Preparation of fouling resistant PSF flat sheet UF membrane using amphiphilic polyurethane macromolecules

• Amphiphilic PU macromolecules were synthesized and used in PSF membrane.
• Higher pore density and hydrophilicity were achieved.
• Enhanced hydration capacity and lower BSA adsorption were found.
• The flux recovery ratio was higher than 91% for the PU modified membrane.

In this work four different types of amphiphilic PU macromolecules were synthesized with end capping of citric acid, malic acid, lactic acid and 4-hydroxy benzoic acid. The chemical structure of the macromolecules was confirmed by NMR and FTIR spectroscopy. PSF was directly blended with these additives and membranes were fabricated by phase separation method. Morphology and surface chemical features were analyzed with SEM, FESEM, AFM, FTIR–ATR and water contact angle. Blended membranes showed enhanced pore density, pure water flux, hydration capacity and hydrophilicity compared to plain membrane. SEM photographs showed significant change in cross sectional morphology of modified membrane with highest wt.% of additive. Hydration capacity, PWF, BSA adsorption and WCA for the modified membrane with 6 wt.% of PU-CA were 225 mg/cm3, 138.2 L/m2 h, 0.019 mg/cm3 and 49.5° compared to 130 mg/cm3, 102.4 L/m2 h, 0.14 mg/cm3 and 63.5° respectively, for the plain membrane. The anti-fouling behavior of membranes was also studied with BSA ultra-filtration. The flux recovery ratio for all the modified membranes was higher than the plain membranes with the highest value of more than 91%.