Surface modification of ultrafiltration membranes by preadsorption of a negatively charged polymer: I. Permeation of water soluble polymers and inorganic salt solutions and fouling resistance properties

Polyethersulfone ultrafiltration membranes (MWCO: 9000, 35,000 and 85,000) were surface modified by preadsorption of poly(sodium 4-styrenesulfonate) (PSS) upon the permeation of aqueous solution of the polymer for about 100 min. Membranes with lower MWCO values were modified primarily on the top surface, whereas high MWCO membranes were modified both on the surface and pore walls as well. The IR spectra of surface modified membranes show absorption bands at 1040 cm −1 due to symmetric vibration of SO 3 − group, and at 2925 and 2852 cm −1 corresponding to asymmetric and symmetric stretchings, respectively, of aliphatic (backbone CH 2 and CH) unit present in PSS. Surface modified membranes have shown separations of 28–56% for Na 2SO 4, 11–19% for NaCl and