Preparation and characterization of antibacterial polyamine-based cyclophosphazene nanofiltration membranes

A novel positive-charged polyamine-based cyclophosphazene nanofiltration membrane (NF) was prepared via interfacial polymerization between branched polyethyleneimine (PEI) and hexachlorocyclotriphosphazene (HCCP). The composite membranes were characterized using ATR-FTIR, XPS, SEM, AFM, water contact angle, and zeta potential analysis. The membrane with optimal performance was prepared by interfacial reaction with 5 wt% PEI (M-n = 600 g/mol) in aqueous phase, 1 wt% HCCP in organic phase, 5 min dwell time, and 15 min curing time at 100 degrees C. The resultant membrane has a 97% rejection to MgCl2 and a water permeation of 55 L/m(2) h when testing at 1.5 MPa and 25 degrees C with a 1000 ppm salt solution. The results for filtrating various dyes showed that the PEI/HCCP membrane could remove small organic compounds and contaminants. Antibacterial assay results indicated that the membrane had a nearly 100% bacterial inhibitate rate against both Gram-negative E. coli and Gram-positive S. aureus. In addition, all bacteria in a concentrated suspension (10(7) CFU/mL) could be completely eliminated within 20 min contacting with the PEI/HCCP membrane. Finally, a 140 h cross-flow testing indicates an excellent membrane performance stability.