Fabrication and characterization of PVA, PVA/chitosan, and PVA/cyanobacterial exopolysaccharide nanofibrous composite nanofiltration membranes prepared by electrospinning

Abstract

A series of poly(vinyl alcohol) (PVA), PVA/chitosan (CS) and PVA/cyanobacterial exopolysaccharide (EPS) blend nanofibrous membranes were fabricated by electrospinning using a microfiltration poly(vinylidene fluoride) (PVDF) as a basal membrane, in order to obtain thin-layer composite (TFC) nanofiltration membranes. The morphology, diameter, structure, mechanical and thermal characteristics of electrospun nanofibers were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), dynamical and mechanical analysis (DMA), thermogravimetry (TGA) and differential scanning calorimetry (DSC). The morphology and diameter of the nanofibers were mainly affected by concentration of the blend solution and weight ratio of the blend, respectively. Thermal and mechanical analysis demonstrated that there were strong intermolecular hydrogen bonds between the molecules of CS-PVA and EPS-PVA in the blends. The heat-treated electrospun blended membranes showed better tensile mechanical properties when compared with PVA alone, and resisted more against disintegration. Nanofiltration was successfully performed in a high pressure cell.