Electrospun Chitosan/Poly (vinyl alcohol) grafted biopolymer composite membranes with enhanced mechanical and antifouling properties

Chitosan, as a renewable biological macromolecule, has attracted increasing interest for membrane engineering owing to its abundant functional groups and strong affinity toward metal ions. In this study, waste-derived chitosan extracted from recycled oyster shells was blended with poly (vinyl alcohol) (PVA) and fabricated into electrospun nanofibers, which were subsequently grafted onto cellulose acetate reverse osmosis (CA-RO) membranes to form biopolymer composite membranes. The macromolecular structure, intermolecular interactions, and physicochemical properties of the resulting membranes were systematically investigated using SEM, XRD, and FTIR analyses. The electrospun CS/PVA fibers exhibited diameters ranging from 182 to 459 nm, with higher electrospinning voltages yielding thinner and more uniform fibers. Grafting of the CS/PVA fibers significantly enhanced membrane hydrophilicity, reducing the water contact angle from 68.21° to 51.2°, and improved mechanical performance, with tensile strength increasing from 86.17 MPa to 144.55 MPa. These improvements are primarily attributed to hydrogen bonding and macromolecular chain interactions between chitosan, PVA, and cellulose acetate. The functionalized composite membranes demonstrated high rejection efficiencies for Pb(II), Cu(II), and Cd(II), with minimal impact on water permeability. The CS/PVA/CA-RO composite membranes exhibited high heavy metal rejection efficiencies of 85.98%, 90.51%, and 95.31% for Pb(II), Cu(II), and Cd(II), respectively, while maintaining a water flux of 9.96 L·m −2 ·h −1 highlighting the effective integration of adsorption functionality with structural stability. This work presents a sustainable macromolecular engineering strategy for designing high-performance biopolymer composite membranes via electrospinning and surface grafting, offering promising potential for advanced separation applications.