Structure influence of hyperbranched polyester on structure and properties of synthesized nanofiltration membranes

Nanofiltration (NF) membranes have been prepared by interfacial polymerization of hyperbranched polyester with different number of terminated hydroxyl groups and trimesol chloride (TMC). Surface morphology and chemical structure of the different membranes were characterized by Fourier transforms infrared spectrometry (FTIR-ATR), scanning electron microscopy (SEM), atom force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Molecular weight cut-off (MWCO) and surface zeta potential of the NF membranes were evaluated. The effect of pH value, operation pressure and salt concentration on rejection properties were also assessed. Nanofiltration properties were determined with organic anionic and cationic simulated dye wastewater. It was found that all NF membranes surface presented negative charge and had a MWCO of 4–6 kDa. Rejection properties of the NF membranes were affected by the dye charges, dye concentration and salt concentration.