Preparation and Characterization of Hydrophilic Composite Nanofiltration Membrane by Interfacial Polymerization

Abstract

Hydrophilic nanofiltration membranes have drawn increasing attention owing to their high flux and anti-fouling characteristics. To improve the hydrophilicity of a polysulfone nanofiltration membrane, inorganic salt sodium phosphate in aqueous phase is added during interfacial polymerization (IP). In this study, hydrophilic composite nanofiltration membranes were prepared through IP and were then characterized in terms of their morphology and performance using scanning electron microscope (SEM), atomic force microscope (AFM), water contact angle, determination of pure water flux, and magnesium ion removal. The improved performance of the membranes was verified in terms of pure water permeability and rejection of inorganic salts. Results showed that the optimal monomer concentrations for different monomers are 1.5% of sodium phosphate, 1.0% of PIP, and 0.25% of 1,3,5-benzenetricarbonyl trichloride. The optimum reaction time of the aqueous and organic phases can be controlled for 1 min, and the optimum thermal treatment is 70 °C for 12 min. The SEM, AFM, and hydrophilic testing results indicated that the ultrafiltration substrate membrane surface has a compact and ultrathin functional layer, and the addition of sodium phosphate can improve the hydrophilicity of the resultant membrane. Therefore, inorganic salts, such as sodium phosphate, may be considered a potential additive for enhancing the performance of composite nanofiltration membranes.