Poly(ether sulfone)-based ultrafiltration membranes using chitosan/ammonium chloride to enhance permeability and antifouling properties

The presence of microorganisms on filtration membranes can cause biofouling phenomena. In this study, poly(ether sulfone)- (PES)-based functional ultrafiltration membranes were developed by employing chitosan (CS) and ammonium chloride (NH4Cl) as antibacterial agents to enhance antibiofouling properties. A PES membrane was prepared using the phase inversion method and then immersed in CS/NH4Cl solutions containing different NH4Cl concentrations to form composite membranes. The membrane antibiofouling properties were evaluated using Kirby Bauer and total plate counting methods. The structures and properties of the composite membranes were characterized by FTIR spectroscopy, SEM-EDX, porosity and hydrophilicity measurements, and tensile tests. The addition of NH4Cl increased the antibiofouling properties of the membranes, where maximum bacteria-killing ratio (%BKR) values of 99.2 and 83.3% were observed against Staphylococcus aureus and Escherichia coli, respectively. The addition of CS/NH4Cl not only modified the morphological structure of the PES membrane but also increased its hydrophilicity (water contact angle from 82.3 to 64.4°), porosity (49.6 to 70%), and mechanical strength (0.57 to 8.7 MPa). The results from performance tests, compared with other similar membrane systems, firmly suggest that the synthesized membranes are promising for water and wastewater purification through the ultrafiltration method.