mechanical integrity, while biogenic CaO nanoparticles were incorporated to enhance antibacterial performance. The optimized formulation produced uniform nanofibers with diameters in the range of approximately 100-250 nm. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) confirmed the formation of the composite matrix, intermolecular interactions between chitosan and PVA and the incorporation of CaO nanoparticles. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed smooth, bead-free fibers with a porous interconnected morphology and thermogravimetric analysis (TGA) indicated the presence of thermally stable inorganic residue. The nanofibers showed pronounced antibacterial activity against Escherichia coli in the agar well diffusion assay. Freshly prepared fibers produced an inhibition zone of 2.0 cm, while fibers stored for one month retained substantial activity with an inhibition zone of 1.8 cm. The antibacterial effect is attributed to the combined action of chitosan-mediated membrane disruption and CaO-induced alkaline/oxidative stress. These results indicate that biodegradable chitosan/PVA/CaO electrospun nanofibers have potential as eco-friendly antibacterial materials for decentralized and portable water disinfection applications. Water disinfection performance was further assessed using a most probable number (MPN) assay with contaminated canal water. Following 10 min of direct contact with the nanofiber membrane, coliform-positive responses and gas formation were substantially reduced, supporting the use of the composite for rapid point-of-use water disinfection.