Novel positively charged PVDF/SPES membranes surface grafted by hyperbranched polyethyleneimine (HBPEI): Fabrication, characterization, antifouling properties, and performance on the removal of cationic E-coat paint

Surface modification of ultrafiltration membranes has shown a significant potential to reduce fouling and increase flux and lifetime, which are the most important factors in membrane filtration. In this study, the surface-modified membranes were prepared by grafting hyperbranched polyethyleneimine (HBPEI) onto polyvinylidene fluoride (PVDF)-sulfonated polyethersulphone (SPES) blending membranes. Electrostatic interactions between HBPEI and SPES result in a well-attached positive-charged HBPEI grafting layer on the PVDF membrane surface. Surface-modified membranes were examined for the removal of cationic E-coat paint and their performance was measured in terms of total permeation flux, paint rejection, and fouling resistance parameters. In addition, the physicochemical properties and morphology of the membranes were examined by field emission scanning electron microscopy (FESEM), Fourier-transformed infrared spectroscopy (FTIR), atomic force microscopy (AFM), and water contact angle (CA). The optimum membrane shows a total permeation flux of 35.5 L per square meter per hour (LMH) and paint rejection of 99.9%. Additionally, the fouling parameter of the optimized membrane shows a flux recovery ratio of 90%. As a result of its considerable properties, such as the high flux and separation performance as well as its antifouling properties, the surface modified membrane is an excellent candidate for the removal of E-coat paint at industrial scale.