Characterization of commercial nanofiltration membranes and comparison with self-made polyethersulfone membranes

Characterization of commercial nanofiltration (NF) membranes is necessary to explain and control membrane fouling. Therefore, six different polymeric NF membranes (UTC20, N30F, Desal51HL, Desal5DL, NTR7450 and NFPES10) were characterized. The molecular weight cut-off was determined from PEG measurements, whereas streaming potential measurements enabled quantification of the surface charge characteristics. The roughness of the membranes was measured by atomic force microscopy (AFM) in the non-contact and tapping modes. Hydrophobicity was studied by tapping mode AFM (including phase imaging) and by contact angle measurements. The results indicated that the polyethersulfone membranes (N30F, NTR7450 and NFPES10) have the largest MWCO and the smoothest and most hydrophobic membrane surface. A comparison between the characteristics of commercial and selfmade polyethersulfone membranes confirms that they are similar.